Effects of organic amendments on greenhouse gas emissions and productivity of mungbean under subtropical field conditions

Abstract

Agricultural practices contribute a significant proportion of greenhouse gas (GHG) emissions, notably carbon dioxide (CO 2 ) and nitrous oxide (N 2 O) released through the application of fertilizers. Organic amendments have the potential to support sustainable crop production as well as reduce such emissions. This study investigates the effect of organic amendments and inorganic NPK fertilizer on mungbean cv MN-98 yield, yield attributes, and CO 2 and N 2 O in subtropical field conditions. The experiment consisted of six treatments, including control (T1), farmyard manure (T2), Compost (T3), poultry manure (T4), green manure (T5), and inorganic NPK (T6), arranged in a Randomized complete block design (RCBD) with three replicates. Results showed that the maximum GHG emission of N 2 O (0.08 kg ha −1 ) after fertilization was recorded from NPK relatively higher than poultry manure (0.05 kg ha −1 ), while the maximum CO 2 emissions (12.23 kg ha −1 ) were observed from the plot treated with farmyard manure and poultry manure (10.49 kg ha −1 ). However, NPK produced higher crop yield (1152.8 kg ha −1 ) and yield attributes compared to organic manures. Among the organic amendments, poultry manure applied at 10 t ha −1 performed best, producing a grain yield of 1062.1 kg ha −1 , which was 456.8 kg ha −1 (75.5%) higher than the control (605.3 kg ha −1 ). The highest nitrogen concentration (3.6% grain, 2.2% straw) and N uptake (43.7 kg ha −1 ) were observed in NPK, followed by poultry manure (3.5% grain and 2.1%straw, 39.6 kg ha− 1). Overall, the results indicated that poultry manure produced a grain yield comparable to that of inorganic NPK (1062.1 vs. 1152.8 kg ha −1 ) and significantly reduced N 2 O emissions. Although CO 2 emissions were higher than under NPK, while maintaining favorable effects on plant and soil nitrogen dynamics.