Balance sheet of soil nitrogen in wheat (Wticum aestivum)- based crop sequence

Abstract

A field experiment was conducted during 1992-94 at Pusa, Bihar, consisting of 7 rainy-season (kharit) crops, followed by wheat (Triticum aestivum L. emend. Fiori & Paol.). The crop sequence dhaincha [Sesbania cannabinas (Retz.) Pers.] (green manure)]-wheat showed a positive N-balance in soil. Fallow-wheat, blackgram (Phaseolus mungo L.)-wheat, groundnut (Arachis hypogaea L.)- wheat and sesame (Sesamum indicum L.)-wheat crop sequences also showed marginal, but positive N balance in soil at higher levels of nitrogen. However, sorghum [Sorghum bicolor(L.) Moenchl-wheat, rice (Oryza sativa L.)-wheat and maize (Zea mays L.)-wheat sequences showed reduced available N status of soil, regardless of the level of nitrogen. The balance sheet of nitrogen, however, depicted the maximum gain of nitrogen in sorghum-wheat sequence, followed by maize-wheat, blackgram-wheat, groundnut-wheat and fallow-wheat sequences. The gain of nitrogen in balance sheet was more at lower levels of nitrogen.