Changes in Pools of Nitrogen under Long Term Conservation Agriculture in Inceptisols of Indo-Gangetic Plains of Bihar

A long-term experiment on conservation agriculture was designed to study different nitrogen dynamics in maize based cropping system at Research Farm, Bihar Agricultural University, Sabour dominated by Inceptisols in eastern Indo-Gangetic plains. The maize based cropping system was studied having various tillage (T1: Zero Tillage; T2: Permanent Raised Bed; T3: Conventional Tillage) and cropping sequences (C1: Maize+Soybean-Wheat; C2: Maize-Wheat; C3: Maize-Maize; C4: Maize-Mustard; C5: Maize-Chick pea; C6: Soybean-Maize) with a special reference to changes in different N fractions. Significant correlation was found between different N fractions (Total N, Ammoniacal-N, Nitrate-N, Total Hydrolysable-N, Hydrolysable ammoniacal-N, Amino Acid-N, Amino Sugar-N, Unidentified-N, Non-hydrolysable N, Available N) and yield as well as N uptake of maize. Zero tillage system under maize-chickpea cropping was found superior in terms of amount of all fractions of N and was also responsible for the improved yield, N uptake, physico-chemical properties and fertility levels of the soils. The organic forms of N, especially total hydrolysable and amino acid N, showed strong positive correlations with available N. Overall, organic N constituted a dominate part of soil N and played key role in soil N cycling and crop production. Not only organic N mineralized into mineral N for plant uptake, it also provided some organic components for plant direct absorption.