Current Advances in Agricultural Sciences 2(1): 10-12 (June 2010) ISSN 0975-2315

Trend of fertility status of Indian soilsH PATHAK

Division of Environmental Sciences, Indian Agricultural Research Institute, New Delhi 110 012Email: hpathak.iari@gmail.com

Received: April 2010

ABSTRACTThere is an increasing concern about the sustainability of Indian agriculture because of deterioration in soil fertility.The data from soil testing laboratories and published literature were analyzed to determine the trend in fertilitystatus of agricultural soils of India since 1967, when the Green Revolution set in. Based on the soil test values of N, Pand K, soil samples were classified into three categories i.e., low, medium and high, and nutrient index was calculatedfor soils of different states. In some states like for example, West Bengal, Gujarat, Tamil Nadu, N fertility increased,while it declined in Orissa and Kerala. In the remaining states the nitrogen fertility status remained almost samefrom 1967 to 1997. An increasing trend in P status of soil was observed in Assam, Karnataka and Kerala. In the rest ofthe states it remained unchanged. Potassium fertility either remained same or decreased. Available informationindicated that the soil organic carbon content either remained static or increased in certain regions of India. Therefore,contrary to the general perception, there has not been much depletion of soil fertility of agricultural soils of thecountry over the years. Detailed data on time series are required to ascertain the trend in fertility of Indian soil.

Key words: Fertility, Nitrogen, Phosphorus, Potassium, Soil organic carbon

Soil is the critical component of the earth system,functioning not only for the production of food, fodder andfiber but also in the maintenance of local, regional and globalenvironmental quality. Farmers in Asia, for centuries, havepracticed a cultural system that ensured modest but stableyields, yet maintained a desired level of fertility in soil. Thisequilibrium was disturbed by the need to increase productionthrough introduction of high yielding varieties, intensive useof chemical fertilizers and pesticides and extensive tillage. Thereare now concerns whether the dramatic increase in production,which followed the Green Revolution, is sustainable.

Importance of soil in supplying plant nutrients is knownsince the beginning of agriculture. The concept was moreconvincingly advocated since Liebig’s time around 1840, whenmany methods have been tried to get precise basis for estimatingsoil nutrient supplying capacity and predicting the fertilizerrequirements of crops. Agriculture in South Asia, until themiddle of the twentieth century, however, relied mostly oninherent nutrient reserve of the soil and organic manure. Frommid-sixties use of fertilizers is increasing steadily along withthe introduction and expansion of modern high yieldingvarieties accompanied by development of irrigation facilities inIndia. However, recent reports suggest a declining trend inproduction of rice and wheat in South Asia (Ladha et al., 2003).Major causes, which have been suggested, include gradualdecline in the supply of soil nutrients causing nutrient (macroand micro) imbalances due to inappropriate fertilizer applicationsand decline in soil organic matter content. With the decline inyield the partial factor productivity from applied nutrients isgoing down resulting in increasing costs of production. Thisat the same time has associated with environmental costs in

terms of nutrient losses in gaseous form and leaching. It istherefore essential that nutrient supplying capacity of soil becontinuously monitored to ensure and improve sustainabilityof agriculture. The objective of this paper was to analyze thetrend in fertility status of Indian soils since 1967, when theGreen Revolution was initiated.

MATERIALS AND METHODSThe soil test data are the best source available to assess

soil fertility status. Currently there are 533 static laboratorieswith at least one laboratory in each agriculturally importantdistrict and 108 mobile soil testing laboratories in the country.Each laboratory handles 2000 to 72,000 samples a year andprovides fertilizer recommendations. Based on the soil testvalues for different nutrients, soil samples are generallyclassified into three categories, low, medium and high (Table1). Using these fertility classes nutrient index was calculatedas per the following equation.

Nutrient index = (NL * 1 + NM * 2 + NH * 3) / NT

Where, NL, NM and NH are number of samples falling inlow, medium and high classes of nutrient status, respectivelyand NT is total number of samples analyzed for a given area.

Analysis of these data over a period of years will providethe changing pattern of soil fertility down the years. The soilfertility status data of various states of India, for 1967, 1977and 1997 was taken from Bajaj and Ramamoorthy (1969), Ghoshand Hassan (1980) and Motsara (2002), respectively. Soilnutrient index of different states was calculated for these 3years.

PATHAK – TREND OF FERTILITY STATUS OF INDIAN SOILS 11

RESULTS AND DISCUSSION

Nitrogen fertility statusThe soil N fertility status in majority of the states was

medium except in the North Eastern states, where the N statusin soil was high (Table 2). In West Bengal, the N fertility indexincreased from 1.47 in 1967 to 1.67 in 1997. Similar increasingtrend was observed for Gujarat (1.13 in 1967 to 1.71 in 1997),Tamil Nadu (1.1 in 1967 to 1.34 in 1997). But the N fertility indexdeclined in Orissa (1.92 to 1.57) and Kerala (from 2.11 to 1.66)during 1967 to 1997. In the remaining states the N fertility indexremained almost same during the period (Fig. 1). For the countryas a whole the N fertility index increased from 1.59 to 1.79 duringthe last four decades (1967 to 1997) (Table 2, Fig. 2).

Phosphorus fertility statusPhosphorus fertility status has been medium in majority

of the states. In Haryana a decreasing trend (2.00 in 1967 to 1.20in 1997) in the P fertility status was observed. It was oppositein case of Assam (1.00 to 2.13), Karnataka (1.06 to 1.90) andKerala (1.11 to 2.35). The rest of the states did not show anydistinct trend in the fertility status of phosphorus though therehave been fluctuations in the fertility status over the period(Fig. 1). For the whole country the phosphorus status changedfrom 1.50 to 1.46 during 1967 to 1997 (Table 2, Fig. 2).

Potassium fertility statusPotassium fertility was medium in most of the states. An

increase in potassium fertility status was observed in the statesof Orissa (1.46 to 1.93), Maharashtra (2.40 to 2.66) andKarnataka (2.00 to 2.54) during 1967 to 1997. A decreasing trendwas observed in Himachal Pradesh (2.00 to 1.63). In theremaining states there was fluctuation in the potassium fertilitystatus but no specific trend was observed (Fig. 1). In most ofthe states the potassium fertility increased in 1977 from the1967 level. But in 1997 the potassium fertility status eitherremained same or decreased marginally from 1977 level. On allIndia basis the potassium fertility increased from 2.00 in 1967to 2.17 in 1997 (Table 2, Fig. 2).

Simultaneously, due importance needs to be given toorganic carbon too, which also determines the soil fertility.Ladha (2003) reported that the status of soil organic carbonremained static for the last 25-30 years based on the results oflong-term fertility experiments on rice-wheat cropping systemsin northwest India.. Bhattacharya et al. (2007), however,reported an increase in SOC stock in the last 25 years between1980 and 2005 in the Indo-Gangetic Plains and the black soilregion in the semi-arid tropics. They suggested that theagricultural management practices advocated through theNational Agricultural Research Systems of India for the last 25years helped in maintaining the SOC in major crop growingzones of the country. Recently Pathak et al. (2010) estimatednutrient budget of Indian agriculture and showed that therewere positive balances of N (1.4 Mt) and P (1.0 Mt) and anegative balance of K (3.3 Mt). Krishna Prasad et al. (2004),Krishna Prasad and Badarinath (2006) and Murugan andDhadwal (2007) also estimated net accumulation of N in soil(positive N balance) ranging from 1.9 to 14.4 Mt. However,

0.0

0.5

1.0

1.5

2.0

2.5

N P K

Nutrient

Nut

rient

inde

x

1967 1977 1997

Fig. 2. Trend in nutrient index over the years in Indianagricultural soils

Table 1. Soil fertility ratings based on soil test values

Soil test Low Medium High Organic C (%) <0.5 0.5-0.75 >0.75 Olsen P (kg ha-1) <10 10-25 >25 Ammonium acetate extractable K (kg ha-1) <108 108-280 >280

Fig. 1. Change in nutrient index of agricultural soils of the country overthe years.

12 CURRENT ADVANCES IN AGRICULTURAL SCIENCES 2(1): JUNE 2010

these estimates, differed from that of Fertilizer Association ofIndia (FAI 2000), which projected a negative balance of N. Thisis because of exclusion of addition of N through irrigation, rainand crop residues in the study. Panda et al. (2007) observedpositive balances of N and P and negative balance of K in thelong-term experiments in rice-rice systems in the treatmentswith N and P application. From the above study it can be arguedthat there has not been much depletion of soil fertility over theyears in India.

ACKNOWLEDGEMENTThe author thanks Dr. A. Chatterjee and Dr. U.K. Singh,

Indian Agricultural Research Institute, New Delhi for their helpin collecting the data.

REFERENCESBajaj JC and Ramamurthy B, 1969. Available nitrogen, phosphorus

and potassium status of Indian soils. Fertiliser News 14: 25–28.Bhattacharyya T, Chandran P, Ray SK, Pal DK, Venugopalan MV,

Mandal C and Wani SP, 2007. Changes in levels of carbon insoils over years of two important food production zones ofIndia. Current Science 93:1854-1863.

FAI, 2000. Fertilizer Statistics. Fertilizer Association of India, NewDelhi.

Ghosh AB and Hasan R, 1980. Nitrogen fertility status of soils ofIndia. Fertiliser News 25(11): 19-24.

Krishna Prasad V and Badarinath KVS, 2006. Soil surface nitrogenlosses from agriculture in India: A regional inventory withinagroecological zones (2000–2001) International Journal ofSustainable Development 13: 173–182

Krishna Prasad V, Badarinath KVS, Yonemura S and Tsuruta H, 2004.Regional inventory of soil surface nitrogen balances in Indianagriculture (2000–2001). Journal of Environment Management73: 209–218.

Ladha JK, Dawe D, Pathak H, Padre AT, Yadav RL, Bijay-Singh,Yadvinder Singh, Singh Y, Singh P, Kundu AL, Sakal R, Ram N,Regmi AP, Gami SK, Bhandari AL, Amin R, Yadav CR,Bhattarai EM, Das S, Aggarwal HP, Gupta RK and Hobbs PR,2003. How extensive are yield declines in long-term rice-wheatexperiments in Asia? Field Crops Research 81: 159-180.

Motsara MR, 2002. Fertility status of Indian soils. Fertiliser News47(8): 15-22.

Murugan AV and Dadhwal VK, 2007. Indian agriculture and nitrogencycle. In Agricultural nitrogen use & its environmentalimplications (Eds Abrol YP, Raghuram N, Sachdev MS), IKInternational Publishing House Pvt. Ltd. New Delhi, 2007, pp.9-28

Panda D, Samantaray RN, Misra AK and Senapati HK, 2007. Nutrientbalance in rice. Indian Journal of Fertiliser 3: 33-38

Pathak H, Mohanty S, Jain N and Bhatia A, 2010. Nitrogen,phosphorus, and potassium budgets in Indian agriculture.Nutrient Cycling in Agroecosystems 86: 287-299.

Table 2. Nutrient index of agricultural soils in different states of the country over the years.

State Nitrogen Phosphorus Potassium

1967 1977 1997 1967 1977 1997 1967 1977 1997

Andhra Pradesh 1.55 1.38 1.55 1.50 1.19 1.57 2.30 2.54 2.52

Assam 2.00 2.00 1.76 1.00 2.11 2.13 1.33 2.20 2.14 Bihar 1.73 1.23 - 1.27 1.55 - 2.33 2.08 -

Gujarat 1.13 1.63 1.71 1.38 1.80 1.64 1.00 3.00 2.60 Haryana 1.00 1.00 1.04 2.00 1.83 1.20 2.00 2.80 2.05

Himachal Pradesh 2.00 2.25 2.34 2.00 2.00 1.93 2.00 1.95 1.63

Karnataka 2.33 1.53 2.05 1.06 1.23 1.90 2.00 2.21 2.54

Kerala 2.11 1.70 1.66 1.11 1.70 2.35 1.00 2.00 1.98

Madhya Pradesh 1.16 1.18 1.27 1.88 1.68 1.84 2.56 2.64 2.48 Maharashtra 1.57 1.36 1.40 1.38 1.40 1.16 2.40 2.52 2.66

Orissa 1.92 1.69 1.57 1.31 1.62 1.54 1.46 1.84 1.93

Punjab 1.89 1.00 1.67 2.33 1.68 1.93 2.00 2.42 2.40

Rajasthan 1.14 1.04 - 1.93 2.08 - 2.07 2.62 -

Tamil Nadu 1.10 1.08 1.34 1.60 1.40 2.11 2.00 2.54 2.40

Tripura 2.00 2.00 1.76 1.00 1.00 1.69 1.00 1.00 1.70

Uttar Pradesh 1.15 1.16 1.25 1.31 1.25 1.32 2.00 2.27 2.21 West Bengal 1.47 1.53 1.67 1.87 1.73 2.05 2.20 1.94 2.04

Country 1.59 1.47 1.67 1.50 1.41 1.46 2.00 2.07 2.17