Abstract
A field experiment was conducted at research farm, Bihar Agricultural University, Sabour, India during 2017 and 2018 to gain insight crop phonology mediated greenhouse gas emission under different tillage and nitrogen management practices in direct seeded rice (DSR). The experiment was conducted in split plot design with two tillage viz. zero tillage (ZT) and conventional tillage (CT) as main plot and four nitrogen management practices viz. 100% nitrogen through neem coated urea (S1), SPAD based nitrogen management (S2), 75% through neem coated urea + 25% nitrogen through vermicompost, (S3) and ¼ nitrogen as basal and rest in equal three splits at 20, 40, 60 DAS (S4) as sub plot, in three replication. The highest yield (4.69 t ha-1), net return (Rs 46440 ha-1) and B:C ratio (1.44) were recorded from zero tilled DSR. Further, highest yield (4.82 t ha-1), net return (Rs 44880 ha-1) and B:C ratio (1.36) was obtained under split application of nitrogenous fertilizers among other subplot treatments. The range of methane (0.57- 1.47 mg m-2 hr-1) carbon dioxide (0.32- 0.61 mg m-2 hr-1) and nitrous oxide (19.58- 38.79 µg m-2 hr-1) emission was recorded lowest in zero tilled plots and split application of nitrogenous fertilizer also emitted lowest values of 1.59 mg m-2 hr-1 methane, 0.86 mg m-2 hr-1 carbon dioxide and 46.76 µg m-2 hr-1 nitrous oxide at maximum tillering stage of crop growth. Moreover, methane and nitrous oxide emission was gradually decreased from maximum tillering to harvesting stage. Zero tilled DSR with split nitrogen fertilizer application ascribed lowest greenhouse gas intensity among the other crop establishment and nitrogen management options. Thus, zero tilled method of crop establishment with split application of nitrogenous fertilizer could be a remunerative and environmentally stable method for direct seeded rice cultivation.