Nutrient Budgeting of Primary Nutrients and Their Use Efficiency in India

Abstract

The imbalanced use of fertilizers in India is evident from the fact that the current ratio of nitrogen, phosphorus and potassium in agricultural soil in several states is skewed towards nitrogen. This imbalance causes problems, right from stagnating or declining productivity to soil sickness, widespread deficiency of macro nutrients and micronutrients, and soil alkalinity and salinity. Eventually, it results in reduced efficiency of fertilisers, low yields and low profitability for farmers. Also, nitrogen pollution of surface and groundwater due to excessive fertiliser use has reached alarming levels in several states. Chemical fertilizers are currently the major emitters of nitrous oxide gas, a potent greenhouse gas and ozone depleting substance. Nutrient budget is an important tool to provide an early indication of potential problems arising from nutrient surplus and nutrient deficit. Balanced use of all types of fertilizers, including traditional organic manures and biofertilizers are needed to bring about a change in the prevailing regime that encourages excessive use of chemical fertilizers. However, meeting future food security targets in an over-populated developing country like India, needs to increase the nutrient use efficiency. This ultimately leads to site-specific need-based nutrient application and minimizing nutrient losses from fields. This leads to the 4R Nutrient Stewardship concept, applying the Right Source of nutrients, at the Right Rate, at the Right Time and in the Right Place. This paper provides a historical overview of the nutrient budgeting efforts and systematically reviews major challenges, opportunities, in defining, quantifying, and applying nutrient budgets and improving nutrient use efficiency.