UNIVERSITI PUTRA MALAYSIA

INFLUENCE OF SLOW-RELEASE FERTILISERS ON GROWTH OF RUBBER (HEVEA BRASILIENSIS) SEEDLINGS

TONG VIET THINH

FP 1997 16

INFLUENCE OF SLOW-RELEASE FERTILISERS ON GROWTH OF RUBBER (HEVEA BRASILIENSIS) SEEDLINGS

By

TONG VIET TIllNH

Thesis Submitted in Fulfilment of the Requirements for the Degree of Master of Agricultural Science in the Faculty of Agriculture,

Universiti Putra Malaysia

June 1997

ACKNOWLEDGEMENTS

I would like to express my grateful thanks and great appreciation to

Prof Dr. Sharifuddin Haji Abdul Hamid, chairman of the supervisory

committee for his very precious guidance and advice during my course of

research. I also would like to extend my heartfelt thanks for the extremely

valuable admonition and suggestion from members of the supervisory

committee, Assoc. Prof Dr. Zaharah Abdul Rahman, Dr. Mohd. Yusoff Bin

Mohd. Noor and Dr. Mahmud Abdul Wahab.

To the Rubber Research Institute of Vietnam and the World Bank, who

provided me a good chance of fostering my professional knowledge by

providing financial support and arranging the favourable conditions of the

study, lowe them more than the traditional word of thanks. Personally, my

dearest gratitude are also due to Mr. Mai Van Son, Director, Rubber Research

Institute of Vietnam, and Mr. Christopher E. W. Arnold, Training Adviser,

Agricultural Rehabilitation Project, World Bank.

For those who helped me, directly or indirectly, to complete my work

satisfactorily, their names are heartily engraved in my mind. I also wish to

express my sincere thanks for the warm welcome and enthusiastic help

11

rendered by the persons with whom I took counsel, contacted and worked in

the laboratories, departments, divisions, administration offices, financial units

and others at UPM, RRIM and RRIV.

I thank all of my friends for their kind support and care in relation to

my work. Finally, as my best friends, I especially wish to manifest a deep

gratitude to my wife and children for strengthening me with their immutable

and sweet love.

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TABLE OF CONTENTS

Page

ACKNOWIEDGMENT . .. . . . ... . . . . . . '" ... ... ... ... ... ... ... ... ... ... ... ... ... ... 11 LIST OF TABIES ... ........... .................. ....... ..... .............................. . . . '" ..... VI LIST OF FIGURES ............................................................................. .. , ... . x LIST OF ABBREVIATIONS .... . ...... ...... ...... ....... ......... ........ ......... .......... ... Xl ABS'fRACT .... .. . .................... ...................... .. ........... ... ..... .............. ....... ... XlI ABS'fRAK ..... .......................... . .............. . . ............ . . . . ........ . . . . . . . . . . . . . . . . .. ... . .. xv

CHAPTER

I IN1RODUCTION ...... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

IT REVIEW OF LITER.A TURE ........ .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Classification of Slow-release Fertilisers ..... ......... . . . . . . . . . . . . . . . . . . . . 4

Slowly Soluble Fertilisers .................... .......... ................. . 6 Coated Fertilisers ..... ....... . .... ........ .................. . . . ............. .. 6 Nitrification Inhibitor-mixed Fertilisers .. ....... .... . . . . . .. . . . . . . . 8

Crop Objects Used in Slow-release Fertiliser Studies .. .. . .......... 10 Woody Plants . ... ......... ... ................. .......... ............. ....... .. 1 0 Fruit Trees ... ........ . .... . . ......... ...... ..... ... .... ..................... '" . 11 Cereal Crops ................. .... .... ................ . ..... .............. .. . . . 1 2 Vegetables . ................ .. .............. .......... .... ..... ..... ... . .. .. . . . .. 12 Flowers ................ ...... ...... .... .... ........ .. .... ..... . ... . .. .. . ....... . . . 14

Some Results from Past Slow-release Fertiliser Studies... ... . . . 14 Release of Slow-release Fertilisers .. ...... . ................. ....... 14 Nutrient Uptake by Plants from Slow-release Fertilisers 17 Effects of Slow-release Fertilisers on Growth and Yield of Plants ..................... .... . . ........................ ........... ...... . . . .. 19

ill MA 1ERIALS AND METHODS .................................. ....... . .. 23 Soil-incubation Experiment ................................................. . . . 27

Treatments . . ........ ..................... ............. ...... .... .. ......... . . . . 27 Materials and Management .................. ...... . .. . . . . . . . . . . . . . . . . 28 Fertiliser Decomposition ............................................... 29 Fertiliser Analyses ..... ....... ................. . . . . ... .... ....... .. ....... . 30 Soil Analyses . ... ..... .. .. ...... .... ................ ...... ........ ... . . . . . . . . 3 1 Nutrient Accumulation in Soil from Fertilisers .. .. ......... 33 Data Processing ........ . ............. .............. ... ...... .... .. . . . . . . . . . . 33

IV

Glass-house Experiment ... ....................................... ............... 35 Treatments .......... . . . . . . .. . .. . . .... ... .... ......... .... . . . . .. . ..... . . . . . '" . 35 Material s and Management...... ....... ...... .... .......... ..... ...... 37 Fertil iser Analyses . .. . .. .. ..... .. .. ... .. .. .. ... . . . .. ...... .. .......... ... . . 38 Soil Analyses . ........ ............ . . ..... . . .. . .. ... .. .. ... .... . . . .... .. . ... .. 39 Plant Tissue Analyses .. ...... ..... .......... ...... ...... ......... ........ 39 I� Appl ication and Calculation . .. .. ... . .... ...... ...... ........... 41 Growth Parameters ...... .. ... . . . .. .. ... .... . . .. . . .... ... . . ... . .. ... . ... . . . 43 Data Processing .. . ... . . .. . . . .. ... .. ..... .... .. . .... ... . . . . .. ,. ............. . 44

IV RES ULTS AND DISCUSSIONS . ... . . ..... ...... . ........................ . 46 Soil -incubation Experiment..... ... . . . . ... .. .. .. . ... .. .. ... ...... .. ... ..... . . . . 46

Fertil iser Decomposition ...... . ..... ..... ..... . . . . .. . . . ... . . .. . . ... . . . . . 46 Acidity of Fertil iser-incubated soil .. . .. . ... .... .... . . .. . .. . ... .. . .. 49 Nitrogen Release of Fertil isers . . .... ..... .. . . . ...................... 51 Extractable P hosphorus in Fertil ise r�incubated Soil . .. .... 56 Exchangeable K, Ca and Mg in Fertil iser-incubated Soil 59 Correlation between Decomposition and Nutrient Release of Fertil isers . .. .... ... .. .... . ........ .. .. ... ... . . . . . ............. 64

Glass-house Experiment . . . . .. . . . ... . . . . ... . . . .. ...... .... ... . . . . .. .............. 66 Growth Rate of Rubber Seedl ings ... .... ... . ..... . ...... . ... .. . ... 66

Diameter ... .... ... .. ... .... .. .. .. .. .. .. . . .. . . . .. .. . .. . . . . ... ... ... . . . 67 Height ................ . .. ............... .... . .. .. . . . . ... ................ 69

Dry Weights . .. . . . ...... . . . ... .... .. ... ... .. .... . . . . . ............... 71 Residual Effect of Fertilisers in Soil . . . .. . . .... ... .. ......... ... .. 74 Nutrient Content in Plant Tissue . .. . . . ... ... .. .... .... .... .......... 76 Total Nutrient Uptake by Rubber Seedlings .. .. . . ... .. .. .. . . . 81 Nitrogen Uptake from SRF by Rubber Seedl ings . . . ....... 86 Correlation between Growth and Plant Analyses of Rubber Seedl ings ... . . .... ....... . ... ... .. . ......................... 95

v S UMMARY AND CONCLUSION .. . . .. . . . .. .. ... ....................... 100

BIBLIOGRAPHY ..... . ..... . . .. ... ... .. . . . . . . .. .... .. . . . ... . .. ... .... .... . .. . . . . . ... . . ... . . . . . . . .. . , 108

APPENDICES .. . . . .. . . . . . . . ... .. . . ... ..... . . ......... .. .......... . . . .. .. . ... . ........................ .. 129 A Original Data in the Soil-incubation Experiment . .. . . .. . .. .. ... . . .. . 130 B Analysis of Variance in t he Soil-incubation Experiment. . .. ... .. 138 C Original Data in the Glass-house Experiment.. ..... ... .......... ..... 145 D Analysis of Variance in the Glass-house Experiment .. .. . . .. . . . . . 180

VITA ... . . . . .... .. . . . ........................ ........................................ ............. ..... . . . . . . 205

v

LIST OF TABLES

Table Page

1 Some Characteristics of Soils Used in the Two Experiments ... ... 24

2 Specifications of Fertilisers Used in the Two Experiments............ 25

3 Fertiliser Doses Applied in the Two Experiments .... .... ........ ......... 26

4 Treatments of the Soil-incubation Experiment .......... ......... ........... 28

5 Structure of Analysis of Variance in the Soil-incubation Experiment.................................................. . . . ................................ 34

6 Treatments of the Glass-house Experiment .. .......... ............. .......... 35

7 Average Amount of Water Used for Watering Seedlings in the Glass-house Experiment . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . .. . .. . . . . . . . . .. . .. . . . .. . 38

8 Structure of Analysis of Variance in the Glass-house Experiment 45

9 Decomposition of Fertilisers Incubated in Soil ......... ..................... 47

10 Acidity of Fertiliser-incubated Soil .... .... . . .. ....... ...... .......... ............. 50

11 Release of Nitrogen in Fertiliser-incubated Soil ....... ......... . . . . . . '" 52

12 Extractable P in Fertiliser-incubated Soil ............... ....................... 57

13 Accwnulation of Extractable P and Its Relative Release Rate ...... 59

14 Exchangeable K, Ca and Mg in Fertiliser-incubated Soil .............. 60

15 Accwnulation of Exchangeable K and Its Relative Release Rate.. 62

16 Correlation between Fertiliser Decomposition and Fertiliser-nutrient Accwnulation in Soil ........................................ 65

17 Stem Diameter of Rubber Seedling ....................... .. . .................... 68

VI

18 Height of Rubber Seedling ......................................... ................... 7 0

19 Dry Weights of Different Plant Parts of Rubber Seedling ............. 7 2

20 Chemical Property of Initial and Final Soils in the Glass-house Experiment..................................................................... ............... 7 4

21a Nutrient Content of Rubber Seedling at 60 DAP .......................... 7 7

2Ib Nutrient Content of Rubber Seedling at 120 DAP ........................ 7 8

21c Nutrient Content of Rubber Seedling at 18 0 DAP ........................ 7 9

22a Total Nutrient Uptake by Rubber Seedlings at 60 DAP ................ 82

22b Total Nutrient Uptake by Rubber Seedlings at 120 DAP .............. 83

22c Total Nutrient Uptake by Rubber Seedlings at 18 0 DAP .............. 8 5

23a Results from l� Isotope Study on Rubber Seedlings at 60 DAP.. 8 8

23b Results from l� Isotope Study on Rubber Seedlings at 120 DAP 8 9

23c Results from l� Isotope Study on Rubber Seedlings at 180 DAP 9 0

24 Correlation between Growth and Plant Analysis of Rubber Seedling.......................................................................... . . . .......... 9 7

25 Correlation between Growth and Nutrient Uptake of Rubber Seedling.............................................................................. . . . ...... 9 9

26 Initial Fertiliser Analyses ............................................................. 131

27 Fertiliser Decomposition ........................... ............ ........ ...... ........ 132

28a Soil Analyses at 15 DAI .............................................................. 133

28b Soil Analyses at 30 DAI .............................................................. 134

28c Soil Analyses at 60 DAI ................................ ............. ................. 135

28d Soil Analyses at 120 DAI ............................................................ 136

28e Soil Analyses at 180 DAI ............................................................ 137

vii

29 ANOVA of Fertiliser Decomposition ... .. . . . .. ... . ... ...... .. . . .. .. . . . . . . . . . . . 139

30a ANOV A of Soil Analyses at 1 5 DAI .. . ............... ........ .......... ....... 140

30b ANOV A of Soil Analyses at 30 DAI . ............. ....... .... ...... ..... ....... 141

30c ANOVA of Soil Analyses at 60 DAI .. ... ...... . .... .. . ... ..... ............... . 142

30d ANOVA of Soil Analyses at 120 DAI . ....... . ........ . . ..... . .. ..... ........ . 143

30e ANOVA of Soil Analyses at 180 DAI ........ ............ ...... ............... 144

31 Chemical Analyses of Rubber Seed . ... . . . .. .. . . . . . . . . . . .. . ... . . . .. . ... . . ... . . . 146

32 Diameter Records on Rubber Seedlings .. ..... ..... . .. .... ....... . . . .. ...... . . 147

33 Height Records on Rubber Seedlings .. . ..... . . . . . . .. .. .... . . .. .. . . .. . .. . . . .. . .. 148

34 Dry-weight Records on Rubber Seedlings .. . . .... . . . . . . . . . .... . ... . . .. . . . .. . . 149

35 Chemical Analyses of Final Soil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . .. . . . . . . . . . . . 1 50

36a Chemical Analyses of Rubber Seedling at 60 DAP . . . ... . . . . . . . . . . . . . . . 1 5 1

36b Chemical Analyses of Rubber Seedling at 120 DAP . . . . . . . . .. . . . . . . . . . 1 53

36c Chemical Analyses of Rubber Seedling at 180 DAP . . . . . . . . . . . . . . . . . . . 1 55

37a Total Nutrient Uptake at 60 DAP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 57

3Th Total Nutrient Uptake at 120 DAP . . ... .... . . . . . . . . . . . . . . .. . . . . . . . . . .. . .. . . . . .. . 160

37c Total Nutrient Uptake at 180 DAP ...... .. .. ..... ... ... . .. .. . . . . . ... .. ... . .. . . ... 163

38 l� Analysis Data of Rubber Seedling .. ....... ... . .. . . .. ... . .. .... .. .... .. . ... 166

39a l� Analysis-based Calculations at 60 DAP .. . .. . . . . . . . . .. ... . ... . .. . . ..... 168

39b l� Analysis-based Calculations at 1 20 DAP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 72

39c l� Analysis-based Calculations at 180 DAP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176

40 ANOVA of Diameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 8 1

YIll

41 ANOVA of Height . . . . . . ....... . . . . . . . . .... . . . . . . . . . . . . ....... . . . . . .. . .. . . . . . . . . . . . . . . ... 183

42 ANOVA ofDryWeight ............................... ................................ 185

43a ANOVA of Plant Tissue Analyses at 60 DAP .............................. 187

43b ANOVA of Plant Tissue Analyses at 120 DAP............................. 189

43e ANOVA of Plant Tissue Analyses at 180 DAP ............................ 191

44a ANOVA of Total Nutrient Uptake at 60 DAP ............................. 193

44b ANOVA of Total Nutrient Uptake at 120 DAP ........................... 195

44e ANOVA of Total Nutrient Uptake at 180 DAP ........................... 197

45a ANOV A of Data from l� Isotope Study at 60 DAP ................... 199

45b ANOVA of Data from l� Isotope Study at 120 DAP ................. 201

45e ANOV A of Data from l� Isotope Study at 180 DAP . . . . . . . . . .. . .. 203

IX

LIST OF FIGURES

Figure Page

1 The Lay-out Plan of Glass-house Experiment ....... . . .. .... .... . . ... ... . . . 36

2 Percentage Nitrogen Release in Fertiliser-incubated Soil... . .. ... 5 5

3 Accwnulation of Fertiliser N in Rubber Seedlings . . . .. . . . . .. . .. ..... . ... 94

x

LIST OF ABBREVIATIONS

a.e. Atom excess

AB Agroblen

ANOVA Analysis of variance

BT Best Tab

CON Control treatment

DAI Day after incubation

DAP Day after planting

DF Degree of freedom

F F distribution

FNY Fertiliser nitrogen yield

FUE Fertiliser utilisation efficiency

KN Kokei Nugget

LAS Labelled ammonium sulphate

MS Mean of squares

NA Nurseryace

Ndff Nitrogen derived from fertiliser

NY Nitrophoska Yellow

RRIM Rubber Research Institute of Malaysia

RRIV Rubber Research Institute of Vietnam

SRF Slow-release fertiliser

SS Sum of squares

UPM Universiti Putra Malaysia

Xl

Abstract of the Thesis Presented to the Senate ofUniversiti P utra Malaysia in Fulfilment of the Requirements for the Degree of

Master of Agricultural Science

INFLUENCE OF SLOW-RELEASE FERTILISERS ON GROWTH OF RUBBER (Hevea Brasiliensis) SEEDLINGS

Chairman : Faculty:

By

TONG VIET THINH

June, 1997

P rof Dr. S harifuddin Haji Abdul Hamid Agriculture

Rubber, Hevea brasiliensis, is a valuable crop of some countries in

Asia. In the rubber industry, fertiliser application is one of the most e ffective

methods to e nhance growth of rubber see dlings in the nursery. However,

application of chem ical fertilisers has several disadvantages such as fast

nutrient leaching, fertiliser bum and requirement of intensive labour for split

applications. In recent years, slow-release fertilisers have been introduced to

solve the above problems o n many crops including rubber. S tudies on the

effect of slo w-release fertilisers on rubber are limited and there has been no

work reported on the use of isotope technique to accurately study n utrient

uptake and efficiency of fertilisers use.

Xll

This study was set up with the aim of studying the rate of nutrient

release of slow-release fertilisers and their effect on the performance of rubber

seedlings using l� isotope dilution technique. Two experiments, namely,

laboratory incubation and glass-house experiments were conducted. Five

fertilisers were evaluated, four of which were slow-release fertilisers

(Agroblen, Best Tab, Kokei Nugget and Nurseryace) and one conventional

chemical fertiliser (Nitrophoska Yellow). In the soil-incubation experiment,

Bungor and Sungai Buloh series soils were used, while in the glass-house

experiment, only Bungor series soil was used

Results from the incubation experiment showed that during the period

of incubation, Nitrophoska Yellow gave the fastest rate of fertiliser

decomposition and NPK release, while Nurseryace were persistently the

lowest. Higher fertiliser decomposition and release of N and K were obtained

in Bungor series soil as compared to Sungai Buloh series soil. However

phosphorus release in Bungor series soil was lower than that in Sungai Buloh

series soil. It was found that there was a very close relationship between

fertiliser decomposition and NPK release of slow-release fertilisers,

particularly for Kokei Nugget and Nitrophoska Yellow.

In the glass-house experiment, evaluation at 1 80 days after planting

showed that among the four slow-release fertilisers applied, Best Tab gave the

Xlll

highest growth and also gave the highest nitrogen uptake, total uptake ofN, P,

K, Ca and Mg, and fertiliser utilisation efficiency. Meanwhile, Nitrophoska

Yellow gave the lowest values of fertiliser nitrogen yield, fertiliser utilisation

efficency as well as total nutrient uptake.

The results obtained from the two experiments showed that Best Tab

slow-release fertiliser is the best fertiliser as compared to the other slow­

release fertilisers tested under the conditions of the study.

XlV

Abstrak Tesis yang Dikemukakan Kepada Senat Universiti Putra Malaysia Sebagai Memenuhi Syarat Keperluan Untuk Ijazah Master Sains Pertanian

PENGARUH BAJA LEPASAN PERLAHAN TERHADAP PERTUMBUHAN ANAK BENIH POKOK GETAH

Oleh

TONG VIET TRINH

Jun, 1997

Pengerusi: Prof Dr. S harifuddin Haji Abdul Hamid Pertanian Fakulti:

Pokok getah, Hevea brasiliensis, adalah tanaman bemilai di beberapa

negara Asia. Dalam industri getah, pembajaan adalah kaedah yang berkesan

untuk meningkatkan pertumbuha� anak benih getah di tapak semaian. Walau

bagaimanapan penggunaan baja kimia mempunyai beberapa masalah saperti

larutlesap nutrien yang cepat , pemeruapan baja, keperluan membaja dengan

kerap dan keperluan buruh yang tinggi. Kebelakangan ini, baja lepasan

perlahan tel ah diperkenalkan bagi menyelesaikan masal ah yang dinyatakan di

atas bagi kebanyakan jews tanaman termasuk getah. Kajian kesan baja lepasan

perlahan ke atas getah adal ah terhad dan sehingga keni, laporan mengenai

penggunaan teknik isotop bagi mengkaji pengam bilan nutrien dan

keberkesanan baja oleh getah juga ti dak di depati.

xv

Kajian ini adalah dijalankan untuk mengkaji kadar lepasan baja lepasan

perlahan, dan pengambilan nitrogen untuk perkembangan anak benih getah

dengan menggunakan teknik pencairan isotop l�. Kajian ini melibatkan dua

eksperimen, iaitu eksperimen pengeraman dan eksperimen rumah kaca. Lima

jenis baja telah dinilai, empat daripadanya adalah baja Iepasan perlahan

(Agroblen, Best Tab, Kokei Nugget dan Nurseryace) dan satu baja kimia biasa

iaitu Nitrophoska Kuning. Dalam eksperimen pengeraman, tanah siri Bungor

dan sm Sungai Buloh telah digunakan manakala dalam eksperimen rumah

kaca. hanya tanah siri Bungor digunakan.

Keputusan yang diperolehi daripada eksperimen pengeraman telah

menunjukkan baja Nitrophoska Kuning menghasilkan kadar penguraian baja

dan pelepasan NPK yang paling cepat. Sementara itu. Nurseryace merupakan

yang paling lambat. Di antara kedua jenis tanah, siri Bungor telah

mempamirkan penguraian baja dan pembebasan N dan K yang lebih cepat

berbanding dengan tanah siri Sungai Buloh, manakala pembebasan P pula

adalah lebih tinggi bagi tanah siri Sungai Buloh berbanding dengan tanah siri

Bungor. Terdapat perhubungan yang baik di antara penguraian baja dan

pembebasan NPK terutamanya oleh Kokei Nugget dan Nitrophoska Kuning.

Dalam ekperimen rumah kaca, penilaian pada hari ke 180 selepas

penananam telah mendapati bahawa Best Tab memberikan pertumbuhan yang

XVI

paling tinggi dan menghasilkan pengambilan nitrogen, jumlah pengambilan N,

P, K, Ca dan Mg, dan keberkesanan penggunaan baja yang paling tinggi.

Dalam pada itu, pengambilan nitrogen dan keberkesanan pembajaan bagi

Nitrophoska Kuning adalah yang paling rendah.

Berdasarkan keputusan dari kedua-dua ekperimen, didapati bahawa

Best Tab merupakan baja lepasan perlahan yang paling baik berbanding

dengan lain-lain baja lepasan perlahan yang dikaji.

XVII

CHAPTER I

INTRODUCTION

Slow-release or controlled-release fertiliser (SRF) is a special chemical

compound fertiliser that releases its nutrients slowly and safely for plants. So

far, only some countries have manufactured slow-release fertilisers, such as,

Japan, United States of America, Netherlands and Switzerland. In slow-release

fertiliser applications, generally, the amount of nutrient required for plant is

bulk-applied to soil at only one application per year. The slow-release fertiliser

can maintain its nutrients and functions in soil from a few months up to a few

years depending on the manufacturing process of manufacturers. It has been

reported that, though slow-release fertilisers were applied with a single

application, they gave minimum nutrient leaching, no fertiliser burn,

satisfactory nutrient supply and high performance on growth of plants. Because

of these advantages, slow-release fertilisers have been and will hopefully

become a promising new generation of fertiliser for use in various crops.

I

2

In rubber (Hevea brasllzensls) cultIVatIOn It IS well known that the

quabty of seedlIngs or stocks m the nursery Will determme the crop

performance m the field, and that fertIhser applIcatIon IS one of the most

effective methods to enhance growth of rubber seedbngs. Currently, chemical

fertilisers are used in the rubber nursery whIch may result m fertIliser burn of

roots, rapid nutrient leaching In soIl, as well as hIgher labour demand for split

applications.

In VIew of its controlled nutrIent release properties, slow-release

fertilisers are greatly expected to overcome the problems Imposed by

conventional fertilisers. In recent years, many dIfferent kinds of slow-release

fertilisers have been made avaIlable m the market, and each of them was

recommended for certam crops. Nevertheless, actual effiCIency of slow-release

fertilisers on growth of crops, mcludmg rubber seedlmgs, have not been shown

to be satisfactory. In other words, m order to identIfY proper kmds of slow­

release fertilIser for rubber seedlmgs, mtensive studIes m thIs area IS reqUIred.

At present, in Asian countrIes, slow-release fertIlisers are neither

popular nor widely used due to theIr hIgh cost, and therefore, there have been

few slow-release fertiliser trIals BeSIdes, on a global scale, to date only a few

slow-release fertIlIser studIes have been done on rubber trees, and there was

absolutely no slow-release fertIlIser mvestIgatIon WhICh employed ISOtOpe

techruque to study nutrient uptake and fertIhser effiCIency Due to thIS and on

3

the basis of some slow-release fertilisers available for nursery plants, this

project was conducted using I� isotope dilution technique to

1) study the release rate of slow-release fertilisers on two types of

Malaysian soils,

2) determine the efficiency of nutrient uptake from slow-release

fertilisers by rubber seedlings, and

3) evaluate the influence of slow-release fertilisers on the performance

of rubber seedlings.

CHAPTER II

REVIEW OF LITERATURE

Due to the shortcomings of normal chemical fertilisers, such as,

fertiliser burn, fast leaching, and surface runoff, extensive efforts have been

undertaken to search for a new type of fertiliser that can overcome these

disadvantages. Since the 1960s the United States, Japan and some European

countries have taken the lead in manufacturing such new fertilisers. They are

chemically compound fertilisers and usually called slow-release fertilisers or

controlled-release fertilisers. Thus far, many of SRF have been manufactured

and tested on various crops.

Classification of Slow-release Fertilisers

For slow-release fertilisers, efforts to achieve controlled availability of

applied nutrients has been centred in two major areas. One was through

controlled release either by using slowly soluble compounds or by coating

soluble compounds with an insoluble or inert material. Coated materials will

gradually be decomposed followed by slow nutrient release. A second area was

4

5

through protected availability. This was designed to keep the nutrients in a

form that is readily available to crops but partially protected from

immobilisation or nitrification in the soil system, especially in anaerobic

condition. Nitrification inhibitors are included in this area (Stangel, 1970).

The term 'controlled-release fertiliser' or 'slow-release fertiliser' refers

to a fertiliser that for any reason releases its nutrient contents over an extended

period or releases plant nutrients slowly throughout a growing season or even

several continuous growing seasons (Hignett, 1974). In other words, slow­

release fertilisers are the ones that release their plant nutrients at a rate which

possibly permits maximum plant uptake and reduces minimally nutrient loss

due to leaching and surface runoff (Tajuddin, 1979).

Slow-release fertilisers contain one or more of the popular plant

nutrients, such as N, P, K and sometimes some additional micro-nutrient

elements. However, in practice, the need for a slow-release nitrogen fertiliser is

more acute than for phosphate, potash or micro nutrient elements (Hignett,

1974). Hence, the manifold of slow-release fertilisers mainly comes from

nitrogen fertilisers . Three main groups of slow-release fertilisers are slowly

soluble fertilisers, coated fertilisers, and nitrification inhibitor-mixed

fertilisers.

6

Slowly Soluble Fertilisers

Slowly soluble fertIhsers are chemIcal compounds that are only slightly

soluble m water and usually made by reacting water-soluble fertilisers with

inert materials (Ta]uddin, 1979). Most slowly soluble fertilisers are related to

urea. For this kind of slow-release fertiliser, urea component is often included,

for example, Best Tab, CDU (cyclodiurea), FU (2 furfurilidene 3 urea),

Glycoluril, IBDU (isobutyliden diurea), Nurseryace, Urea-Z (mixtures of

ethylene ureas), Ureform (urea-formaldehyde).

The general process of makmg slowly soluble fertilisers were reported

as follows: i) Water-soluble mtrogen sources are reacted chemically with an

inert chemical at a reqUIred rallo and temperature; il) After that, before cooling

and solIdIfymg, the mIxture IS dIVIded mto deslfed particles m a granule­

maker; in) WIth dIfferent mert chemIcals, ratios and particle sizes, different

types and characters of slowly soluble fertlhsers are manufactured (Abad et al.,

1989; Guyot et al., 1990; RIemenschneider, 1984)

Coated Fertilisers

So far, coated fertIlIsers have been popular WIth the well-known brands

avaIlable m the market, such as Agrlform, Agroblen, Basacote, Ficote, Gold-N

7

(sulphur-coated urea), Lewatlt, Nutricote, Osmafonn, Osmocote, PI antacote ,

Plantosan, Vitamon. A wide range of materials and techmques have been

explored to produce more and more effective controlled-release fertilIsers.

Numerous covering materials were used for such slow-release fertilisers, for

instance, plastic films, resins, waxes and other barriers. The most popular

coating material was a copolymer of dicyclopentadien and glycerol ester. This

material allows for a fertiliser-nutrient release based on osmotic exchange as

the material comes in contact with soil water. Coated granular fertilisers were

manufactured by Archer Daniels Midland company (ADM Co.) under the trade

name Osmocote from 1964, and since 1974 they have been manufactured and

marketed by Sierra Chemical Company under exclusive licensmg from ADM

Company. Osmocote was recommended for nursery stocks, turf, flonculture

and high-value row crops (powell, 1968).

According to Mahara et al. (1992), coated granular fertIlIsers

essentially consist of fertiliser granules that are selected from urea, ammomum

sulphate, ammonium chloride, ammonium nitrate, potaSSIUm chlonde,

potassium sulphate, potassium nitrate, sodium nitrate, ammonium phosphate,

potassium phosphate or calcium phosphate, which are covered on the outside

with a copolymer coat in 5-40% (w/w) ratio. The copolymer compnses unItS of

vinyl chloride and ethylene in a proportion of 50:50 - 90: 1 0 by weIght

Sulphur-coated urea (SCU) is another controlled-release fertIlIser that

has been developed by Tennessee Valley Authority (TV A) smce the 1960s