Publications

By Manoj Kumar Sharma and Prakash Kumar

Phosphorus deficiency is widespread in Indian soils and response of cereals to applied P is often spectacular. P use has increased significantly with increasing food grain production in India. Recent increase in P fertilizer cost, however, has raised concerns about the profitability of P application in cereals. Economic assessment based on application rates, nutrient response, cost of phosphate and minimum support price of the cereals showed substantial return on investment.

Nitrogen (N) is a key factor for cereal production in India. N is predominantly supplied to the plants through fertiliser application. The average response to applied fertiliser N has been declining steadily over the past decades. As a result, farmers are compelled to apply higher doses of fertiliser N to maintain the yields of the preceding years.

Potassium (K) fertilizer cost has increased considerably over the past three years. The sharp increase in price has raised doubts about the profitability of potassium application in cereals where the Minimum Support Prices (MSP) is low. On-farm K response studies in rice, wheat and maize, spread across the Indo-Gangetic Plains, highlighted that grain yield response to fertilizer K is highly variable and is influenced by soil, crop and management factors.

The greatest challenge facing mankind in the coming decades is to produce the basic necessities of food, feed, fuel and raw materials from limited land area. Increasing food demand from limited land resources in the coming decades would require increased use of fertilisers. This will require application of proven scientific principles of nutrient management that ensures improved productivity of crops per unit area without adding to environmental concerns.

Maize is an important crop for food and nutritional security in India. Strong market demand and resilience of maize to abiotic and biotic stresses have increased the area and production of maize in the country over the past decade. Productivity of maize, however, has not increased proportionately and significant yield gaps are evident across maize growing areas in the country.

A large part of precision agriculture research in the developing countries is devoted towards precision nutrient management aspects. This has led to better economics and efficiency of nutrient use with off-farm advantages of environmental security. The keystone of precision nutrient management is analysis and interpretation of spatial variability of soils by establishing management zones.

Potassium input-output balances in different states of India were estimated and mapped using the IPNI NuGIS approach. Results showed negative K balances in most of the states suggesting deficit K application as compared to crop K uptake.

Will the improvements of food production be able to match population growth?

The necessity of increasing food production to meet the demand of the ever-increasing population in India hardly requires any over-emphasis. Estimates suggest that at the current level of production (263 million tonne, Mt), an additional 5 Mt food grain has to be added each year to the national food basket for the next decade or so to feed the increasing population.

Nutrient Source Specifics are one-page fact sheets highlighting various fertilizers and nutrient sources. Written by IPNI scientific staff, these items are primarily for educational use by a non-technical audience.

Rice (Oryza sativa L. )–wheat (Triticum aestivum L. ) cropping in South Asia is under stress due to widespread removal of plant nutrients in excess of their application. Potassium (K), sulfur (S), and Zinc (Zn) application to rice and wheat in 60 farmer’s fields in five districts across northern India showed that application of K increased rice yields by 0. 6 to 1. 2 Mg ha–1 and wheat yields by 0. 2 to 0. 7 Mg ha–1 across the locations varying in soil texture, soil K, climate, and irrigation.

Evidence from long-term fertilizer experiments in rice–rice (R-R) or rice–wheat (R-W) systems strongly indicates significant yield responses to K application and negative K balances where K application is either omitted or applied suboptimally. South Asian farmers neglect K application to crops and remove crop residues from fields. These practices may strongly affect yield and soil K-fertility status in the emerging rice–maize (R-M) systems in different locations of South Asia.

A review of the published literature showed variable K response in oilseeds and pulses across India. Economic calculations, using current prices of crop commodities and potash fertiliser, revealed significant return on investment to fertiliser K application in these crops.

Emerging data from on-farm and on-station experiments in the rice-maize systems in India and Bangladesh have revealed very high system productivity and high responses of maize and rice to applied K.

Proceedings of the IPI-OUAT-IPNI International Symposium. Bhubaneswar, Orissa, India, 5-7 November 2009. Volume I: Invited Papers This publication, which is a result of the IPI-OUAT-IPNI International Symposium on “Potassium Role and Benefits in Improving Nutrient Management for Food Production, Quality and Reduced Environmental Damages”, which took place on 5-7 November, 2009 in Bhubaneswar, Orissa, India, contains all voluntary papers that were presented in the Poster Sessions at the event.

On-farm experiments conducted at 60 locations in northern India demonstrated that yields and profits for rice and wheat increased significantly with a combined application of K, S and Zn along with farmer fertilisation practice that primarily focuses on N and P application. Application of Zn improved grain Zn contents in rice and wheat, which is critical for nutritional security in the region.

Potassium application led to increases in tuber yield, plant growth characteristics, tuber quality, K uptake and maintenance of available K in soil under cassava.

Recognizing the need for providing improved nutrient management guidelines to farmers growing transgenic cotton, IPNI Cooperators from southern region of South Asia published a paper that highlights the importance of using yield target-based approaches and suggests guidelines for right application rates of major, secondary, and micronutrients based on the principles of site-specific nutrient management.

On-farm and on-station trials showed that balanced fertilisation (i. e. , applying the right rates of N, P, K, S, Zn, B, and Ca) helped in maximising groundnut yield, nutrient uptake, and farmer profitability.

West Bengal soils, thought to be rich in K, showed a significant increase in grain yield of rice and wheat with K addition over the existing fertilisation practice.

Rice (Oryza sativa L. ) and maize (Zey mays) are grown in 3. 5 million hectares (Mha) in Asia that includes 1. 5 Mha in South Asia. Rice-maize systems are emerging all around South Asia but in particular are developing quite rapidly in Bangladesh and South and North India. These crops are grown in sequence on the same land in the same year either in double–or triple-crop systems to meet the rice demand of a rapidly expanding human population and maize demand of livestock and poultry.

Potassium concentrations in irrigation waters varied greatly across different locations in India (spatial), different times of the year (temporal), and different sources of irrigation used.