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Soil health and Nutrient Management . P. D. Sharma Assistant Director General (NRM) ICAR, Krishi Anusandhan Bhavan II New Delhi-110 012. Soil Health.
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Soil health and Nutrient Management P. D. Sharma Assistant Director General (NRM) ICAR, Krishi Anusandhan Bhavan II New Delhi-110 012
Soil Health • Capacity of a soil to function within ecosystem boundaries to sustain biological productivity, maintain environmental quality and promote plant and animal health. • In the context of agriculture, it may refer to its ability to sustain productivity. • A healthy soil would ensure proper retention and release of water and nutrients, promote and sustain root growth, maintain soil biotic habitat, respond to management and resist degradation
Measure of Soil Health • Governed by a number of physical, chemical and biological attributes and processes. • Expressed by different quantitative and qualitative measures of these attributes as also by outcomes that are governed by the soil such as productivity, nutrient and water use efficiencies and quality of produce.
Declining Soil Health – A Cause of Concern • Deceleration in growth of total factor productivity in agriculture, especially in IGP states. Source : Kumar et al. (2004)
Declining Soil Health – A Cause of Concern Falling productivity growth rate (% per annum) of major crops in India
Food grain production and fertilizer use Fertilizers – An important input contributing 50% towards improvement in crop productivity
Declining Fertilizer Response Low Fertilizer Response - Irrigated Areas
Declining Nutrient Response Fertilizer Nutrient Response - Irrigated Areas
Nutrient Status – N P K Indian soils poor in N and P with 89 and 80 percent soil samples in low to medium category; relatively better in K with 50 percent samples only low to medium.
Nutrient Status –Micro and Secondary S, Zn, B, Mo, Fe, Mn and Cu deficient to the tune of 41, 49, 33, 22, 12, 5 and 4 % respectively.
Sulphur Deficiency in Indian Soils • The deficiencies are widespread covering 40- 45% • districts and 60mha of net sown area; occurrence • more in the southern region. • The deficit to the tune of 1mt/annum.
Imbalanced fertilizer use evidenced by wider fertilizer consumption ratios
Nutrient Mining in Soils of India (mt) • Increased mining of soil potassium a cause of more • rampant decline in rice yields compared to wheat in IGP • (data from 24 research stations) • Source : Tandon (2004)
Projected Food Grain Production, Fertilizer Demand, likely Consumption and Gap
Declining Soil Health – A Cause of Concern • Managing soil health a formidable challenge to ensure productivity, profitability and national food security. • The United Nations Millennium Development Task Force on hunger made Soil Health Enhancement as one of the five recommendations for increasing agricultural productivity and fight hunger in India.
Integrated Nutrient Management (INM) – Panacea for soil health and productivity INM envisaging conjunctive use of chemical fertilizers, organic manures and biofertilizers enhances nutrient use efficiency, soil health, crop yields and profitability Need to augment supplies of organic manures, fortified, coated & customized fertilizers supplying secondary and micronutrients, biofertilizers and soil amendments to have INM on a sound footing. Site specific nutrient management.
Site Specific Nutrient Management Rice-Wheat Cropping System Contd..
Site Specific Nutrient Management Rice-Wheat Cropping System
Enhancing availability of organic manures • Recycling and composting/ vermi composting of urban, animal and agro industrial waste • About 57MT of urban solid waste generated per annum with potential to supply 8MT of good quality compost. • Present availability 383 mt against the moderate requirement of 900 mt / annum (@5 t / ha on gross cropped area of 185 mha).
Promoting bio-fertilizers Production (thousand tonnes) • 164 units producing only one-third of installed capacity of 67,000 t/annum • The consumption is skewed - 90% in south & west zones of the country Production zone wise (%)
Acid Soils • About 12 m ha of arable acid soils with pH<5.5 have low nutrient use efficiency and crop productivity. • Liming to enhance nutrient use efficiency and productivity of crops, especially of pulses and oilseeds. • The practice saves 50% fertilizers
Salt Affected Soils Reclamation of 7m ha of salt affected soils for increased nutrient use efficiency and productivity
Utilization of Indigenously Available Nutrient Sources • Large reserves of low grade rock phosphate(160MT) and K bearing mica in the country could be co-composted for production of P & K enriched manure • Phospogypsum, a by-product of fertilizer industry containing 16% S and 21%Ca, a potential source of S and Ca for crops. • About 7MT of phosphogypsum generated per annum has a potential to supply 1 mt of S and 1.4 mt of Ca • Coarse textured acidic and sodic soils low in S and Ca to benefit from its supplementation.
Fertilizers Policy Measures • Nutrient Based Pricing and Subsidy :The pricing of fertilizers and subsidy on them to be fixed as per nutrient content and not product wise. • The move to encourage use of complexes and broaden the basket of fertilizers for balanced fertilizer use • The new pricing mechanism would reduce dependence on DAP. • The SSP containing 11% sulphur to be promoted to correct wide spread sulphur deficiency in soils besides a P source.
Promoting Fortified and Coated Fertilizers • The fertilizers to be fortified and coated with micro and secondary nutrients to correct their deficiencies in soils – Zincated urea, boronated SSP & DAP etc. • Policy decision by the Govt. to allow additional cost of fortification and coating to manufacturers (5-10% above MRP)
Promoting Fertigation and Water Soluble / Speciality Fertilizers • Fertigation increasing nutrient use efficiency by 40% to be popularized for fruits, vegetables, flowers and plantation crops. • Hold great promise as micro-irrigation to be expanded on 69 m ha in subsequent plan periods • The fully water soluble fertilizers are costly due to heavy custom duty & sales tax besides higher initial cost. • Need to be manufactured in India and brought under FCO 1985.
Strengthening Soil Testing Service • The service presently inadequate with a capacity to analyze only 7m soil samples/ annum against 120 m farm holdings in the country. • Need to open more soil testing laboratories at least one each in different districts with state of art facilities. • The laboratories to participate in the preparation of geo-referenced soil fertility maps at district and block levels. • National Commission on Farmers has recommended additional 1000 advanced soil testing laboratories in the country.
Organic Carbon Status • Soil organic carbon (SOC) governs soil productivity and environment. • The earlier studies linked reduced productivity of the rice-wheat system in IGP plain with declining soil organic matter (SOM) content. • The recent studies on SOC build up in soils over a long period subscribe to a different school of thought. • The evaluation of large soil test data for 25 years (1981-82 to 2005-06) has revealed improvement in SOC status by 38 % under intensive agriculture in Punjab.
Conclusion • Widespread nutrient deficiencies and deteriorating soil health are cause of low nutrient use efficiency, productivity & profitability. • Adoption of site-specific balanced and integrated nutrient management involving major, secondary and micro nutrients, organic manures, biofertilizers and amendments. • Conducive policy environment for more investments in the fertilizer sector for sustained supplies of fertilizers. • Utilizing all indigenously available nutrient sources to reduce dependence on imports. • Developing new efficient fertilizer products/ approaches through state of art R & D applications. • Effective soil testing service to back up precise fertilizer use. • Creating awareness amongst farmers on benefits of balanced fertilization.
