Integrated Input Management for Improving Nitrogen Use Efficiency and Crop Productivity

摘要

Extensive research since mid-sixties has focused on developing management techniques aimed at minimising N losses and improving nitrogen use efficiency (NUE). Nitrogen losses are recorded to be lower with N fertiliser placement or incorporation in soil, split applications timed with crop demand, slow release N fertilisers, nitrification inhibitors, balanced fertilisation, and conjunctive use with various organics and biofertilisers. Pusa neem micro-emulsion (PNME) technique of coating prilled urea (PU) has been found effective for increasing NUE. Long-term studies have indicated that amelioration of emerging deficiencies of other nutrients, particularly P, K, S and Zn is indispensable for realising full benefits of applied N, and ensuring higher and stable productivity. Exploitation of synergistic interactions between N and other inputs such as water, herbicides (weed control), fuel energy (tillage), high yielding variety (HYV) seeds etc. is the key for increasing input use efficiency. Nitrogen, water and tillage interact among themselves, improve crop yields and hence input-use efficiency. Conservation tillage involving reduced tillage and residue management or mulching with available organic materials has been found beneficial for increased efficiency of various resources including N fertiliser. Manipulation of other non-monetary inputs such as timely sowing, ensuring good initial crop stand and vigour leads to more efficient utilisation of basally-applied N fertilisers, particularly under adverse conditions such as drought and flooding. Genetic variations for NUE have been widely reported within and among crop species, and the high yielding dwarf varieties/hybrids of several crops respond to higher levels of N with improved management. Of late, innovative precision farming techniques have been developed aiming at situation-specific N management using chlorophyll meter, leaf colour charts, fertigation, laser land levelling etc., for increasing NUE. Despite these developments, the NUE continues to be low, and there is a need for a well-coordinated multi-disciplinary team effort in an integrated manner to overcome the various constraints and make increased NUE a reality in Indian agriculture.