By Bidyashree Tripathy

SOIL ATTRIBUTES AS INFLUENCED BY MAIZE BASED CONSERVATION AGRICULTURE PRODUCTION SYSTEM

(CAPS) IN A Fluventic Haplustepts UNDER NORTH CENTRAL PLATEAU ZONE OF ODISHA

A

THESIS SUBMITTED TO THE ORISSA UNIVERSITY OF AGRICULTURE AND TECHNOLOGY

BHUBANESWAR

IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF

MASTER OF SCIENCE IN AGRICULTURE (SOIL SCIENCE AND AGRICULTURAL CHEMISTRY)

By

Bidyashree Tripathy

DEPARTMENT OF SOIL SCIENCE AND AGRICULTURAL CHEMISTRY COLLEGE OF AGRICULTURE

ORISSA UNIVERSITY OF AGRICULTURE AND TECHNOLOGY BHUBANESWAR-751003

2014

THESIS ADVISOR: DR. K. N. MISHRA

ORISSA UNIVERSITY OF AGRICULTURE AND TECHNOLOGY

DEPARTMENT OF SOIL SCIENCE AND AGRICULTURAL CHEMISTRY

COLLEGE OF AGRICULTURE, BHUBANESWAR

Dr. K. N. Mishra Associate Professor, Soil Science Bhubaneswar AICRP on IFS & Co-PI SMARTS Date: 31.07.14 Directorate of Research Bhubaneswar, Odisha

CERTIFICATE-I

This is to certify that the thesis entitled “Soil attributes as

influenced by Maize based Conservation Agriculture Production

System (CAPS) in a Fluventic Haplustepts under North Central

Plateau zone of Odisha” submitted in partial fulfilment of the

requirements for the award of the degree of Master of Sciences in

Agriculture (Soil Science and Agricultural Chemistry) to the

Orissa University of Agriculture and Technology is an authentic

record of bona fide research work carried out by Bidyashree

Tripathy under my guidance and supervision. No part of this thesis

has been submitted for any other degree or diploma.

It is further certified that the evidence and help obtained

by him from various sources during the course of investigation has

been duly acknowledged.

(K. N. Mishra) CHAIRMAN

ADVISORY COMMITTEE

CERTIFICATE CERTIFICATE CERTIFICATE CERTIFICATE –––– IIIIIIII

This is to certify that the thesis entitled “Soil attributes as

influenced by Maize based Conservation Agriculture Production

System (CAPS) in a Fluventic Haplustepts under North Central

Plateau zone of Odisha” Submitted by Bidyashree Tripathy to

Orissa University of Agriculture and Technology, Bhubaneswar in

partial fulfilment of the requirements for the degree of Master of

Science in Agriculture (Soil Science and Agricultural Chemistry)

has been approved/disapproved by the students’ Advisory Committee

and the external examiner.

Advisory Committee

CHAIRMAN: Dr. K. N. Mishra Associate Professor Soil Science

AICRP on IFS & Co-PI SMARTS

Directorate of Research MEMBERS: Dr. A. K. Pal

Professor and Head Dept. of Soil Science and Agricultural Chemistry

Dr. L. M. Garnayak Chief Agronomist AICRP on IFS OUAT, Bhubaneswar

EXTERNAL EXAMINER:

ACKNOWLEDGEMENT

One of the joys of completion is to look over the journey and remember all the persons

who have helped and supported along the ebbs and tides of this long but fulfilling road. It is my

pleasure and privilege to appreciate the persons whose constant efforts, motivation and well

wishes paved a path for me to write this column. In this moment, I am short of words to express

my feelings of gratitude and reverence and am just pouring a drop from the ocean of

indebtedness in form of words.

I ascribe all glory to the gracious, omnipotent and omnipresent Almighty, for his silent

blessing and kindness which acted as a savoir in the time of disasters and guarded me all along.

I am extremely delighted and feel blessed to have worked under the guidance of

excellent pursuing and ever helpful personality, Honourable chairman of my Advisory

committee, Dr. K. N. Mishra, Associate Professor, Soil Science and Agricultural Chemistry,

AICRP on IFS and CO-PI SMARTS, OUAT, Bhubaneswar. His invaluable and timeless

suggestion, constant inspiration, affectionate dealings, constructive criticism and advice helped

me at every stage. His innovative ideas, meticulous nature and close monitoring of the research

work molded the manuscript with perfection. My sense of obligation is negligible and

unquantifiable in respect of his energy and time spent on this endeavor. His benevolent

personality made a great impression on me and I wish to inculcate his positive energy.

I take privilege of expressing gratitude and gratefulness to Dr. L. M. Garnayak, Chief

Agronomist, AICRP on IFS for his concern and magnanimity in providing the research

laboratory and timely co-operation in all my statistical formalities. His help and advice is

always invaluable and it is my golden opportunity to have him as the member of my Advisory

committee.

It is my pleasure to express my deepest sense of regards to Dr. A. K. Pal, Professor and

Head, Department of Soil Science and Agricultural Chemistry, OUAT for his kind words,

immense patronage and encouragement in the study period.

I acknowledge with sincerity the fellowship awarded to me by the OUAT-University of

Hawaii collaborative research project “Sustainable Management of Agro-ecological Resources

for Tribal Societies (SMARTS)” for my research and study. In this context, I fell elated to

express my deepest sense of regards and infinitum gratitude to the members of SMARTS

Project Scientific team comprising of Dr. P.K. Roul, Associate Director of Research; Dr. K.N.

Mishra, Sr. Scientist (Soil Science); Dr. S.N. Dash, Associate Professor (Fruit Science) from

OUAT and Dr. C. Chan Halbrendt, Professor (NREM); Dr. T.W. Idol, Associate Professor

(NREM); Dr. C. Ray, formerly Interim Director, Water Resource Research Centre, from

University of Hawaii, USA for their immense patronage and valuable suggestions during the

course of my investigation.

I owe my heartiest gratefulness to the esteemed teachers of Department of Soil

Science And Agricultural Chemistry, Dr.S.Nanda, Dr.K.C.Pradhan, Dr.B.Dash,

Dr.S.K.Pattnayak, Dr.G.H.Santra, Dr.P.K.Das,Dr.A.Mishra, Dr.K.K.Rout, Dr.S. Mohanty,

Dr.A. K. Das, Dr.R.K.Nayak, Miss B.Jena, Dr.M.Mandal, Mr.S.Soren,Mr.M.Behera for

their timely suggestion and guidance throughout my post-graduate studies.

I am profoundly indebted to Dr. D. Jena, (former HOD of Soil Science) for his

encouragement, support and discussion during the course of formulation of the research topic.

My heartiest and sincere reverence to Dr. B. Hota (former Assoc. Professor, Dept. of Plant

Physiology) for being the anchor and guide since I stepped into this institution.

I am very much thankful to the help and cooperation of non-teaching staffs of the

department Bun bhai, Bulubhai, Anil bhai who acted as Lilliputians in handling the huge

research work. Thank you Dilip Sir, Sameer Sir, Majhi Sir, Mohanty Sir, Madhu didi,

SMARTS PC Shivashis bhai for their words of care and concern.

I express my deep love to my lovely friends Nita, Hyn, Prativa, Jessy Dee, Sipra,

Sushree, Gayatri who soothed and comforted me in my frustrations and despair. I thank all my

friends, sincere juniors and batchmates Meera, Trupti, Rahul, Shiva, Shyam bhai, Snehasish for

their kind cooperation. My heartiest gratitude is to my senior Ayesha Dee for her facile

suggestion and motivation.

I solicit the benediction of my parents, Nana and Bou for my progress and prosperity.

My Bou’s constant prayers and pious advices kept all negativity and failures in bay. I respect

the abundant love and shower of blessings of all my family members. I thank my beloved

brother, Milu for his unfathomable love and impulsiveness.

Any omission in acknowledgement does not mean lack of gratitude. Lastly, to all of

you, Thank You..!

Bhubaneswar

Dated (Bidyashree Tripathy)

ABSTRACT

Soil degradation due to loss of forest cover, water erosion and shifting cultivation

coupled with continuous monocropping of maize in intense tillage have led to a quest for

sustainable production practices with greater resource use efficiency in the rain-fed agro

ecosystem under North Central Plateau zone of Odisha. In order to reverse this harmful trend,

conservation agriculture production system (CAPS) with the components of minimum tillage,

legume based intercrops and follow up cover crop has been established in a Fluventic

Haplustepts at Regional Research and Technology Transfer Station, OUAT at Kendujhar

district of Odisha during 2011 in split plot design and the impact of CAPS on BD, WSA, SOC,

soil moisture and microbial attributes across the profile (0-5, 5-10 and 10-20 cm) was assessed

at the end of the 3rd cropping cycle. The treatment combinations are Conventional tillage (CT)

and Minimum tillage (MT) with sole Maize (M) and inter crop Maize + Cowpea (M+C) in

main-plots during wet season and Horsegram (H), Toria (T) and no cover crop (NCC) in sub-

plots during dry season. Surface accumulation and retention of SOM under MT decreased the

BD (-3.4%, -2.6%), increased the dry season moisture contents and SOC (+27.9%, +15.2%) in

the top two layers. Higher SOC in MT increase the water stable micro-aggregates (+14.9%,

+11.9%) with concomitant decrease in micro-aggregates(-14.8%, -14.5%) in 0-5 and 5-10 in

layers, indicating the low turn-over of macro-aggregates. Depletion of SOM induced by soil

conversion under CT systems increased the BD (+1.5%, +2.2%), decreased the SOC (9.8%, -

15.7%), macro-aggregates (-5.3%, -5.7%). The higher population of bacteria (+31.0%, +

25.5%), fungi (+22.0%, +18.6%) and actinomycetes (+ 19.9%, + 14.8%) and MBC (+88.1%,

+49.9%) in the top layers in MT over CT is due to higher build up and protection of SOM. The

pronounced effect of cover crops due to litter inputs was reflected on SOC (+13.0%), Macro-

aggregates (+7.2%), population of bacteria (+21.8%), fungi (+15.1%), actinomycetes (+12.2%)

and MBC (+21.5%) in the surface layer of 0-5 cm. The attributes in the bottom layers (10-20

cm) remain unaffected by tillage practices because of low and lack of variation in SOC

contents. The study singles out SOC as the most dominant soil parameter affecting soil BD (r =

- 0.85** , r = -0.89** ), water stable macro-aggregates (r = 0.90** , r = 0.76** ), soil moisture ( r =

0.82** , r = 0.82** ), MBC ( r = 0.98** , r = 0.99** ), population of bacteria ( r = 0.91** , r = 0.77** ),

fungi ( r = 0.86** , r = 0.88** ) and actinomycetes ( r = 0.87** , r = 0.86** ) in the surface (0-5 cm)

and sub surface (5-10 cm) layers. Though the MEY of MT and CT systems are at par, the

established positive trend in restoration and enrichment of soil attributes at the end of the 3rd

year will enhance the productivity of soil on long term basis.

CONTENTS

CHAPTER PARTICULARS PAGE

I INTRODUCTION 1

II REVIEW OF LITERATURE 4

III MATERIALS AND METHODS 25

IV RESULTS 39

V DISCUSSION 69

VI SUMMARY AND CONCLUSION 80

BIBLIOGRAPHY i-xiv

LIST OF TABLES

3.1 Mean Monthly meteorological data during the cropping season 28

(2013 - 2014)

3.2 Treatment details 31

3.3 Crop varieties and their duration 33

3.4 Fertiliser dose for different experimental crops grown 33

4.1 Soil BD (Mg m-3) as influeneced by different CAPS 40

4.2a Effect of CAPS on water stable macro-aggregates (>0.25mm) 43

4.2b Effect of CAPS on water stable micro-aggregates (0.053-0.25mm) 45

4.3a Effect of CAPS on soil moisture content (%) at 0-5cm depth 47

4.3b Effect of CAPS on soil moisture content (%) at 5-10cm depth 48

4.3c Effect of CAPS on soil moisture content (%) at 10-20cm depth 49

4.4 Effect of CAPS on soil pH (1:2.5) 51

4.5 Soil Organic Carbon (g kg-1) as influenced by CAPS 53

4.6 Bacterial population (×106 cfu g-1) as influenced by CAPS 56

4.7 Population of fungi (×104 cfu g-1) as influenced by CAPS 58

4.8 Population of actinomycetes (×106 cfu g-1) as influenced by CAPS 60

4.9 Impact of CAPS on soil MBC (µg C g-1) 62

4.10 Microbial quotient (MBC/ SOC) [%] as influenced by CAPS 65

4.11 Effect of CAPS on Maize Equivalent Yield (q ha-1) 66

TABLE PARTICULARS PAGE

LIST OF FIGURES Figure Particulars Page

3.1 Agroclimatic zones of Odisha 26

3.2 Study area with profile site and external land features 27

3.3 Mean monthly rainfall and rainy days during the cropping 29 season (April 2013-March 2014)

3.4 Mean monthly temperature and relative humidity data during 29 the cropping season (April 2013-March 2014)

3.5 Layout plan of the experiment plot 30

3.6 Representative pedon of the experimental site 32

3.7 Many coarse and medium lime nodules and carbonate coats 32 in ‘B’ horizon

3.8 Site features around the pedon site 32

3.9 Wet-sieving of Water stable aggregates 35

3.10 Chloroform (CH3Cl) fumigation for MBC 35

3.11 Actinomycetes population in both CT and MT type of 35 cropping systems

3.12 Maize stalk and residue incorporation in MT system 35

4.1 Soil BD (Mg m-3) as influenced by CAPS. Treatmnets with 41 same lower case letter within main plots or sub-plots were not significant at P = 0.5

4.2a Effect of CAPS on water stable macro-aggregates (>0.25mm) 44 Treatments with same lower case letter within main plots or sub-plots were not significant at P = 0.05

4.2b Effect of CAPS on water stable micro-aggregates (0.053-0.25mm) 46 Treatments with same lower case letter within main plots or sub-plots were not significant at P = 0.05

4.3 Periodical soil moisture content across the profile 50

4.4 pH of soils of 0-5cm depth as influenced by CAPS. Treatments 52 with same lower case letter within main plots or sub-plots were not significant at P = 0.05

4.5 Soil Organic Carbon (g kg-1) as influenced by CAPS. Treatments 54 with same lower case letter within main plots or sub-plots were not significant at P = 0.05

4.6 Bacterial population (×106cfu g-1) as influenced by different CAPS. 57 Treatments with same lower case letter within main plots or sub-plots were not significant at P = 0.05

4.7 Fungal population (×104cfu g-1) as influenced by different 59 CAPS. Treatments with same lower case letter within main plots or sub-plots were not significant at P = 0.05

4.8 Population of actionomycetes (×106cfu g-1) as influenced 61 by different CAPS

4.9 Microbial Biomass Carbon (µg of C g-1) as affected by CAPS. 64 Treatments with same lower case letter within main plots or sub-plots were not significant at P = 0.05

4.10 Microbial quotient across the profile as influenced by CAPS. 65 Treatments with same lower case letter within main plots or sub-plots were not significant at P = 0.05

4.11 Effect of different CAPS on Maize Equivalent Yield (q ha-1) 66 Treatments with same lower case letter within main plots or sub-plots were not significant at P = 0.05

4.12a Depth wise graph showing distribution of SOC, WSA 67 under different tillage systems

4.12b Depth wise graph showing distribution of MBC and Microbial 68 quotient under different tillage systems

5.1 Correlation of SOC with BD 70

5.2 Correlation of SOC with water stable macro-aggregates 71

5.3 Correlation of SOC with water stable micro-aggregates 72

5.4 Correlation of SOC with soil moisture content at sowing and 73 flowering at 0-5cm soil depth

5.5 Correlation of SOC with pH in 0-5cm soil layer 74

5.6 Correlation of SOC with MBC of the soils 76

5.7 Correlation of SOC with bacterial population of the soils 77

5.8 Correlation of SOC with fungal population of the soils 78

5.9 Correlation of SOC with actinomycetes population of soils 78

ABBREVIATION

FAO : Food and Agriculture Organisation CAPS : Conservation Agriculture Production System CA : Conservation Agriculture CT : Conventional Tillage MT : Minimum Tillage SOC : Soil Organic Carbon HG : Horsegram NCC : No Cover Crop BD : Bulk Density NT : No Tillage WSA : Water Stable Aggregate MBC : Microbial Biomass Carbon Mg : Megagram µg : microgram ha : Hectare CD : Critical Difference SE(m) : Standard Error mean SMC : Soil Moisture Content NS : Non-significant

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1

INTRODUCTION

Food security for our country’s burgeoning population is becoming

increasingly difficult and this challenge needs to be met in the face of the changing

consumption patterns, impacts of the climate change and degradation of the finite land

and water resources. Management of land resources, in general, encompass, crop

production methods that will keep pace with country’s food needs, sustaining

environment, blunting impacts of climate change, preserving and enhancing natural

resources, and supporting livelihood of farmers and rural population of the country.

Sustainable crop production without any degradation of natural resources can be

achieved through a set of crop-nutrient-water-landscape system management practice

popularly known as conservation agriculture production system.

Conservation agriculture (CA) involves minimal soil disturbance, continuous

retention of residues on the soil surface and a diverse and rational use of crop

rotations (Erenstein et al., 2008). Conservation agriculture production systems

(CAPS) are tailor-fit system approaches for successful adoption and implementation

of CA to specific locations (Agustin et al., 2012).

Soil organic matter (SOM) is an important determinant of soil fertility,

productivity and sustainability and is a useful indicator of soil quality in tropical

agricultural systems where nutrient pool and highly weathered soils are managed with

little external input (Lal, 1997). In the humid and sub-humid tropics, climate is

especially aggressive and soils are frequently deficient in nutrients and prone to

erosion, while the rate of SOM decomposition is usually high. The role of SOM in

moderating the major soil quality indicators like SOC, BD, aggregation, moisture, and


2

microbial biomass carbon is well documented. The dynamics of SOM are influenced by

agricultural management practices such as tillage, crop residues and cropping systems as

the basic components of CAPS. Conventional tillage practices and removal of crop residues

can lead to a reduction of SOM due to accelerated decomposition and loss of organic matter

in rich top soils (Arshad et al., 1990), thereby adversely affecting soil properties.

In response to above challenges, scientists have focused on developing alternative

cropping system over the past few decades and conservation agriculture production

systems are among those that have been the most extensively tackled. They rely on

three principles:

i. A significant reduction in soil tillage

ii. A permanent soil protection through cover crops

iii. Increased bio-diversity through diversification of crop rotation and/or

intercropping

Minimum tillage are those systems which are ploughless but do not

completely abandon tillage and such reduced tillage systems vary largely in terms of

machinery used and of tillage depth. The tillage systems reaching a maximum depth

of 10 cm are defined as minimum tillage (MT). Several studies world over indicate

that MT soils increases SOM, MBC, aggregation and microbial densities. Crop

rotation can affect SOM because the SOM content depends on the type of crop

rotation, the quality and quantity of crop residues and since crop residues are

precursors of the SOM pool, returning more crop residues to the soil is associated

with an increase in SOC concentration (Fuentes et al., 2012). Cover crops or crop

residues should be maintained on the soil surface as dead or live mulch and the

objective is to protect the soil against weather aggressions and water erosion, to

maintain soil moisture, to suppress weed growth and to provide shelter and food for


3

the soil biota. Therefore, conservation agriculture production systems (CAPS) appear

to be interesting options to achieve sustainable and intensive crop production under

different agro-ecological environments because they use available resources

efficiently and maintain soil fertility.

Despite the considerable research done world over, which show the benefits of

CAPS on SOC, very little effort has been done in the rainfed agro-ecosystem under

North Central Plateau zone of Odisha to investigate the influence of CAPS on soil

attributes. Keeping these facts in view, a field experiment with maize based CAPS has

been established at Regional Research and Technology Transfer Station, Kendujhar

during 2011 and objectives of the present study are described below.

Objectives

The objective of the study is to assess the influence of maize based CAPS

involving tillage practices (minimum tillage and conventional tillage), cropping

systems (maize sole and maize+cowpea intercrop) and both with and without cover

crops (horsegram and toria) on soil attributes across the profile at the end of 3rd

cropping cycle (2013-14). The studies are:

1. Determination of soil BD and water stable macro and micro

aggregates

2. Determination of gravimetric moisture content (during rabi season

cover crops)

3. Monitoring the pH, and organic carbon status of the soils

4. Monitoring the microbial attributes viz. population of bacteria, fungi,

actinomycetes and microbial biomass carbon (MBC) of the soils

5. Assessing the impact on Maize Equivalent Yield (MEY)

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4

REVIEW OF LITERATURE

Conservation agriculture production system (CAPS) is a tool box of practices

for successful adoption and implementation of conservation agriculture (CA) to

specific locations. Some of the significant research findings on CA, relevant to the

present study “ Soil attributes as influenced by maize based conservation

agriculture production system (CAPS) in a Fluventic Haplustepts under North

Central Plateau Zone of Odisha” have been thoroughly reviewed and presented in

this chapter under the following heads.

2.1 Conservation Agriculture Production System (CAPS),

Definition, Principles and Importance.

2.2 Impacts of Conservation Agriculture Production System

(CAPS) on soil health

2.2.1 Soil physical properties

2.2.1.1 Bulk density

2.2.1.2 Water stable aggregates

2.2.1.3 Soil Moisture Content

2.2.2 Soil chemical properties

2.2.2.1 Soil reaction (pH)

2.2.2.2 Organic carbon

2.2.3 Soil microbial properties (population of bacteria, fungi

actinomycetes and microbial biomass carbon)

2.3 Conservation Agriculture Production System (CAPS ) -Yield


5

2.1 Conservation Agriculture Production System (CAPS), Definition, Principles and Importance.

2.1.1 Definition of conservation agriculture

Conservation agriculture (CA) can be defined as “ a concept for

resource-saving agricultural crop production that strives to achieve acceptable

profits together with high and sustained production levels while concurrently

conserving the environment” (FAO,2007).

‘ Conservation Agriculture’ refers to a general set of practices that are focused on

three main concepts - minimum tillage to reduce soil disturbance; continuous soil

cover to reduce rainfall impact, suppress weeds and conserve organic matters and

optimal crop rotation to maintain soil fertility and provide nutritional self-efficiency

(FAO, 2010).

Conservation tillage is a widely-used terminology to denote soil

management systems that result in at least 30% of the soil surface being

covered with crop residues after seeding of the subsequent crop to reduce soil

erosion. (Jarecki and Lal, 2003; Uri, 1999).

Conservation agriculture (CA) can be defined as “ a concept for resource-saving

agricultural crop production that strives to achieve acceptable profits together with

high and sustained production levels while concurrently conserving the environment”

(FAO,2007).

‘Conservation Agriculture’ refers to a general set of practices that are focused on

three main concepts - minimum tillage to reduce soil disturbance; continuous soil cover

to reduce rain fall impact, suppress weeds and conserve organic matters and optimal crop

rotation to maintain soil fertility and provide nutritional self-efficiency (FAO,2010).


6

2.1.2 Principles of conservation agriculture

Conservation agriculture makes use of soil biological activity and cropping

systems to reduce the excessive disturbance of the soil and to maintain the

crop residues on the soil surface in order to minimize damage to the environment

and provide organic matter and nutrient.

Conservation agriculture production system is characterized by three

principles which are linked to each other (FAO, 2010), namely:

1. Continuous minimum mechanical soil disturbance, mainly through

direct seeding = No-tillage

2. Permanent organic soil cover, organic matter supply through the

preservation of crop residues and cover crops = Mulching and

Cover cropping

3. Diversification of crop species grown in sequence or associations

for biocontrol and efficient use of the soil = Rotation

Reduced tillage or no-tillage is also a principal component of CA as it is

designed to improve soil quality. This differs from conventional tillage by

advocating minimum soil disturbance and promoting direct seeding which involves

growing crops without mechanical seedbed preparations after harvesting the

previous crop (Calegari, 2008).

Cover crops are grown to provide soil cover and are killed before seeding. They

have been used to augment biomass of crop residues, protect soils against erosion and

promote build up of soil organic matter (Muza et al., 2007). They are an integral

component of CA and the main focus of this study.


7

Generally planned rotations involving cereals and legumes are

necessary to promote nutrient recycling because of distinct rooting depths in cereal-

legume systems (Tsubo et al., 2003).

2.1.3 Importance of conservation agriculture

Conservation agriculture advocates the combined social and

economic benefits gained from combining production and protecting the

environment, hence it becomes in integration of ecology management with

modern scientific agricultural production. This is compounded by the fact that

yield improvement under farming takes a few years to be manifested

(Hubbs et al., 2007).

Conservation agriculture production system are recommended as a general

solution to the problems of rural communities facing poor agricultural

productivity and declining natural resource quality (Derpsch, 2003; Hubbs,

2007; Hubbs et al., 2008).

Compared to conventional tillage there are several benefits from conservation

tillage such as economic benefits by labour, cost and time saved, erosion

protection, soil water conservation and increases of soil organic matter (Uri et

al.1998; Wang and Gao, 2000)

2.2 Impacts of Conservation Agriculture Production System (CAPS) on soil health

Doran and Parkin (1994), Doran and Safley (1997) initially

distinguished between “ soil quality” and “ soil health” before inclusively using

the term “ soil health” and defining it as “ the continued capacity of soil to

function as a vital living system, within ecosystem and land-use boundaries, to


8

sustain biological productivity, promote the quality of air and water environments,

and maintain plant, animal and human health”.

However, the general perception of a healthy or high-quality soil is one that

adequately performs functions, which are important to humans, such as providing a

medium for plant growth and biological activity, regulating and partitioning

water flow and storage in the environment and serving as an environmental buffer in

the formation and destruction of environmentally hazardous compounds.

Reeves (1997) noted that “ SOC is the most often reported attribute from long-

term agricultural studies and is chosen as the most important indicator of soil

quality and agronomic sustainability because of its impact on other physical,

chemical and biological indicators of soil quality” .

For example, the humic fraction is considered the principal pool in contributing

to the soilís CEC, whereas soil structure is provided and maintained by both the

humic and particulate organic carbon (POC) fractions. Here, the POC fraction plays a

greater role in sandy soils as a means of physically binding particles together. In

turn, this means that with an increase in SOC content, there is increased aggregation

and decreased Db, which tend to increase the total pore space as well as the number

of small pore sizes (Haynes and Naidu,1998).

Over a long period, improved organic matter under the practice of

Conservation Agriculture promoted good soil structure and macro-porosity. Water

infiltrates easily, similar to forest soils (Machado, 1976).

Tillage and residue management increased soil profile water content.

(Nicou and Chopart, 1979, Unger, 1991 and Bruce et al., 1995) reported that

soil nutrients become stratified when no-till management is employed.


9

Cover crop residues remaining on the surface can reduce evaporation, thus

conserve soil moisture, lower soil surface temperatures, provide a certain degree of

weed control, and minimize erosion (Liebl et al., 1992).

Reducing tillage affects several aspects of the soil. With time, conservation

tillage improves soil quality indices (Dick, 1983; Lal et al., 1998), including

soil organic C storage (Dick, 1983; Lamb et al., 1985; Unger, 1991; Bruce et

al.,1995; Potter et al., 1998).

Conservation tillage is an effective practice to control soil degradation on

intensively farmed cropland (Larney and Kladivko, 1989; Grant and Lafond,1993)

and to increase soil water storage (Dao, 1993).

The advantages of conservation tillage practices over crop residues to act as

an insulator and reducing soil temperature fluctuation; (N. D. Uri,1999) building up

soil organic matter; conserving soil moisture (Schwab and Reeves, 2002; West and

Post, 2002).

No-tillage is a sustainable cropping management system that protects soil,

water, air, and biodiversity (Hubbs et al., 2007; Campbell et al., 2006;

Calegari et al., 2008).

Soils managed using reduced tillage generally have more surface plant

residues, higher moisture content, and better structure and aggregation

compared to soils managed under Conventional tillage. (Reeves 1997)

Crop residues left on the soil surface lead to improved soil aggregation and

porosity, and an increase in the number of macro-pores, and thus to greater


10

infiltration rates. On bare soil, runoff and thus soil erosion is greater than when the

soil is protected with residue cover (Ruedell, 1994).

No tillage retained the highest moisture followed by minimum tillage, raised bed and

conventional tillage in inceptisols under semiarid regions of India (Sharma et al., 2011).

Karlen et al. (1994) showed that normal rates of residue combined with

zero-tillage resulted in better soil surface aggregation, and that this could be

increased by adding more residues.

Surface (0-30 cm) soil in a no-till system was shown to contain more moisture

and to be cooler than a comparable plough tillage soil (Doran et al.,1998).

Residue retention and direct seeding have a major influence on improving

water infiltration, organic matter content and fertility of a soil (Wall,1999).

No-tillage practices featuring residue cover and less soil disturbance have

been shown to reduce runoff by 52.5% and reduce erosion by 80.2% compared

to traditional tillage (Wang, 2000). Landers (2001) concluded an improvement of

the infiltration capacity under NT farming.

Trials conducted in the higher potential areas of Zimbabwe between 1988

and 1995 indicated that mulching significantly reduced surface runoff and hence

soil loss (Erenstein, 2002).

Luo et al. (2005) reported that conservation tillage can improve soil physical

properties and soil fertility in northern China and Bescanca et al. (2006) reported

that Conservation tillage leads to positive changes in the physical, chemical

properties of a soil. Conservation agriculture improves soil quality such as improved


11

sequestration of organic carbon and improved soil fertility reported by (Hobbs and

Gupta, 2004).

Bolliger (2006) observed that positive changes on soil physical and chemical

properties occur only after several years of practicing conservation agriculture. NT

has positive effects on soil properties, yields and prevents erosion (Derpsch, 2006).

2.2.1 Soil physical properties


Bulk density is related to natural soil characteristics such as texture,

organic matter, soil structure (Chen et al., 1998).

A study on long term impact of no-till on soil properties and crop productivity

on Canadian prairies by Lafond et al. (2011) revealed that the lower soil BDs for the

native soil is likely due to more aggregation and higher litter content at the soil

surface. The higher soil BD on the convex areas of LTNT and STNT would have

also been strongly influenced by a combination of tillage and water erosion moving

soil into the concave areas, thus explaining the lower soil BD for concave areas.

While reviewing some of the studies on the effect of no- tillage on soil BD,

Fengyun et al. (2011) observed that the lower soil bulk density when compared with the

traditional methods by the end of the growing season may be derived from the more

intense plant root operation, soil organism movement and the function of soil freeze and

melt, as well as the well known increased soil water content and increased crop residue

amounts, would also decrease bulk density in the 0 to 5 cm soil layer.

Experiments on different tillage practices in sloppy terrains of North- West

Tuinisia by Jemai et al. (2013) showed significant reduction of BD and enhancement


12

of TP (Total Porosity) under NT 7, that may be attributed to the considerable

improvement in SOM and biotic activity by residue incorporation.

The study on the effect of conservation tillage practices on soil water holding

capacity in the Loess plateau, China has indicated that conservation tillage practices

can increase the water and nutrient contents of the soil, reduce soil erosion, improve

soil structure and increase crop yields. NTS (NT with corn straw) treatments

decreased the soil bulk density and increased the soil porosity in 2008 and 2009

relative to the PT (Plough Tillage without corn straw) treatment (Liu et al., 2013)

The studies of Latif et al. (1992) revealed that legume intercrops in a

conservation agriculture system significantly decreased the soil bulk density and

penetration resistance.

Ekeberge and Riley (1997) found that bulk density was lower with minimum tillage

than with conventional tillage at a depth of 3-7cm in a loam soil in Southeast Norway.

Kay and Vanden Bygaart (2002) observed that bulk density was lower under

minimum tillage than mouldboard plough in the top 20cm of the soil profile

with the greatest difference at 5-10cm. This was probably due to organic matter

content at 0-5cm was greater under minimum tillage than mouldboard plough.

D’Haene et al. (2008) reported that bulk density was lower in 5-10cm soil

layer under minimum tillage than conventional tillage on silt loam soils with

crop rotations in Belgium.

Hernanz et al. (2002) found significantly lower bulk density under minimum

tillage than conventional tillage from 0-10cm with cereal mono-culture and


13

from 0-15 cm in a wheat-vetch (Vicia sativa l.) rotation. But the more

compacted top soil with minimum tillage had no adverse effect on crop yield

with either rotation.

Blanco-Canqui et al. (2006) reported that maize residue retention at 5 and

10 Mg/ha for a period of one year reduced bulk density in 0-5cm layer from

1.42 Mg/m3 ( control) to 1.26 Mg/m3 and 1.22 Mg/m3 respectively in minimum

tillage system in a silt loam soil.

Thomas et al. (2007) reported that bulk density was lower with minimum

tillage than with conventional tillage in the top 10cm of a Luvisol in Southern

Queensland.

2.2.1.2 Water stable aggregate

Several researchers related increased macro-aggregate contents to

higher inputs of fresh organic material due to increased microbial activity and the

production of microbial and fungal derived binding agents (Mikha and

Rice, 2004).

This increase in the concentration of SOC is considered to be the result of

different interacting factors, such as less mixing and soil disturbance, increased residue

return, reduced surface soil temperature, higher moisture content and decreased

risk of erosion (Logan et al., 1991; Blevins and Frye, 1993).

Six et al. (2000b) and Jacobs et al. (2009) found for long-term agricultural

field experiments a decrease of macro-aggregate contents under CT in

comparison with no-tillage (NT) and reduced tillage (rotary harrow to 5-8 cm

depth), respectively.


14

In contrast, conventional tillage (CT) disrupts macro-aggregates and formerly

incorporated Corg is exposed to microbial decomposition (Balesdent et al.,

2000; Six et al., 2000a; Tan et al., 2007; Zotarelli et al., 2007)

Greater aggregate stability was anticipated because the conservation

management practices were expected to increase the amount of labile C

available for use by microbial communities, which in turn, would produce more

organic binding agents and sticky fungal hyphae as a means to stabilize soil

Conceptual model of the ‘life cycle’ of a macro-aggregate (Six et al., 2000a)

Macro-aggregates (Roberson et al. 1991 ; Angers et al. 1992). Macro-

aggregation, in turn, may increase the proportion of labile organic C that is

physically protected from microbial decomposition (Boehm and Anderson 1997).


15

The classical theory of aggregate formation and turnover has been postulated

by Six et al., 2000a. Following incorporation of fresh residues, soil micro-organisms

utilize the more easily available C and produce mucilages (solution gum) resulting

the formation of macro-aggregates around coarse (>250 µm) Intra-aggregate

Particulate Organic Matter (coarse iPOM). Coarse iPOM is further decomposed and

fragmented into fine iPOM. The fine iPOM and associated mucilages bind the

minerals, form the organic core of a newly developed micro-aggregates within

macro-aggregate. The latter process is cut short if the macro-aggregate turnover is

increased by disturbance resulting in a reduced sequestration of C.

It has been established that the inclusion of organic materials within soil

aggregates reduces their decomposition rate. Increases in aggregation concomitant

with increases in organic C have been observed in NT systems. Tillage has been

found to induce a loss of C-rich macro-aggregates and a gain of C-depleted micro-

aggregates However, this decrease in macro-aggregates cannot explain the total C

loss associated with tillage. The increased macro-aggregate turnover under CT is a

primary mechanism causing decreases of soil C. Macro-aggregate formation and

degradation (i.e. aggregate turnover) is reduced under NT compared to CT and leads

to a formation of stable micro-aggregates in which carbon is stabilized and

sequestered in the long term( Six et al., 2000).

The fractionation of water-stable aggregates and density fractionation may

thus be helpful for an improved understanding of C dynamics affected by soil

management, since aggregate and density fractions are more sensitive to changes

in soil management than total Corg Water-stable macro-aggregates were enriched

in younger organic material and have faster turnover times than micro-aggregates

(Andruschkewitsch et al., 2013).


16

Aggregate stability in the surface soil of a sloping land is an important

predictor of run-off, sediment and carbon loss through water erosion. It mainly

depends on SOC which is influenced by land use practices. The contribution of

coarse soil aggregate (>0.05 mm) in adsorption of SOC is more than micro

aggregates (<0.05 mm), while it is damaged by improper agriculture activities

(such as heavy tillage practices, burning of crop residue), grazing and forest

clearance. Furthermore, the coarse soil aggregate is reduced mainly by long- term

conventional tillage practices (Heshmati et al., 2011).

The study of Li and Pang (2010) on a silty clay loam soil in China revealed that

long-term (33 years) practices of this tillage resulted in reduction of 22% in coarse

aggregates and increase of 34% in fine aggregates (Li, G.L. and X.M. Pang, 2010).

When no tillage was continuously practiced for 4 years, 11 years and 20 years

in Typic Xerofluvents of north east Spain, it was observed that small macro- aggregates

(0.250-2.0mm) & micro-aggregates(0.053-0.250mm) increased at a depth of 0-5cm

and 5-10cm. In contrast, small macro-aggregates and micro- aggregates reduced in

conventional tillage (D. Plaza Bonilla et al, 2013).

Conventional tillage (CT) disrupts macro-aggregates (Gale et al., 2000). Micro-

aggregates are more stable than macro-aggregates and tillage subsequently disrupts large

aggregates more than smaller aggregates (Cambardella and Elliot, 1993).

In red tropical latosols in Brazil, it was found that no-tillage system had the

best aggregation indices for the 0-20 cm layer due to the increase in the organic

carbon content. , Castro Filho et al. (2002).


17

In Florida, a no tillage chronosequence study of 0, 6, 10 and 15 years in

commercial plots revealed that there exist a relationship between the increase

in the surface soil water stable macro aggregate and the hydrolysable organic carbon

with longer years under no tillage (Ochoa et al., 2009).

2.2.1.3 Soil moisture contents

In a seven-year study (Jones, 2000), it was found that zero tillage systems with

cereal residue retention could enhance the soil moisture status.

Minimum tillage treatments produced higher maize yields than conventional tillage

treatments and conserved more soil moisture in the soil. The results also indicated that

minimum tillage treatments had more compact and moister soil surface than conventional

tilled treatments. Overall increased crop yield under minimum tilled treatments was

associated with improved soil moisture conservation (Gicheru et al., 2005).

Minimum tillage with vegetative barriers not only reduced soil loss though erosion,

also conserved soil moisture in the dry season that was reflected in improved yield

(Guto et al., 2012).

Tillage reduction in association with residue retention significantly increased the

water holding capacity in the present study, mainly due to large increase in soil

organic C in residue retained treatments in dryland agro-ecosystem at BHU, Varnasi

(Kushwaha et al., 2001).

Daraghmeh et al., 2009 observed that tillage reduction in association with residue

retention significantly increased the moisture contents in the surface layers mainly due to

large increase in SOC in a typical Danish morainic sandy loam Agrudalfs.


18

2.2.2 Soil chemical properties

2.2.2.1 Soil reaction (pH)

Soils under NT practice are frequently more acidic in the surface layers but less acidic

in deeper layers than under CT practice as a result of an increase in organic matter and

associated organic acids and changes in the proportions of cations and anions in soil under

NT practice (Logan et al., 1991; Prasad and Power, 1991; Kern and Johnson, 1993).

Increase in soil organic C and N and a slight pH decline in the seed zone

under conservation agriculture practices improves the soil quality (Bessam

and Mrabet, 2003).

There was a significant negative correlation between pH and organic carbon

concentration ( r = -0.88, P ˂0.01), indicating that greater organic carbon under NT

may at least partially have had an acidifying effect. (Thomas et al., 2007 ).

2.2.2.2 Organic carbon and organic matter

On a Vertisols in southern Queensland, highest concentration of organic C in

the surface soil was found with a combination of NT, stubble retention and fertilizer

N (Dalal, 1989) or NT and stubble retention (Thompson, 1992).

Heenan et al. (1995) also found greater amount of organic C in 0ñ10 cm

depth under NT and stubble retained than under CT and stubble burned in a

coarse- textured red earth with 29% clay.

The studies of Six et al., (2000a) and Tan et al., (2007) revealed that the lower

physical impact of conservation tillage increases aggregate stability, leading to lower

aggregate turnover rates and therefore improved physical protection of Corg from

decomposition and thus higher Corg stocks in arable soils. In contrast, conventional


19

tillage (CT) disrupts macro-aggregates and formerly incorporated Corg is exposed to

microbial decomposition

When no tillage was practiced for 7 years continuously in the sloppy

terrains of North-West Tuinisia, the soil organic matter was found to be more i.e.

31.0 g kg-1 & 24.1 g kg-1 at depths of 0-10 cm & 10-20 cm. But soil organic matter

was much lower i.e. 20.6 g kg-1 & 22.4 g kg-1 at depths of 0-10 cm and 10-20

cm respectively when conventional tillage was practiced (Jemai et al., 2013).

Long term studies on no tillage in a Typic Xerofluvents of North east Spain

indicated that the increase in the proportion of stable macro-aggregates and the

enrichment of C concentration of micro-aggregates are the main mechanisms of

SOC protection when NT is maintained over time (D. Plaza- Bonilla et al., 2013).

Studies conducted under a wide range of climatic conditions, soil types, and

crop rotation systems showed that soils under no-tillage and reduced tillage

have significantly higher soil organic matter contents compared with conventionally

tilled soils (R. Alvarez, 2005).

Havlin et al. (1990) determined that reducing tillage and maintaining surface

residues in a long-term study increased soil organic carbon content. He conducted an

experiment having three crop rotation-continuous soybean, continuous sorghum,

sorghum-soybean. These were managed for 12 years under conventional and no

tillage systems (0 and 100% surface residue cover respectively). Under no tillage soil

organic matter increased up to 45% as the level of residue increased from 1 to 3 t/ha/yr.

A study in eastern Paraguay about “changes in soil organic matter after

land use change” showed that no tillage practices had a significant higher


20

organic matter content compared with conventional tillage practices (Riezebos

and Loerts, 1998).

In Texas, Zibilske et al. (2002) recorded that no tillage resulted in soil

organic matter increase up to 58% in the top 4cm of soil for no till treatment.

Six et al. (2002) concluded that there is an increase in soil organic matter

after doing a literature review about soil organic matter dynamics in tropical

and temperate countries under the NT system. He concluded that in the upper 40

cm the soil organic matter increases after 6-8 years.

Balota et al. (2004) showed that in Brazil in a 20-year experiment

residue retention and minimum tillage increased organic carbon by 45% at 0-

50cm depth compared with traditional tillage.

Madari et al. (2005) and Riley at al. (2005) showed that conservation tillage

with residue cover had higher total organic carbon in soil aggregates than

traditional tillage in Brazil. He reported that addition of crop residues in

combination with minimum tillage can yield attainable carbon

accumulation rates up to 0.36 Mg C ha-1 yr-1.

Li et al. (2006) conducted a 4 years no-tillage experiment and showed that

active C and total organic C down to 10 cm depth were up to 5% higher in no-

tillage than traditional tillage systems.

Liang et al. (2007) demonstrated that no tillage significantly increased the

concentration of soil organic C in 5-20 cm soil layer by 5.6-5.9% on the clay

loam soils after 3 years in the humid north eastern China.


21

Field experiment conducted in Santo Antonio de Goias, Brazil by A.S.

Nascente et al. (2013) revealed that the use of cover crops such as millet and the no-

tillage system increased C and N concentrations in each of the light fractions of the SOM.

Although total SOM was little changed during the two years of this experiment, the

various C fractions were significantly affected by the tillage. They concluded that SOM

physical fractionation is good indicator to show significant differences caused by the soil

management in the organic matter dynamics in a short period of time.

2.2.3 Soil microbial properties (population of bacteria, actinomycetes and microbial biomass carbon)

Roldan et al. (2003) showed that after 5 years of NT maize in Mexico, soil

wet aggregate stability had increased over conventional tillage (TT) as had soil

enzymes, soil organic carbon (SOC) and microbial biomass (MB). They

conclude that NT is a sustainable technology.

CA results in more biotic diversity in the soil as a result of the mulch and

less disturbance. The surface mulch also helps moderate soil temperatures and

moisture, which is more favorable for microbial activity. MBC is 83% higher in

MT that CT (Balota et al., 2004).

Studies on Impact of tillage and residue incorporation on soil microbial

biomass C and N in dry land farm (Inceptisols) of BHU by Kushwaha et al.

(2001) indicated that when flushes of C are supplied to the soil in the form of

crop residues, the microbial biomass increases in size until the substrate is

depleted. In the present study, residue retention and tillage reduction both

increased the level of soil microbial biomass, the maximum effect on microbial

biomass being recorded in MTCR, either alone or in combination.


22

It has been reported that use of minimum and zero tillage retained more crop

residue C as soil organic C and soil MBC compared to conventional tillage

(Salinas-Gracia et al., 1997). Singh and Singh (1993) stated that microbial

growth due to the application of organic matter such as straw is mainly

dependent on the availability of C in the soil; they reported 77% increases for

MBC and MBN under straw C fertilizer, and 51 and 84% increases under

straw treatment for MBC and MBN, respectively.

Soil organic matter (SOM) also plays a key role in soil quality The size of

the microbial community is directly proportional to SOM content and soil

microbes are the principal mediators of nutrient cycling (Hamel at al.,

2006). Although soil microbial biomass represents only a small proportion of

overall SOM, it is more dynamic than total SOM and a better indicator of how

tillage and cropping systems impact soil health and productive capacity (Lupwayi

et al., 1998, 1999; Campbell et al., 2001).

Although fungal dominance is commonly assumed in no-till soils, the relative

abundance of fungi over bacteria is not consistently greater in the Northern

Great Plain soils under long-term no-till practices compared with intensive

tillage (Helgason et al., 2009).

Using NT and/or cover crop systems can alter enzymatic activity

(Bandick and Dick 1999; Dick 1994), microbial biomass (Linn and Doran

1984; Wagner et al., 1995; Kirchner et al., 2003; Zablotowicz et al., 1998a),

microbial community structure (Lupwayi et al., 1998; Feng et al., 2003), and

macroflora diversity (Gaston et al., 2003; Reeleder et al., 2006).


23

Results of many researchers indicated the importance of reducing tillage as a

means of increasing soil biological activity of the topsoil. (Zibilske & Bradford,

2003; Mijangos, et al., 2006; M̧ ler et al., 2009). Authors have shown that

even a reduction in tillage leads to increased microbial activity and biomass in

contrast to surface soil under conventional tillage (Von Lu zow et al., 2002).

Alternation to no tillage or increased cropping intensity increases microbial

biomass C (MBC) in response to increase nutrient reserves and improved soil

structure and water retention (Biederbeck et al., 2005).

The microbial diversity, measured by the Shannon diversity index (SDI),

was significantly higher in samples from no-tillage system plots in four

taxonomic levels (order, family, genus and species), which agree with Ceja-

Navaro et al. (2010), who found that soils under no-tillage had the highest levels of

microbial diversity compared to the conventional tillage system.

2.2 Conservation agriculture production system (CAPS) - Yield

In the Douglas-Daly and Katherine districts of the Northern Territory,

dryland crops of maize, sorghum, soybean and mungbean sown using no- tillage

with adequate vegetative mulch on the soil surface have produced yields

comparable with, or higher than (especially in drier years), those obtained

under conventional tillage (Thiagalingamb et al., 1996).

Tarkalsona et al. (2006) reported that application of NT system in a long term

period led to indicative improvement in wheat productivity in comparison with CT

system.


24

Shams-Abadi and Rafiee (2007) resulted that using MT, leads to increase

wheat production. Higher yields obtained in conservation agriculture through better

water use and improved soil quality. (Mrabet, 2000).

At Pinnarendi in a similar environment under semi-commercial conditions,

but where surface mulch was apparently not sufficient to reduce soil temperature and

weeds were poorly controlled, yields of peanut, maize and sorghum were lower

under no-tillage than under reduced tillage (Cogle et al., 1995)

Lal (1991) reported from two studies of 8 years or more that larger

maize grain yields were maintained with a mulch based no tillage system than

with a plough based system.

`tàxÜ|tÄá tÇw `xà{Éwá

25

MATERIALS AND METHODS

Conservation agriculture practices with the three components of reduced

tillage, residue retention and crop rotation have potential benefits on soil health that

has been well documented. However, the results vary due to soil type, cropping

system, residue management and climate. A long term field experiment has been

initiated during 2011 at the Regional Research and Technology Transfer Station

(RRTTS) of OUAT, Kendujhar located under the rainfed agro-ecosystem of the North

Central Plateau zone of Odisha (Fig.3.1) and the programme is a joint collaboration of

Orissa University of Agriculture and Technology and University of Hawaii, USA

named ‘SMARTS’ (Sustainable Management of Agricultural Resources for Tribal

Societies). The impact of Conservation Agriculture Production System (CAPS) at the

end of 3rd cropping cycle was assessed in this study with the following materials and

methods.

3.1. MATERIALS

3.1.1 Description of the study area

The experimental site is located in ‘B’ block of RRTTS Kendujhar (Fig. 3.2)

(85˚ 34’ 30.61” E, 20˚ 50’ 55.38”N, 499m above MSL) and the tract is under Agro

Ecological Sub-region (AESR) 12.3 and North Central Plateau Agro-climatic zone of

Odisha. The soils of the experimental sites developed from colluvial-alluvial deposits

in piedmont plain with sandy clay loam to sandy loam texture and belong to Fluventic

Haplustepts as per soil taxonomy.


26

Fig. 3.1. Agroclimatic zones of Odisha

RRTTS, Keonjhar

North Central

Plateau Zone

`tàxÜ|tÄá tÇ

w `xà{Éwá

26


27

STUDY AREA WITH PROFILE SITE AND EXTERNAL LAND FEATURES

Fig. 3.2. Study area with profile site and external land features

`tàxÜ|tÄá tÇ

w `xà{Éwá

27


28

3.1.2. Climate and weather parameter

The climate of the study area is hot, moist, sub-humid with average annual

rainfall of 1527.3mm and more than 75% of the rainfall is received in the months

from May to September. The mean maximum and minimum temperatures are 31.3˚C

and 19.5˚C, respectively and the afternoon relative humidity varies from 34.7% in

March to 87.5% in September.

The weather parameters during growing season of the study year are presented

in Table 3.1 and Fig. 3.3 and 3.4.

Table 3.1 Mean monthly meteorological data during the cropping season (2013 –2014)

Month Mean

Monthly Rainfall (mm)

Rainy Days

Mean monthly Temperature (0C)

Mean Monthly Relative Humidity (%)

Max. Min. FN AN

2013 April 52.7 5 36.66 20.06 65.3 29.1 May 35.0 3 39.16 23.96 83.8 29.8 June 312.7 16 32.20 21.93 82.8 48.5 July 277.9 18 30.71 22.41 87.1 57.9 August 253.0 13 30.16 22.83 87.3 58.6 September 196.6 14 30.80 21.90 87.8 59.5 October 296.0 14 28.03 19.29 91.9 70.6 November 1.1 0 27.93 13.53 79.5 43.5 December 0 0 26.29 9.41 77.7 38.0 2014 January 0 0 26.70 10.00 76.5 34.2 February 46.3 3 29.25 11.93 65.2 26.8 March 26.7 2 31.96 16.38 62.2 23.7

3.1.3 Experimental design and Treatment details

The design of the experiment is split-plot with three replications. The treatment

details are conventional (CT) and minimum (MT) tillage with maize


29

Fig. 3.3 Mean monthly rainfall and rainy days during the cropping season (April 2013 – March 2014)

Fig. 3.4 Mean monthly temperature and relative humidity data during the cropping season (April 2013 – March 2014)

0

2

4

6

8

10

12

14

16

18

20

0

50

100

150

200

250

300

350

April May June July Aug. Sept. Oct. Nov. Dec. Jan. Feb. March

No

. o

f D

ay

s

Ra

infa

ll (

mm

)

Month

Rainfall (mm) Rainy days

0

10

20

30

40

50

60

70

80

90

100

5

15

25

35

45

55

65

75

April May June July Aug. Sept. Oct. Nov. Dec. Jan. Feb. March

Re

lati

ve

Hu

mid

ity

(%

)

Tem

pe

ratu

re (◦C

)

Month

Min. Temp. Max. Temp. AN R.H. FN

`tàxÜ|tÄátÇw`xà{Éwá

30

RI RII RIII

CT-M-NCC

MT-M+C-T

MT-M-H

MT-M+C-H

CT-M-T

CT-M+C-NCC

CT-M-H MT-M+C-NCC MT-M-NCC MT-M+C-T CT-M-H CT-M+C-T

CT-M-T MT-M+C-H MT-M-T MT-M+C-NCC CT-M-NCC CT-M+C-H

MT-M-NCC CT-M+C-H CT-M-T CT-M+C-NCC MT-M-T MT-M+C-H

MT-M-H CT-M+C-NCC CT-M-H CT-M+C-T MT-M-H MT-M+C-NCC

MT-M-T CT-M+C-T CT-M-NCC CT-M+C-H MT-M-NCC MT-M+C-T

Fig. 3.3 Layout plan of the experiment

Main plot (Kharif) Sub plot (Rabi)

Experimental Design: Split plot CT-M - Conventional til lage with sole maize NCC-No cover crop Number of treatments: 12 CT-M+C - Conventional tillage with maize +cowpea T-Toria Number of replication: 03 MT-M - Minimum tillage with sole maize H-Horse gram Individual plot size: 7.2m43.2m MT-M+C - Minimum tillage with maize + cowpea

`tàxÜ|tÄá tÇ

w `xà{Éwá

30

N


31

sole (M) and maize cowpea intercrop (M+C) in main plots during wet season

(Kharif) and no cover crop (NCC), horse gram (HG) and toria mustard (T) in sub-

plots during dry season (Rabi), resulting a total of twelve different combinations.

The treatment details and layout design are depicted in Table3.2 and Figure3.5

respectively.

Table 3.2. Treatment details

Treatment Descriptions

Main plot ( Kharif season)

CT-M Conventional tillage with sole maize

CT-M+C Conventional tillage with maize + cowpea

MT-M Minimum tillage with sole maize

MT-M+C Minimum tillage with maize + cowpea

Sub-plot (Rabi season)

NCC No cover crop

HG Horsegram as cover crop

TORIA Toria as cover crop

3.1.4 Field preparation

The conventional tillage (CT) involves three mould board ploughing without

residue to a depth of 20-25 cm and in minimum tillage (MT), one shallow disking is done

up to a depth of 10 cm with addition of chopped main crop (maize, cowpea) and cover crop

(horsegram, toria) biomass as surface residues.

3.1.5 Crop management

The crop varieties used in the experiment, their duration, date of sowing as

well as harvesting is given below.


32

Fig. 3.6 Representative Pedon of the experimental site

Order- Inceptisol

Sub-oder- Ustepts

Great group- Haplustepts

Sub-group- Fluventic Haplustepts

Fig.3.8. Site features around the pedon site

Fig.3.7. Many coarse and medium lime nodules


33

Table 3.3 Crop varieties and their duration

Crops Variety Duration

Maize Pioneer 30R-77 90-100days

Cowpea Utkalmanika 75days

Horsegram Athagarh local

100days

Toria (Mustard) Anuradha 75-80days

3.1.6 Fertilizer management

The recommended chemical fertilizers applied to Maize, Cowpea, Toria and

Horsegram were indicated in the Table 3.4. The fertilizer applied for Maize +

Cowpea was based on additive series, taking into consideration 100 per cent

plant population of maize and 50 percent plant population of cowpea. The fertilizers

were applied i n l i n e basally for the crops except maize where nitrogen was applied

in three split viz. 25% basal, 50% at first earthing up and rest 25% at second

earthing up stage.

Table3.4 Fertilizer dose for different experimental crops grown

Crops

Fertilizer Dose (kg ha-1)

N P2O5 K2O

Maize 80 40 40

Cowpea 20 40 20

Mustard 40 20 20

Horsegram 20 40 20

3.1.7 Sowing, Seedrate and Spacing

During kharif season, for sole maize, spacing of 60cmx30cm was adopted

for which a seed rate of 15kg ha-1 was required. But, maize + cowpea as intercrops

were sown in 1:1 ratio at a uniform spacing of 30cm. The spacing adopted for


34

cowpea was 15cm from plant to plant within the row. A seed rate of 10 kg ha-1 was

required taking into consideration that the cowpea plant population was 50% of

normal sole cowpea. In Minimum tillage practice, Maize and Cowpea seeds

were sown by dibbling in line. In Conventional tillage practice, line sowing of

seeds was done and the seeds were covered with soil after sowing. A seed rate of

7.5kg and 25 kg ha-1was required for toria and horsegram, respectively.

3.2 METHODS

3.2.1 Collection and processing of soil samples

Soil samples were collected after harvest of the cover crops in the month of

February, 2014.

Soil samples from each plot consisted of composite samples that were

collected with a narrow spade and divided into segments of 0-5, 5-10 and 10-20cm,

placed in plastic bags and brought to the laboratory immediately for analysis. Field

moist samples were gently passed through a 10mm sieve and dried at 40˚C for 48

hours and 100g of dry soil samples were used for determining water stable aggregates.

A portion of fresh soil samples were sieved through a 2mm sieve and stored at 4˚C for

analysis of various microbiological tests. Another portion of the sieved soils were air

dried (2-3 days) and used for determination of organic carbon and pH. Undisturbed

core samples from each layers were collected with a core sampler (5.0cm diameter)

for determination of soil bulk density. Soil cores from each depth were also collected

during sowing, flowering and harvesting of dry season cover crops for determination

of gravimetric moisture content.


35

Fig.3.9. Wet-sieving of Water stable aggregates Fig.3.10. CH3Cl Fumigation for MBC

Fig. 3.11. Actinomycetes population in both CT and MT type of cropping systems

Fig.3.12. Maize stalk and residue incorporation in MT system


36

3.2.2 Methods of Soil Analysis

a) Physical analysis


The bulk density of the soils from the experimental plots was analysed by core

method (Blake, 1965).

3.2.2.2 Water stable aggregates (WSA)

The WSA in the soils were determined using 250µm and 53µm mesh sieve

by wet sieving method (Kemper and Rosenau,1986). A sample of 100g air-dried (8-

mm sieved) soil was placed on the top of a 2-mm sieve and submerged for 5 min in

deionized water at room temperature to allow slaking (Kemper and Rosenau, 1986).

Sieving was manually done (when the sample was submerged) by moving the sieves up

and down 3 cm, 50 times in 2 min to achieve aggregate separation. A series of two sieves

(0.25 and 0.053 mm) was used to obtain the two aggregate fractions: (1) 0.25–2-mm

(macro-aggregates), (2) 0.053–0.25-mm (micro-aggregates). Soil aggregate fractions

retained on different sieves, were oven dried (500C), weight expressed in percentages.

3.2.2.3 Soil Moisture Content (SMC)

The SMC in the soils were determined by gravimetric method. The soil

samples are collected and dried in the hot air oven at 105˚C for 24 hours. Moisture

content is determines by measuring moist weight and dry weight of the soil. It is

expressed as percentage of moisture content per weight of dry soil (Dastane, 1972).

b) Chemical analysis

3.2.2.4 Soil pH

As suggested by Jackson (1973) the pH of soil samples of the

experimental plots was determined in 1:2.5 soil:water suspension after equilibration


37

for half an hour with intermittent stirring using the glass electrode digital pH meter,

‘SYSTRONICS’ (modelM.K.VI).

3.2.2.5 Organic carbon

The organic carbon of soils of representative pedon and experiment was

determined by modified Walkley and Black’s rapid titration method (Jackson,

1973) using Ferroin indicator (Chopra and Kanwar, 1986).

c) Microbial analysis

3.2.2.6 Enumeration of soil microbial population

Soil microbial population was determined by serial dilution and spread plate

technique. One gram of the soil sample was added to test tube containing 9 ml of distilled

water, serially diluted (Dhingra and Sinclair, 1993) spread over Nutrient Agar,

Actinomycetes Isolation Agar and Potato Dextrose Agar for enumeration of bacteria,

actinomycetes and fungi, respectively. The plates were incubated at 30˚C for 24 hours

for bacterial isolation and at 30˚C for 48 hours for actinomycetes and fungal isolation.

Calculation

The following mathematical deduction was followed for enumeration of the

microbial colony and expressed as CFU per gram of soil.

CFU/ml = No. of colony Inverse of dilution taken

Volume of inoculum taken

×

3.2.2.7 Soil microbial biomass carbon

Microbial biomass carbon was estimated employing fumigation and

extraction procedure as described by Vance et al.,(1987). The process

involved collection of filtrate using Whatman filter paper no.2 by shaking

unfumigated soil (20 g) with 0.5 M K2SO4 for 30 minutes. Similarly another set


38

of filtrate was collected using fumigated soil exposed to ethanol free

chloroform for 24 hours. Organic carbon in both the extract was analyzed using

the method of digestion titration. For digestion of organic carbon 10 ml of

filtrate was transferred into a conical flask and 10 ml of K2Cr2O7 followed

by 20 ml of conc. H2SO4 were added and the entire content was digested for

30 minutes at 1700C .After the content in the flask cooled down, 25 ml

distilled water and 5 ml, ortho-phosphoric acid were added to the digested

material and titrated against 0.04 M Ferrous ammonium sulphate with

Ferroin as the indicator.

Calculation

Microbial biomass carbon = EC fumigated soil - EC of unfumigated soil

Kc

where, EC = Extractractable carbon

Kc = 0.379 (Kc is the K2SO4 extract efficiency factor (Hu and Cao, 2007)

3.2.2.8 Maize-equivalent yield

Maize equivalent yield (MEY) was calculated by the formula as follows :

MEY (q/ha) = Yield of other crop produce (q/ha) price of that produce(Rs/q)

Price of maize grain (Rs/q)

×

The maize equivalent yield of the cropping system was obtained by addition

of yield of maize component and the maize equivalent yield of other component

crop taken in intercropping and the Rabi crop if any (toria and horsegram).

3.2.2.9 Statistical analysis

Data in respect of soil physical and chemical properties for various

treatments were subjected to analysis of variance following standard statistical

procedure (Gomez and Gomez, 1984).

exáâÄàá

39

RESULTS

The impact of Conservation Agricultural Production System (CAPS)

involving tillage methods and cropping systems (intercrop, cover crop) on soil health

has been assessed after three cropping years in the present study. Results pertaining to

some of the major soil physical, chemical and biological parameters influenced by

adoption of CAPS, have been described in this section.

4 SOIL PARAMETERS OF THE EXPERIMENT

4.1 SOIL PHYSICAL PARAMETERS

4.1.1 Bulk Density (BD)

Soil Bulk Density is one of the most common variables used to assess soil

physical properties. Conventional and minimum tillage with cropping systems like sole

or intercrop of maize and follow-up cover crops affected the soil BD (Table 4.1,

Fig.4.1)significantly across the soil profile at the end of third cropping cycle. Practice of

minimum tillage (MT) reduced the soil BD in the tune of 3.4% and 2.6% over the initial

values (1.32 and 1.37 Mg m-3) in 0-5 and 5-10 cm depths, respectively, whereas, these

soils under conventional tillage (CT) registered higher BD (+1.5%, + 2.2%).Cover

cropping (HG, TORIA) also lowered the soil BD by 1.3% and 1.0% in the depth ranges

of 0-5 cm and 5-10 cm, respectively over the soil under NCC (1.32 and 1.38 Mg m-3).

For 10-20 cm range, no significant variation in soil BD was observed among different

treatments.

exáâÄàá

40

Table 4.1 Soil BD (Mg m-3) as influenced by CAPS

0-5 cm layer

Particulars NCC HG TORIA Mean

CT-M 1.38 1.35 1.36 1.36 CT-M+C 1.34 1.32 1.31 1.32 MT-M 1.29 1.28 1.29 1.28 MT-M+C 1.28 1.26 1.28 1.27 Mean 1.32 1.30 1.31 Initial 1.32

M S M within S S within M SEm(±) 0.010 0.003 0.012 0.007

CD (0.05) 0.04 0.01 NS NS

5-10cm layer



M S M within S S within M

SEm(±) 0.007 0.003 0.009 0.007

CD (0.05) 0.02 0.01 NS NS

10-20cm layer




SEm(±) 0.009 0.004 0.011 0.009

CD (0.05) NS NS NS NS

exáâÄàá

41

Fig. 4.1 Soil BD (Mg m-3) as influenced by CAPS. Treatments with same lower case letter within main plots or sub-plots were not significant at P = 0.05

1.22

1.24

1.26

1.28

1.3

1.32

1.34

1.36

1.38

INITIAL CT-M CT-M+C MT-M MT-M+C NCC HG TORIA

1.32

a

b

cc

a

cb

BD

(M

g m

-3)

Treatments

0-5 cm

1.28

1.3

1.32

1.34

1.36

1.38

1.4

1.42


1.37

a

b

c

c

a

b b

BD

(M

g m

-3)

Treatments

5-10 cm

1.43

1.44

1.45

1.46


1.44

NS

NSNS

NS

NS

NS NS

BD

(M

g m

-3)

Treatemnts

10-20 cm

exáâÄàá

42

4.1.2 Water Stable Aggregates

Aggregate measurement is very often used as surrogates of the complex soil

matrix for studies of soil organic matter dynamics.

4.1.2.1 Macro-aggregates (>0.25mm)

The organic binding by-products resulting from accumulation of organic matter

in the surface layers (0-5 cm) significantly increased the water stable macro-aggregated

in different MT treatments. The data pertaining to macro-aggregates in different layers

are depicted in Table 4.2a. and Fig.4.2a. Practices of MT resulted in significant increase

in proportion of macro-aggregates in 0-5 cm and 5-10 cm layers and the gain was in the

tune of 14.9% and 11.9%, respectively, over the initial values (58.2%, 52.88%). Soils

under CT in these two top layers exhibited a reduction of macro-aggregates by 5.3% and

5.7%. The soils in the layer of 10-20 cm did not show any variation in macro-aggregates

among different treatments. Treatments with cover crops elevated the status of macro-

aggregates in the tune of 7.2% and 4.9% in the two top layers over NCC at the end of

the 3rd cropping year.

4.1.2.2 Micro-aggregates (0.053 – 0.25 mm)

Tillage reduction and residue retention decreases the proportion of micro-

aggregates in the soil because of slower turnover of macro-aggregates. The proportion of

micro-aggregates under MT treatments was distinctly reduced by 14.8% and 14.5% in 0-

5 cm and 5-10 cm layers (Table 4.2b. and Fig.4.2b.) over the initial value of 17.7% and

19.2%, respectively. The concomitant increase of micro-aggregates in the soils under CT

treatments was 5.9% and 4.3% for the top two layers. The bottom layers (10-20 cm) of

both MT and CT exhibited no noticeable variation in the proportion of micro-aggregates

(Table 4.2b). Treatments with cover crops could not influence the status of micro-

aggregates much.

exáâÄàá

43

Table 4.2a. Effect of CAPS on water stable macro-aggregates (>0.25mm) (%)

0-5cm layer

Particulars NCC HG TORIA Mean CT-M 52.88 56.67 53.99 54.51 CT-M+C 52.80 57.39 56.92 55.70 MT-M 62.16 67.29 65.37 64.94 MT-M+C 64.86 72.03 69.93 68.94 Mean 58.17 63.34 61.55 Initial 58.22 M S M within S S within M SEm(±) 1.269 1.087 2.182 2.174 CD (0.05) 4.39 3.17 NS NS

5-10cm layer

Particulars NCC HG TORIA Mean CT-M 46.08 50.24 49.94 48.75 CT-M+C 48.06 52.63 51.76 50.82 MT-M 57.47 59.07 58.96 58.50 MT-M+C 58.39 61.13 59.77 59.76 Mean 52.50 55.76 55.11 Initial 52.82


CD (0.05) 5.32 NS NS NS

10-20cm layer Particulars NCC HG TORIA Mean

CT-M 39.86 43.70 42.87 42.15 CT-M+C 42.86 44.38 43.67 43.64 MT-M 44.36 47.52 46.56 46.15 MT-M+C 44.42 47.31 46.39 46.04 Mean 42.88 45.73 44.87 Initial 44.72 M S M within S S within M SEm(±) 0.900 1.244 2.221 2.487


exáâÄàá

44

Fig. 4.2a. Effect of CAPS on water stable macro-aggreagtes (>0.25 mm) Treatments with same lower case letter within main plots or sub-plots were not significant at P = 0.05.

58.2b b

aa

b

a a

0

10

20

30

40

50

60

70

80


WS

A (

> .

25

0 m

m)

[%]

Treatments

0-5 cm

52.8b b

a a

NSNS NS

0

10

20

30

40

50

60

70


WS

A (

> .

25

0 m

m)

[%]

Treatments

5-10 cm

44.72

NS

NS

NS NS

NS

NS

NS

40

41

42

43

44

45

46

47


WS

A (

> .

25

0 m

m)

[%]

Treatments

10-20 cm

exáâÄàá

45

Table 4.2b. Effect of CAPS on water stable micro-aggregates (0.053-0.25 mm)(%)

0-5cm layer




CD (0.05) 1.75 NS NS NS

5-10cm layer

Particulars NCC HG TORIA MEAN



CD (0.05) 1.75 NS NS NS

10-20cm layer




SEm(±) 0.708 0.709 1.357 1.418


exáâÄàá

46

Fig. 4.2b. Effect of CAPS on water stable micro-aggregates (0.053-0.25mm).Treatments with same lower case letter within main plots or sub-plots were not significant at P = 0.05.

0

5

10

15

20


16.16

a

bb

c

NSNS NS

WS

A (

0.0

53

-0.2

50

mm

) [%

]

Treatments

0-5 cm

0

5

10

15

20

25


18.1

a

bbc

c

NSNS

NS

WS

A (

0.0

53

-0.2

50

mm

) [%

]

Treatments

5-10 cm

17

18

19

20

21

22

23

24


19.6

NS

NS

NS

NS

NS

NS

NS

WS

A (

0.0

53

-0.2

50

mm

) [%

]

Treatments

10-20 cm

exáâÄàá

47

4.1.3 Gravimetric Water Content (w)

The gravimetric water content across the soil profile differed significantly among

the sampling time, registering higher values at sowing that went on decreasing during

flowering and harvesting time of cover crops. The surface layer (0-5 cm) under MT

treatments exhibited significantly higher water contents both at sowing (16.5%) and

flowering (11.9%) as compared to that of CT treatments ( 14.7% and 10.5%) (Table 4.3a

i. and ii.). There was no significant variation in water contents in the surface layer during

harvesting (Table 4.3a iii.). The water contents in 5-10 cm layer (Table 4.3b) and 10-20 cm

layer (Table 4.3c) did not change significantly among treatments during each sampling time.

However, an increase in overall water contents across the profile was observed at the end of

3rd cropping cycle. In general, an increasing trend in the water contents was observed down

the depth irrespective of treatments and sampling time (Fig.4.3).

Table 4.3a(i,ii,iii) Effect of CAPS on soil moisture content (%) at 0-5cm depth 0-5cm layer

Sowing (4.3a i) Particulars NCC HG TORIA Mean

CT-M 14.23 15.24 14.52 14.67 CT-M+C 14.44 14.83 14.63 14.63 MT-M 16.03 16.35 16.29 16.22 MT-M+C 16.44 16.83 16.88 16.72 Mean 15.29 15.81 15.58 Initial 14.33 M S M within S S within M SEm(±) 0.487 0.186 0.575 0.373 CD (0.05) 1.687 NS NS NS

Flowering (4.3a ii) Particulars NCC HG TORIA Mean

CT-M 10.22 10.54 10.42 10.39 CT-M+C 10.27 10.68 10.57 10.51 MT-M 11.75 11.99 11.93 11.89 MT-M+C 11.66 12.09 12.00 11.92 Mean 10.98 11.33 11.23 Initial 10.2 M S M within S S within M SEm(±) 0.384 0.136 0.444 0.272 CD (0.05) 1.329 NS NS NS

exáâÄàá

48

Harvesting (4.3a iii) Particulars NCC HG TORIA Mean CT-M 7.14 7.53 7.33 7.33 CT-M+C 7.34 7.64 7.54 7.51 MT-M 7.61 7.94 7.83 7.79 MT-M+C 7.54 7.93 8.14 7.87 Mean 7.41 7.76 7.71 Initial 7.27 M S M within S S within M SEm(±) 0.361 0.231 0.523 0.463 CD (0.05) NS NS NS NS

Table 4.3b. Effect of CAPS on soil moisture content (%) at 5-10cm depth

5-10cm layer Sowing

Particulars NCC HG TORIA Mean CT-M 14.92 15.74 15.83 15.50 CT-M+C 15.46 15.81 15.80 15.69 MT-M 16.82 17.06 17.00 16.96 MT-M+C 16.90 17.39 17.35 17.21 Mean 16.02 16.50 16.50 Initial 14.96 M S M within S S within M SEm(±) 0.530 0.159 0.589 0.317 CD (0.05) NS NS NS NS

Flowering Particulars NCC HG TORIA Mean CT-M 10.70 11.04 11.20 10.98 CT-M+C 11.02 11.22 11.34 11.19 MT-M 12.29 12.48 12.67 12.48 MT-M+C 12.28 12.76 12.69 12.58 Mean 11.57 11.88 11.98 Initial 10.73 M S M within S S within M SEm(±) 0.456 0.150 0.518 0.301


Harvesting Particulars NCC HG TORIA Mean CT-M 7.53 8.13 7.80 7.82 CT-M+C 7.64 7.94 7.84 7.81 MT-M 8.24 8.60 8.52 8.45 MT-M+C 8.18 9.02 8.83 8.68 Mean 7.90 8.42 8.25 Initial 7.55 M S M within S S within M SEm(±) 0.337 0.163 0.429 0.327 CD (0.05) NS NS NS NS

exáâÄàá

49

Table 4.3c. Effect of CAPS on soil moisture content (%) at 10-20cm depth 10-20cm layer

Sowing




SEm(±) 0.300 0.260 0.519 0.519


Flowering




SEm(±) 0.315 0.214 0.471 0.429


Harvesting Particulars NCC HG TORIA Mean CT-M 7.82 8.30 8.13 8.08 CT-M+C 7.84 8.28 8.20 8.11 MT-M 8.79 9.13 9.02 8.98 MT-M+C 9.04 9.30 9.20 9.18 Mean 8.37 8.75 8.64 Initial 7.79


SEm(±) 0.295 0.212 0.455 0.425


exáâÄàá

50

Fig.4.3 Periodical soil moisture content across the profile

10

14

18


So

il M

ois

ture

Co

nte

nt

(%)

Treatments

SOWING0-5 cm 5-10 cm 10-20 cm

6

8

10

12

14


So

il M

ois

ture

Co

nte

nt

(%)

Treatments

FLOWERING0-5 cm 5-10 cm 10-20 cm

6

8

10


So

il M

ois

ture

Co

nte

nt

(%)

Treatments

HARVESTING0-5 cm 5-10 cm 10-20 cm

exáâÄàá

51

4.2 SOIL CHEMICAL PARAMETERS

4.2.1 Soil Reaction (pH)

The nutrient dynamics and microbial profile of a soil are influenced by soil

reaction, hence, it is considered as an important soil quality indicator.

The pH of the soils across the profile is presented in Table 4.4 and Fig.4.4.

Tillage with cropping systems did not influence the soil pH except the layers of 0-5cm.

The soil pH in the surface layer under MT system was reduced by 3.7% and 1.5%, over

the initial status (7.34) and that under CT system (7.18), respectively. Though the soil

pH did not exhibit any significant variation in the layers of 5-10 and 10-20cm, a

decreasing trend was observed in the soils under MT systems.

Table 4.4 Effect of CAPS on soil pH (1:2.5) 0-5cm layer

Particulars NCC HG TORIA Mean CT-M 7.22 7.17 7.17 7.19 CT-M+C 7.20 7.14 7.15 7.16 MT-M 7.10 7.07 7.09 7.09 MT-M+C 7.09 7.02 7.03 7.05 Mean 7.15 7.10 7.11 Initial 7.34 M S M within S S within M SEm(±) 0.029 0.033 0.061 0.066 CD (0.05) 0.1 NS NS NS

5-10cm layer Particulars NCC HG TORIA Mean CT-M 7.56 7.53 7.54 7.54 CT-M+C 7.57 7.50 7.51 7.53 MT-M 7.53 7.47 7.48 7.50 MT-M+C 7.53 7.46 7.48 7.49 Mean 7.55 7.49 7.50

Initial 7.46



exáâÄàá

52

10-20cm layer Particulars NCC HG TORIA Mean CT-M 7.60 7.59 7.59 7.59 CT-M+C 7.62 7.61 7.62 7.62 MT-M 7.61 7.51 7.51 7.54 MT-M+C 7.54 7.58 7.57 7.56 Mean 7.59 7.58 7.57 Initial 7.51 M S M within S S within M SEm(±) 0.027 0.038 0.034 0.026 CD (0.05) NS NS NS NS

Fig.4.4 pH of soils of 0-5cm depth as influenced by CAPS.Treatments with same lower case letter within main plots or sub-plots were not significant at P = 0.05.

4.2.2 Soil Organic Carbon (SOC)

Elevation in soil organic carbon due to residue retention and minimum soil

disturbances is related to physical protection of C in better preserved macro-aggregates

under MT systems. Distribution of SOC across the profile was presented in Table 4.5

and Fig.4.5. The SOC contents under MT treatments increased significantly (+27.9%

and +15.2%) over the initial status of 6.82 and 6.44 g kg-1 in the top two layers of

6.9

7

7.1

7.2

7.3

7.4


7.34

aab

bc

c

a

b b

pH

Treatments

0-5 cm

exáâÄàá

53

0-5and 5-10 cm. A reduction of SOC (-9.8% and -15.7%) was observed in CT

treatments for the same layers. The contribution of cover crops to SOC pool in the tune

of 13.0% and 2.6% over NCC (6.88 and 6.06 g kg-1) was also observed in the top layers

of 0-5 cm and 5-10 cm. The SOC contents under both CT and MT treatments did not

show any significant variations in the deeper layer of 10-20 cm.

Table 4.5 Soil Organic Carbon (g kg-1) as influenced by CAPS

0-5cm layer Par ticulars NCC HG TORIA Mean

CT-M 5.19 6.27 5.89 5.78 CT-M+C 6.38 6.71 6.43 6.51 MT-M 7.69 9.04 8.35 8.36

MT-M+C 8.26 9.95 9.05 9.08 Mean 6.88 7.99 7.43 Initi al 6.82

M S M within S S within M SEm (±) 0.139 0.110 0.227 0.221 CD(0.05) 0.48 0.32 NS

5-10cm layer Particulars NCC HG TORIA MEAN CT-M 4.79 5.49 5.35 5.21 CT-M+C 5.52 5.75 5.65 5.64 MT-M 6.68 7.45 7.15 7.09 MT-M+C 7.15 8.12 7.94 7.74 Mean 6.04 6.70 6.52 Initial 6.44 M S M within S S within M SEm(±) 0.137 0.094 0.205 0.188 CD (0.05) 0.47 0.27 NS NS


exáâÄàá

54

Fig. 4.5 Soil Organic Carbon (g kg-1) as influenced by CAPS.Treatments with same lower case letter within main plots or sub-plots were not significant at P = 0.05

0

2

4

6

8

10


6.82

dc

ab

c

ab

Org

an

ic C

arb

on

(g

kg

-1)

Treatments

0-5 cm

0

1

2

3

4

5

6

7

8


6.44

cc

ba

ba a

Org

an

ic C

arb

on

(g

kg

-1)

Treatments

5-10 cm

4.4

4.5

4.6

4.7

4.8

4.9

5

5.1


4.72NS

NSNS

NS

NS

NS

NS

Org

an

ic C

arb

on

(g

kg

-1)

Treatments

10-20 cm

exáâÄàá

55

4.3 SOIL MICROBIAL ATTRIBUTES

Gradual build up and restoration of SOC under reduced tillage system elevated

the microbial population and microbial biomass carbon (MBC) significantly in the

surface layers.

4.3.1 Microbial Population

4.3.1.1 Population of Bacteria

The population of bacteria in different layers was enhanced as compared to the

initial status at the end of the 3rd cropping year (Table 4.6). In the surface layer (0-5 cm)

an increase of 61.2% and 23.0% over the initial population of 17.6 × 106cfu g-1 was

observed in MT and CT treatments (Fig.4.6a), respectively. Similar trend was also

observed in the layer of 5-10 cm (Fig.4.6b) and no significant changes in bacterial

population could be noticed among treatments below the depth of 10 cm. Higher

amounts of organic matter in MT soils increased the bacterial abundance significantly to

the tune of 31.0% and 25.5% over the CT soils in the top two layers (0-5 cm and 5-10

cm). Again, practice of cover crops enhanced the bacterial proportion by 21.8% and

20.1% over no cover crop treatments (NCC) in the layers of 0-5 cm, and 5-10 cm,

respectively.

Table 4.6 Bacterial population (× 106cfu g-1) as influenced by CAPS

0-5cm layer Particulars NCC HG TORIA Mean CT-M 17.00 21.00 20.67 19.56 CT-M+C 21.33 26.00 23.33 23.56 MT-M 22.67 29.00 28.33 26.67 MT-M+C 26.00 33.00 31.00 30.00 Mean 21.75 27.25 25.83 Initial 17.56 M S M within S S within M SEm(±) 0.485 0.450 0.881 0.900 CD (0.05) 1.68 1.31 NS NS

exáâÄàá

56

5-10cm layer Particulars NCC HG TORIA Mean CT-M 14.33 19.33 18.33 17.33 CT-M+C 20.33 23.00 22.33 21.89 MT-M 21.33 24.67 23.33 23.11 MT-M+C 22.00 28.67 27.67 26.11 Mean 19.50 23.92 22.92 Initial 14.66


CD (0.05) 2.37 2.07 NS NS

10-20cm layer




SEm(±) 0.337 0.523 0.918 1.046


4.3.1.2 Population of Fungi

Differential status of organic matter among treatments influenced the population

of fungi in the soil (Table 4.7 and Fig. 4.7). The soils under MT registered the maximum

fungal population and gain was of 36.8% and 28.2% over the initial values (11.8 and 9.4

× 104cfu g-1) in the layers of 0-5 cm and 5-10 cm, respectively. The treatments under CT

also exhibited an increase of 12.1% and 8.1% over the initial status (base year) in the top

two layers. Cover cropping also enhanced the fungal population in the tune of 15.1% in

0-5 cm layer and 13.6% in 5-10 cm layer over NCC treatments. The fungal population in

10-20 cm layer did not show significant changes among various treatments.

exáâÄàá

57

Fig. 4.6a

Fig. 4.6b

Fig. 4.6 Bacterial population (× 106cfu g-1) as by different CAPS. Treatments with same lower case letter within main plots or sub-plots were not significant at P = 0.05.

10

12

14

16

18

20

22

24

26

28

30


17.56

d

c

b

a

c

ab

Ba

cte

ria

po

pu

lati

on

( ×

10

6cf

u g

-1)

Treatments

0-5 cm

10

12

14

16

18

20

22

24

26

28


14.66

c

b

b

a

b

aa

Ba

cte

ria

po

pu

lati

on

( ×

10

6cf

u g

-1)

Treatments

5-10 cm

exáâÄàá

58

Table 4.7 Population of fungi (× 104cfu g-1) as influenced by CAPS

0-5cm layer




CD (0.05) 1.15 1.11 NS NS

5-10cm layer




CD (0.05) 1.40 0.56 NS NS

10-20cm layer




SEm(±) 0.313 0.218 0.474 0.436


exáâÄàá

59

Fig. 4.7 Fungal population (× 104cfu g-1) asinfluenced by different CAPS.

Treatments with same lower case letter within main plots or sub-

plots were not significant at P = 0.05.

8

9

10

11

12

13

14

15

16

17


11.77

b

b

a

a

b

a

a

Fu

ng

al

po

pu

lati

on

( ×

10

4cf

u g

-1)

Treatments

0-5 cm

6

7

8

9

10

11

12

13


9.44

c

bc

ab

a

b

aa

Fu

ng

al

po

pu

lati

on

( ×

10

4cf

u g

-1)

Treatments

5-10 cm

exáâÄàá

60

4.3.1.3 Population of Actinomycetes

The population of actinomycetes under different treatments across the profile

was presented in Table 4.8 and Fig.4.8. Accumulation of residue inputs under MT

treatments enhanced the actinomycetes population by 34.6% and 25.3% over the initial

status (12.56 & 10.77 × 106cfu g-1) in the layers of 0-5 cm and 5-10 cm, respectively.

Soils of these two layers under MT treatments also registered significantly higher

population of actinomycetes (19.6 % and 17.4 %) over CT treatments. Growing of

follow-up cover crops enhanced the actinomycetes population in the tune of 12.2 % and

8.3 % over the NCC treatments (14.35 and 11.91 × 106cfu g-1) in the top two layers. No

significant difference in the status of actinomycetes population could be observed

among treatments in the bottom layer (10-20 cm).

Table 4.8 Population of actinomycetes (× 106cfu g-1) as influenced by CAPS



exáâÄàá

61


Fig.4.8 Population of actinomycetes (× 106cfu g-1) as influenced by different CAPS

8

10

12

14

16

18


12.56

b

b

aa

b

aa

Act

ino

my

cete

s p

op

ula

tio

n (

×1

04

cfu

g-1

)

Treatments

0-5 cm

6

7

8

9

10

11

12

13

14


10.77b

b

a

a

b

a a

Act

ino

my

cete

s p

op

ula

tio

n (

×1

04

cfu

g-1

)

Treatments

5-10 cm

exáâÄàá

62

4.3.2 Microbial Biomass Carbon (MBC)

The microbial biomass carbon (MBC) increases much more readily due to

changes in tillage system or residue supply and the increase is more conspicuous in the

tope few centimeters due to concentrated C input near the soil surface. The soil MBC of

different treatments across the soil depths were presented in Table 4.9, and

Fig.4.9.Establishment of MT systems significantly enhanced the MBC of soils by

115.1% and 66.5% over the initial status of 82.3 and 78.6 µg C g-1 in the layers of 0-5

cm and 5-10 cm, respectively and the corresponding increase over CT treatments were

88.1% and 49.9%. Accumulation of crop residues through cover crops elevated the

MBC of soils by 21.5% and 14.3% as compared to NCC treatments (118.5 and 99.6 µg

C g-1) in the top two layers (0-5 and 5-10cm). The MBC of soils under different

treatments increased from surface to downwards and at 10-20 cm layer, no significant

variations could be observed.

Table 4.9 Impact of CAPS on soil MBC (µg C g-1)

0-5cm layer


CT-M 74.53 96.77 89.47 86.92

CT-M+C 93.23 108.67 101.80 101.23

MT-M 146.07 177.40 163.37 162.28

MT-M+C 160.10 219.17 195.70 191.66

Mean 118.48 150.50 137.58

Initial 82.3


SEm(±) 3.175 3.195 6.107 6.389

CD (0.05) 10.98 9.32 NS NS

exáâÄàá

63


10-20cm layer


CT-M 76.4 79.4 78.3 78.0 CT-M+C 79.3 82.2 81.1 80.9 MT-M 70.3 73.2 74.1 72.5 MT-M+C 72.1 79.7 77.7 76.5 Mean 74.5 78.6 77.8 Initial 74.7 M S M within S S within M SEm(±) 1.976 1.254 2.846 2.508 CD (0.05) NS NS NS NS

4.3.3 Microbial Quotient

The microbial quotient is the ratio of MBC to SOC expressed as ratio or

percentage and it is very often used as a measure of C availability to micro-organisms.

The microbial quotients from the soils of different layers were presented in Table 4.10,

and Fig.4.10. In the surface layer (0-5 cm), the microbial quotient of MT treatments

were higher (2.03%) than CT treatments (1.53%) and that of cover crop treatments

(1.83%) were more than NCC treatments (1.68%). Similar trend was also observed in

the layer of 5-10 cm. But the microbial quotient of the soils of the bottom layer (10-20

cm) exhibited a reverse trend with the higher values in CT treatments (1.68%) as

compared to MT treatments (1.51%). There was very little variation in the values of

microbial quotient between cover crops and NCC treatments in the bottom layer.

exáâÄàá

64

Fig.4.9 Microbial Biomass Carbon (µg of C g-1) as affected by CAPS.Treatments with same lower case letter within main plots or sub-plots were not significant at P = 0.05

0

50

100

150

200


82.3 dc

b

a

c

ab

MB

C (

µg

C g

-1)

Treatments

0-5 cm

0

20

40

60

80

100

120

140


78.6c

c

ba

c

a b

MB

C (

µg

C g

-1)

Treatments

5-10 cm

68

70

72

74

76

78

80

82


74.7

NS

NS

NS

NS

NS

NSNS

MB

C (

µg

C g

-1)

Treatments

10-20 cm

exáâÄàá

65

Table4.10Microbial quotient (MBC/SOC) [%] as influenced by CAPS

Fig.4.10 Microbial quotient across the profile as influenced by CAPS.Treatments with same lower case letter within main plots or sub-plots were not significant at P = 0.05.

4.4 Maizeequivalent yield (MEY)

Significant variations in maizeequivalentyield(MEY) among tillage and

cropping systems were observed at the end of 3rd cropping year (Table 4.11 andFig.

4.11). Even though the maximum MEY was obtained from MT with

1.40

1.50

1.60

1.70

1.80

1.90

2.00

2.10

2.20

CT-M CT-M+C MT-M MT-M+C NCC HG TORIA

M-q

uo

tie

nt

(MB

C/S

OC

) [

%]

Treatments

0-5 cm 5-10 cm 10-20 cm

Treatments 0-5cm 5-10cm 10-20cm

Main plot

CT-M 1.50 1.60 1.67

CT-M+C 1.55 1.62 1.68

MT-M 1.95 1.76 1.50

MT-M+C 2.10 1.77 1.51

Sub-plot

NCC 1.69 1.64 1.57

HG 1.84 1.72 1.60

TORIA 1.81 1.70 1.61

exáâÄàá

66

maize + cowpea intercrop (105.84q ha-1), there was no significant

difference between MT and CT either withsolemaize or with maize + cowpea

intercrop. Inclusion of horsegram (HG) and toria as cover crops in dry season

increased the MEY significantly over fallow (NCC) and the increase was in the tune

of 20.3% and 29.9%, respectively. The maximum MEY of 114.39 q ha-1was produced

from the treatment MT-M+C-TORIA, followed by CT-M+C-TORIA (113.93q ha-1).

Table 4.11EffectofCAPS on MaizeEquivalent Yield(qha-1)


CT-M 48.79 67.51 71.66 62.65

CT-M+C 90.75 106.44 113.93 103.70

MT-M 48.60 63.01 70.57 60.73

MT-M+C 97.04 106.08 114.39 105.84

Mean 71.29 85.76 92.64


SEm(±) 1.567 0.970 2.227 1.939

CD(0.05) 5.42 2.83 NS NS

Fig. 4.11 Effect of different CAPS on Maize Equivalent Yield (q ha-1).Treatmentswith same lowercase letter within main plots or sub-plots were not significant at P=0.05

0

20

40

60

80

100

120

CT-M CT-M+C MT-M MT-M+C NCC HG TORIA

b

a

b

a

c

ba

Yie

ld (

q h

a-1

)

Treatments

exá

âÄàá

67

CT 6.15

5.43

4.74

MT 8.72

7.42

4.9

4 5 6 7 8 9 10

0-5.

5-10.

10-20.

SOC (g kg-1)

Depth (cm)

CT 55.1

49.8

42.9

MT 66.9

59.1

46.1

35 40 45 50 55 60 65 70

0-5.

5-10.

10-20.

WSA [> 0.25 mm] (%)

Depth (cm)

CT 18.4

20

22.6

MT 14.8

16.4

20.4

12 17 22 27

0-5.

5-10.

10-20.

WSA(.053-.25mm) [%]

Depth (cm)

Fig. 4.12a Depth wise graph showing the distribution of SOC, WSA under different tillage systems

exá

âÄàá

68

CT 1.53

1.61

1.68

MT 2.02

1.77

1.51

1 1.2 1.4 1.6 1.8 2 2.2

0-5.

5-10.

10-20.

Micrbial Quotient (%)

Depth (cm)

CT 94.1

87.3

79.5

MT 177

130.9

74.5

60 100 140 180

0-5.

5-10.

10-20.

MBC (µg g-1)

Depth (cm)

Fig. 4.2b Depth wise graph showing the distribution of MBC and Microbial Quotient under different ti llage systems

DiscussionDiscussionDiscussionDiscussion

69

DISCUSSION

Sustainable soil management warrants not only proper choice of tillage

techniques, cropping methods, plus ensuring a supply of nutrients; but also

subsequent soil quality evaluations. The beneficial role of Conservation Agriculture

Production System (CAPS) on soil health is well-established world over. Some

promising and interesting results have been obtained from the present study and the

relevant discussion is established below.

5.1 BULK DENSITY

The results indicated an overall reduction of soil BD under MT systems with

cover crops which are restricted to surface layers of 0-5 cm and 5-10 cm. this

remarkable decrease of BD is likely to be a reflection of considerable increase in

SOM content induced by accumulation of litter inputs over the years on the soil

surface, which corroborates the results observed by Fengyan et al., (2011) and

Arvidson (1998). SOM has a direct impact on the BD of soil or inversely on the

porosity, as the particle density of organic matter is considerably than that of the

mineral soil; furthermore, soil organic matter is often associated with increased

aggregation and permanent pore development as a result of soil biological activity

(Jemai et al., 2013). The higher BD in the top layer under CT systems may be

attributed to the loss of finer particles induced by water erosion and low SOM leading

to less aggregation (Lafond et al., 2011). The higher soil BD in 10-20 cm layer

remains unaffected due to low and lack of variations in SOM contents. The significant

negative correlation of SOC with BD with ‘r’ of -0.85** and -0.89** in the layers of0-5

and 5-10 cm, respectively justifies the favourable influence of SOC on soil BD

(Fig. 5.1).


70

Fig.5.1Correlation of SOC with soil BD

5.2 WATER STABLE AGGREGATES

Soil structure is a key indicator in edaphic systems and the ability of the soil to

sustain the biota. Aggregation stability is an indicator of soil structure and is measured

mostly by means of SOC and soil biota. SOC acts as a central nucleus in formation of

soil aggregates, while the biota and their organic products contribute to the

development of soil structure (Sandoval et al., 2008).

The higher proportion of macro-aggregates (>0.25mm) concomitant with

lower proportion of micro-aggregates (0.053-0.25mm) observed in the surface soils

(0-5 cm) and subsoil (5-10 cm) under MT is related to reduced physical impact

y = -0.022x + 1.479

R² = 0.723

1.20

1.24

1.28

1.32

1.36

1.40

1.44

4.00 5.00 6.00 7.00 8.00 9.00 10.00 11.00

BD

(M

g m

-3)

Organic Carbon (g kg-1)

0-5 cm

y = -0.029x + 1.557

R² = 0.787

1.28

1.32

1.36

1.40

1.44

4.00 5.00 6.00 7.00 8.00 9.00 10.00

BD

(M

g m

-3)


5-10 cm


71

leading to lower aggregate turnover rates. Intensive disturbance of the top layer under

CT, in contrast, disrupts macro-aggregates (Six et al., 2000a, Zotarelli et al., 2007).

The higher inputs of fresh organic in MT with cover crops induces increased

microbial activity and production of microbial binding agents leading to the formation

of higher macro-aggregate in the top two soil layers (Mikha and Rice, 2004; Jacoba et

al., 2009). The proportion of soil aggregates in 10-20 cm layer under both MT and CT

is related to the contents of organic matter rather than tillage methods thatcorroborate

the findings of Zhou Hu et al., 2007. The strong positive correlation (r = 0.90** and

0.76** ) of SOC with macro-aggregates in the layers of 0-5 cm and 5-10 cm indicates

the significance of SOC in formation of macro-aggregates (Fig.5.2). The negative

correlation (r = -0.77** and -0.71** ) of SOC with micro-aggregates is related to lower

turnover of macro-aggregates (Fig.5.3).

Fig.5.2 Correlation of SOC with water stable macro-aggregates

y = 4.399x + 28.31

R² = 0.804

30

40

50

60

70

80

90

4 5 6 7 8 9 10 11

WS

A ,

>0

.25

mm

(%

)


0-5 cm

y = 4.139x + 27.88

R² = 0.574

30

40

50

60

70

80

4 5 6 7 8 9 10

WS

A ,

>0

.25

mm

, (%

)


5-10 cm


72

Fig.5.3 Correlation of SOC with water stable micro-aggregates

5.3 Soil Moisture Content

Beneficial effects of crop residues maintenance on the soil surface under

conservation tillage include increased water conservation and soil aggregation

(Hubbard et al., 2013). In the dry period (Rabi season), the amount of water in the

soil reduce gradually irrespective of tillage practices and soil layers as rainfall do not

influence soil water pattern. Tillage reduction in associationwith residue retention

significantly increased the moisture contents in the surface layers mainly due to large

increase in SOC (Kushwaha et al., 2001, Pankhurst et al., 2002, Daraghmeh et al.,

2009). Soil disturbance can also lead to a less stable pore system and pore aggregate

y = -1.445x + 27.37

R² = 0.589

5

10

15

20

25

4 5 6 7 8 9 10 11

WS

A,

0.0

53

-0

.25

mm

(%

)


0-5 cm

y = -1.780x + 29.63

R² = 0.503

5

10

15

20

25

30

4 5 6 7 8 9 10

WS

A,

0.0

53

-0.2

5 m

m (

%)


5-10 cm


73

development that reduce soil moisture contents and regular tillage also enhances

direct evaporation of water from soil surface (Guto et al., 2012). The role of SOC on

soil moisture contents in the surface layers justified by its strong correlation with the

later during sowing (r = 0.82** ) and flowering (r = 0.82** ). Lack of variations in

tillage practices at the deeper layers (5-10 and 10-20 cm) may be related to poor

aggregation and pores because of low SOC contents.

Fig. 5.4 Correlation of SOC with soil moisture content at sowing and flowering at 0-5cm soil depth.

y = 0.685x + 10.46

R² = 0.679

12.00

13.00

14.00

15.00

16.00

17.00

18.00

4.00 5.00 6.00 7.00 8.00 9.00 10.00 11.00

So

il M

ois

ture

Co

nte

nt

(%)


Sowing

y = 0.524x + 7.281

R² = 0.672

8.00

9.00

10.00

11.00

12.00

13.00

14.00

4.00 5.00 6.00 7.00 8.00 9.00 10.00 11.00

So

il M

ois

ture

Co

nte

nt

(%)


Flowering


74

5.4 SOIL REACTION (pH)

The elevation of SOM in the soil surface through residue incorporation

reduced the soil pH in MT systems, which might be related to production of organic

acids as a result of microbial decomposition of organic matter (Logan et al., 1991,

Kern et al., 1993). The acidifying effect on soils under MT due to SOC has also been

reported by Thomas et al., 2007. The significant negative correlation (r = -0.60** )

between SOC and soil pH in the top soils justifies the above findings (Fig.5.5).

Fig. 5.5 Correlation of SOC with pH in 0-5cm soil layer

5.5 SOIL ORGANIC CARBON (SOC)

The combined effect of MT and residue retention or the accumulation of SOC

is greater than the effects of either MT or residue retention alone. In MT, the organic

matter is incorporated faster in the top few centimeters of soil than in CT, where it is

redistributed up to a depth of 20 cm. (Kushwaha et al., 2001)

Considerable buildup of SOC in MT treatments with cover crop in the top two

layers is attributed to greater residue input (5.5 to 6.5 t ha-1of biomass) as well as

lower biological oxidation due to less tillage induced soil inversion (Hel et al.,2009).

Higher SOC contents due to absence of soil redistribution were also observed by

Jemai et al., 2013. Lower physical impacts under MT systems increase aggregate

y = -0.043x + 7.444

R² = 0.365

6.85

6.95

7.05

7.15

7.25

7.35

4.00 5.00 6.00 7.00 8.00 9.00 10.00 11.00

pH

(1

:2.5

)

Organic C (g kg-1)

0-5cm


75

stability resultingin lower aggregate turn over, therefore improved physical protection

of aggregate SOC from decomposition and thus higher SOC stocks. The higher

degradation of macro-aggregate induced by intense soil disturbances in CT system

exposed the formerly incorporated SOC stocks to microbial decomposition (Zotalleri

et al., 2007, Tan et al., 2007) in the top layers. Protection of SOC because of higher

proportion of macro-aggregates under MT systems also corroborates the findings of

Plaza-Bonilla et al., 2013. In the bottom layer (10-20 cm), the effect of surface

accumulated residue on SOC is minimum under MT system whereas in CT system

soil inversion results an even distribution of SOC.

5.6 Microbial Biomass Carbon (MBC)

Microbial Biomass Carbon is considered as a sensitive indicator of soil quality

and is closely related to soil fertility. In contrast to inversion tillage (CT), crop

residues in minimum tillage (MT) are left on or near the soil surface, where they

undergo decomposition. Accumulation of concentrate C input in the top few

centimeters results an increase in MBC near the soil surface and it increases much

more readily due to changes in tillage system or residue supply than SOC (Stockfisch

et al., 1999). The higher MBCin the top layers (0-5 and 5-10cm) of MT than that of

CT corroborates the above findings. Balota et al. (2004) have reported that the fresh

SOM at the surface moderates the soil temperature and moisture that is conducive to

microbial activity and higher MBC.

From the contrasting profiles of MBC observed in MT and CT systems, it may

be deduced that the high SOC near the soil surface is maintained or that the

enrichment will be even continued. In the deeper MT layers (10-20cm), low MBC

values indicate a decline in SOM contents. Similar relations of SOC with MBC in


76

contrasting tillage systems were reported by Doran (1987) and Carter (1991). The

contribution of SOC to MBC is justified by their significant positive correlation (r =

0.98** and 0.99** ) in the layers of 0-5 and 5-10cm (Fig.5.6).

The ratio of MBCto SOC is termed as microbial quotient and is a measure of

C availability to microorganisms. In the top layers of 0-5 and 5-10cm of MT, the

MBC/SOC ratio is much higher suggesting higher substrate availability through the

accumulation of crop residues in the surface soil (Jacobs et al., 2009). On the other

hand, in deeper layers (10-20cm) of MT, the microbial quotient is relatively low

indicating ongoing decline in SOM concentration (Stockfisch et al., 1999) and the

increase of this ratio down the profile in CT may be related to an even distribution of

SOC induced by tillage.

Fig.5.6 Correlationof SOC with MBCofthe soils

y = 31.12x - 95.81

R² = 0.964

40.0

80.0

120.0

160.0

200.0

240.0

4.00 5.00 6.00 7.00 8.00 9.00 10.00 11.00

MB

C (

µg

C g

-1)


0-5 cm

y = 22.54x - 35.05

R² = 0.976

60

80

100

120

140

160

4 5 6 7 8 9

MB

C (

µg

C g

-1)


5-10 cm


77

5.7 Microbial Population

Soil microbial biomass, even though represents only a small proportion of

overall SOM, it is more dynamic than total SOM and a better indicator of how tillage

and cropping systems impact soil health and productivity (Hamelet al., 2006).

Increased soil organic matter content associated with reduced tillage practices

enhanced the population of bacteria, fungi and actinomycetes up to a depth of 0-10cm

under MT, which could be related to availability of higher amounts of substrates for

microorganisms (Mikanova et al., 2009, Sun et al., 2011). Deeper in the soil profiles

(10-20cm), the negligible difference between the tillage treatments is due to lower and

even distribution of SOC in MT and CT, respectively. One explanation for the effect of

MT on microbial biomass is that low-tilled soils provide a more favourable habitat for

microorganisms (Balota et al., 2004). The significant positive correlation of SOC with

population of bacteria (r = 0.91** and 0.77** ) (Fig.5.7), fungi (r = 0.86** and 0.88** )

(Fig.5.8) and actinomycetes (r = 0.87** and 0.86** ) (Fig. 5.9) indicates the favourable

influence of SOC to these microbial community in the top layers (0-5 and 5-10cm).

y = 2.945x + 3.051

R² = 0.821

10.0

15.0

20.0

25.0

30.0

35.0

40.0

4.00 5.00 6.00 7.00 8.00 9.00 10.00 11.00

Ba

cte

ria

po

pu

lati

on

( ×

10

6cf

u g

-1)


0-5 cm


78

Fig. 5.7 Correlation between SOC with bacterial population the soils

Fig. 5.8 Correlation between SOC with fungal population of the soils

y = 2.904x + 3.462

R² = 0.588

10.0

15.0

20.0

25.0

30.0

35.0

4.00 5.00 6.00 7.00 8.00 9.00 10.00

Ba

cte

ria

po

pu

lati

on

( ×

10

6cf

u g

-1)


5-10 cm

y = 1.212x + 5.626

R² = 0.731

8.00

10.00

12.00

14.00

16.00

18.00

20.00

4.00 5.00 6.00 7.00 8.00 9.00 10.00 11.00

Fun

gi

po

pu

lati

on

( ×

10

4cf

u g

-1)


0-5 cm

y = 1.134x + 3.828

R² = 0.774

8

9

10

11

12

13

14

15

4.00 5.00 6.00 7.00 8.00 9.00 10.00

Fun

gi

po

pu

lati

on

( ×

10

4cf

u g

-1)


5-10 cm


79

Fig. 5.9 Correlation of SOC with actinomycetes population of the soils

5.8 Maize Equivalent Yield (MEY)

The MEY in MT systems, though are at par with that of CT system,

marginal increase of MEY in MT may be related to considerable buildup of SOM

that moderates the aggregation, moisture retention, microbial profile and the

dynamics of nutrient mobility at the end of 3rd cropping cycle. The intercrop of

maize and cowpea under both MT and CT systems increased the MEY over sole

maize because of additional gain from cowpea. The elevated MEY due to inclusion

of toria as cover crop is attributed to the higher selling price of mustard.

y = 1.104x + 7.302

R² = 0.748

10.00

12.00

14.00

16.00

18.00

20.00

4.00 5.00 6.00 7.00 8.00 9.00 10.00 11.00

Act

ino

my

cete

s p

op

ula

tio

n (

×1

06

cfu

g-1

)


0-5 cm

y = 1.091x + 5.531

R² = 0.744

8.00

10.00

12.00

14.00

16.00

4.00 5.00 6.00 7.00 8.00 9.00 10.00

Act

ino

my

cete

s p

op

ula

tio

n (

×1

06

cfu

g-

1)


5-10 cm

fâÅÅtÜç tÇw VÉÇvÄâá|ÉÇ

80

SUMMARY AND CONCLUSION

Conservation agriculture production system (CAPS) with the components of

minimum tillage, legume based intercropping and follow up cover crop has been

established at RRTTS, (OUAT) Kendujhar located in the degraded rainfed agro-

ecosystem under North Central Plateau zone of Odisha during 2011, in split plot

design, with an objective to conserve the natural resources and to keep it buffered

against risks. The treatment details are Conventional tillage (CT) and Minimum

tillage (MT) with sole Maize (M) and inter crop Maize + Cowpea (M+C) in main-

plots during wet season and Horsegram (H), Toria (T) and no cover crop (NCC) in

sub-plots during dry season. The impact of CAPS on soil attributes is assessed after

completion of the 3rd cropping cycle in the present study “Soil attributes as influenced

by maize based Conservation Agriculture Production System (CAPS) in a Fluventic

Haplustepts under North Central Plateau zone of Odisha” and the salient findings are

as follows:

� Tillage reduction (MT) lowered the soil BD in the tune of 3.4% and 2.6% over

the initial status (1.32 Mg m-3 and 1.37 Mg m-3) in 0-5 and 5-10cm layers,

respectively, whereas these soils under CT exhibited higher BD (+1.5%,

+2.2%). Cover cropping also reduced the soil BD by 1.3% and 1.0% over

NCC (1.32 Mg m-3 and 1.38 Mg m-3) in the top two layers.

� Higher proportion of macro-aggregates were formed in the surface and

subsurface layers under MT (+14.9%, +11.9%) as compared to CT (-5.3%,

-5.7%). The top soil’s micro-aggregates content on the other hand exhibited a

reverse trend with the higher values in CT (+5.9%, +4.3%) than those of MT

(-14.8%, -14.8%).


81

� The MT systems have higher water contents at sowing (16.5%) and flowering

(11.9%) times of dry season cover crops as compared to CT systems (14.7%

and 10.8%).

� The soil pH in the surface layer under MT systems was reduced by 3.7% and

1.5% over the initial status (7.34) and that under CT systems (7.18).

� The SOC contents under MT treatments increases considerably (+27.9% and

15.2%) over the initial status of 6.82 g kg-1 and 6.44 g kg-1 in the top two

layers of 0-5 and 5-10cm, whereas a reduction of SOC (-9.8%, and -15.7%)

were observed in CT treatments for the same layers. Growing of cover crops

also enhanced the SOC of soils by 13.0% and 2.6% over NCC (6.88 and 6.06

g kg-1) in the top two layers.

� An elevation in the population of bacteria (+31.0%, 25.5%), fungi (+22.0%,

+18.6%) and actinomycetes (+19.6%, +17.4%) in the soils under MT systems

over CT systems were observed in the layers of 0-5cm and 5-10cm. the

practice of cover crops also increased the bacterial (+21.8%, +20.1%), fungal

(+15.1%, +13.6%) and actinomycetes (+12.2%, +8.3%) population over NCC

in the top two layers.

� Adoption of MT systems significantly elevated the MBC of soils (+88.1%,

+49.9%) over CT systems in the surface (0-5cm) and subsurface (5-10cm)

layers. Cover cropping also contributed significantly to the MBC pools

(+21.5%, 14.3%) of the corresponding layers.

� The microbial quotient was obtained in systems were in the order MT (2.03%)

> CT (1.53%) and cover crops (1.83%) > NCC (1.69%) in 0-5cm layer,

whereas, the deeper layers (10-20cm), exhibited a reverse trend with higher

values in CT (1.68%) as compared to MT (1.51%).


82

� The maize equivalent yield (MEY) did not vary significantly among MT and

CT either with sole maize or with maize+cowpea intercrop. Cover crops of

horsegram and toria increased the MEY by 20.3% and 29.9%, respectively

over NCC. The maximum MEY of 114.39 q ha-1 was produced from the

treatment of MT – M + C – TORIA.

CONCLUSION

Contrasting land management practices resulted in distinctly different effects

on soil condition for the top 0-10 cm depth. The conservation agriculture production

system (CAPS) with the primary principles of minimum tillage, maize – cowpea

intercrop and cover crops of horsegram, alters the depth distribution and concentration

of SOC. The decrease in soil BD, low turnover of macro aggregates, high soil

moisture content and elevated MBC, microbial quotient and microbial diversity are

directly related to considerable build-up of SOC induced by surface accumulation of

crop residues promoted by conservation tillage (MT) management. Rapid depletion of

formerly incorporated SOC through biological oxidation because of continuous

exposure and redistribution of soils across the profile in CT systems imports an

adverse effect on overall soil quality. The trends in soil organic matter related

properties in the present study, indicates continuous cropping in minimum tillage are

creating a more favourable plant growth environment relative to crop sequence with

fallow in conventional tillage can be an adoptable intervention to sustain yields and

soil health in the degraded rainfed agro-ecosystems under North Central Plateau zone

of Odisha. However, information on aggregate size carbon will reflect the true

dynamics of carbon sequestration in conservation agriculture production systems.

U|uÄ|ÉzÜtÑ{ç

i

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