Carry-over effect of brown manuring supplemented with nitrogen on productivity and profitability in succeeding wheat (Triticum aestivum)

A field experiment was carried out on wheat (Triticum aestivum L.) (2017-18) in succession to maize (Zea mays L.) crop grown with several brown manuring (BM) practices (2017) at ICAR-Indian Agricultural Research Institute, New Delhi. The field layout was fixed for both maize and wheat. The 12 brown manuring/weed control treatments adopted in maize were taken as main plot treatments, and three levels of N, viz. 0, 60 and 120 kg N/ha were taken as sub-plot treatments. At 40 DAS, with respect to weed control, all BM/weed control treatments were inferior to weed-free control, which was freshly employed in both seasons, but was superior to un-weeded control. Among the BM treatments, the Sesbania + Crotalaria mixture (12.5+12.5 kg/ha) and 2,4-D applied at 35 DAS resulted in lowest total weed density (similar to 31.8/m(2)), which was 46.5% lower than that in the un-weeded control. Total weed density was positively correlated with N level. Total weed density was highest at the highest dose of nitrogen at 120 kg/ha (similar to 37.1/m(2)) and was significantly higher than those in no nitrogen (similar to 32.0/m(2)). Sesbania + Crotalaria mixture (12.5+12.5 kg/ha) and 2,4-D applied at 35 DAS was superior to others with respect to wheat's ear bearing tillers (419.6), grains/spike (49.1), 1000-grain weight (40.3 g), harvest index (38.5%), grain yield (4.41 t/ha) and biological yield (11.42 t/ha), gross returns (111500 (sic)/ha) and net returns (80600 (sic)/ha). This treatment also resulted in higher grain yield (4.80 t/ha) and net returns (89400 (sic)/ha) than other treatments at 60 kg N/ha, and was at par with weed-free control with 120 kg N/ha (5.19 t/ha and 92200 (sic)/ha, respectively). Therefore, the carry-over effects of 1:1 mixture of Sesbania bispinosa and Crotalaria juncea (12.5+12.5 kg/ha) and 2,4-D 0.5 kg/ha applied at 35 DAS in combination with 60 kg N/ha can lead to higher wheat productivity and profitability.