Potassium mining in Indian agriculture: Input and output balance

Abstract

India registered an ever recorded food grain production of 230 mt with a consumption of 23 mt of NPK’s during 2007-08 and it was estimated that about 45 mt of nutrients are needed to produce 300 mt of food grains by 2025 to sustain the requirement of growing population. Present intensive production systems in India characterized by heavy removal and inadequate replenishment of nutrients resulted in multiple nutrient deficiencies and depletion of soil nutrient reserves. For sustaining the crop productivity and to restore the soil fertility, there is a need to arrest depletion of soil nutrient reserves for which understanding of crop nutrient balances is important. There were many attempts to examine the potassium mining at individual plot level, long term fertilizer experiments, state level and country level. In most of these reports, fertilizer inputs and crop removals were only considered, thus resulting in the large scale negative K balances in Indian agriculture. In agroecosystem, K is contributed by many sources like animal manure, crop residue, compost, rice burning residue, irrigation water and rain etc. Similarly, besides crop K removal, K is lost to deeper layers by rain or irrigation water by leaching. By considering all these inputs and outputs, the K balance in Indian agriculture is about 3 million tonn year. This total balance can be further refined by considering area under conservation agriculture, green leaf manuring like glyricidia and other non-conventional sources of potassium being used in Indian agriculture, which may further reduce the overall negative balance of K Indian Agriculture.