Productivity, profitability and greenhouse gas emission from rice-wheat cropping system under different tillage and nitrogen management practices

A field investigation was carried out at experimental farm of Bihar Agricultural University, Sabour, Bhagalpur, India. The treatments consisted of two tillage practices viz. zero and conventional tillage as main plot and four nutrient management viz. 100% inorganic fertilization, SPAD based nitrogen management, 25% of N supplement with vermicompost and split application nitrogen as sub plot. The highest rice equivalent yield (92.1 q ha⁻¹), system productivity (25.23 kg ha⁻¹ day-1) and B:C ratio (1.67),was recorded under zero tillage treatment as compare to conventional treatment. Further, rice equivalent yield (91.9 q ha⁻¹), system productivity (25.18 kg ha⁻¹ day-1) and B:C ratio (1.60), was maximum under split application of nitrogenous fertilizer. Minimum amount of total seasonal methane (48.89 kg ha⁻¹ in kharif and 6.25 kg ha⁻¹ in rabi), carbon dioxide (38.26 kg ha⁻¹ in kharif and 157.03 kg ha⁻¹ in rabi) and nitrous oxide (1.60 kg ha⁻¹ in kharif and 21.67 kg ha⁻¹ in rabi) emission was obtained from zero tilled plots and splited top dressing of nitrogenous fertilization emitted lowered methane (55.44 kg ha⁻¹ in kharif and 5.52 kg ha⁻¹ in rabi), carbon dioxide (40.39 kg ha⁻¹ in kharif and 147.52 kg ha⁻¹ in rabi) and nitrous oxide (1.61 kg ha⁻¹ in kharif and 19.35 kg ha⁻¹ in rabi). Zero tillage with split application of nitrogenous fertilizer could be an environmentally viable, productive and economically profitable option.