Abstract

                                A study was taken up in the existing Long Term Fertiliser Experiment in Tamil Nadu Agricultural University, Coimbatore, conducted since 1972, to study the status and content of various nitrogen fractions both organic and inorganic and the effect on crop yield, uptake by crops and availability of nitrogen in the soil. Exchangeable NII,-N and NO,-N were significantly increased by incremental additions of N. Inclusion of FYM along with inorganic fertilisers, had a positive effect on the buildup of all the organic N fractions. Path analysis revealed that hydrolysable NH-N was the principal fraction for yield prediction in case of finger millet, unidentified hydrolysable -N for erop N uptake and nitrate N to predict the available N in the post harvest soil samples after finger millet.

Key words : Long term fertiliser experiment, Nitrogen, Nitrogen fractions, Yield, Uptake