International Potash Institute
K in the Literature

Improving and maintaining soil quality for enhancing and sustaining agricultural production is of utmost importance for India's food and nutritional security. Though India has made a record production of about 230 million tonnes of food grains in 2007-08, it will need to produce about 320 million tonnes of food grains by 2025 if the trend in rising population persists. This challenge can be met by greater and more efficient use of fertilisers and organic sources of plant nutrients. The results from several long-term fertiliser experiments conducted in different agro-ecological regions involving diversified cropping systems and soil types have shown that imbalance fertiliser use particularly N alone had a deleterious effect on soil productivity and health and the damaging effects in the absence of P and K fertilisers varied in the order. Alfisols>Vertisols>Inceptisols>Mollisols. In a period of less than ten years, crop productivity in N alone plots came to almost zero in Alfisols. Integrating organic manure (FYM @ 10-15 Mg ha^-1) with 100% recommended NPK fertiliser doses not only sustained high productivity but also maintained fertility in most of the intensive cropping systems and soil types. The results further revealed that soil type was one of the most important factor affecting fertiliser use efficiency and crop yields. Therefore, sustained efforts are needed to improve and maintain this most important natural resource base (soil) through judicious integration of fertilisers, organic and green manures, crop residues and biofertilisers so that it nourishes intensive cropping without being irreversibly damaged in the process. Important soil chemical parameters (soil organic matter, pH, electrical conductivity, available major and micronutrients), physical parameters (texture, depth of soil, infiltration, bulk density, water holding capacity), and biological parameters (microbial biomass, C and N, potentially mineralizable N, soil respiration, soil biodiversity) interact in a complex way to provide soil important functions thereby affecting nutrient use efficiency and crop productivity. The balanced fertilization along with manures improves the soil aggregation as well as biological activity of soil and maintains soil quality and sustainability of productivity. The soil quality index calculated for the different fertiliser treatments decreased in the following order: 0.838 (100% NPK + FYM) >0.777 (150% NPK) >0.729 (100% NPK) >0.637 (100% NP)/0.637 (50% NPK)/0.623 (reference) >0.591 (100% N) >0.552 (control).