Evaluation of Nitrogen Supplying Power of Some Soils of Delhi State

The Iowa nitrification method and standard incubation method, which determine mineralisable nitrogen, have shown significant correlation between soil test values and percentage yield on one hand and with uptake of nitrogen at flowering stage on the other hand. Amongst the chemical methods tried, organic carbon was found to be the best index for nitrogen availability to wheat in some soils of Delhi State. The release of nitrogen by different methods in surface and subsoil samples bears no relationship except in case of organic carbon determination.