Sustainability of fallow - Indian mustard (Brassica juncea) system as influenced by green manure, mustard straw cycling and fertilizer application

A field experiment was conducted for five consecutive years (2005–06 to 2009–10) to evaluate the effect of dhaincha (Sesbania aculeata) green-manuring (GM), mustard [Brassica juncea (L.) Czern & Coss] straw cycling and fertilizers on productivity and sustainability of mustard under fallow–mustard sequence. Sesbania (GM) and mustard straw cycling significantly influenced plant height, branches/plant, siliquae/plant, seeds/siliqua as well as seed and oil yields compared to existing fallow-mustard practice. The pooled mustard seed yield registered 42.3% increase due to Sesbania (GM) alone and 63.9% due to green manuring + mustard straw cycling. Increase in fertilizer levels from 40 kg N to 80 kg N and 8.7 kg P to 17.4 kg P significantly improved mustard yield attributes and seed and oil yields, while results of K application were inconsistent. The combined application of 80 N + 17.4 P + 33.3 K kg/ha synergistically increased the seed yield by 82.1% over 40 N + 8.7 P kg/ha. Supplementary use of balanced fertilizers (80 kg N: 17.4 kg P: 33.3 kg K) to either of organic treatments, synergistically improved the seed yield at least by three-fourth times. Sustainability yield index, partial factor productivity, production efficiency and incremental benefit cost ratio also showed significant improvement due to Sesbania (GM), mustard-straw cycling and judicious fertilizer use.