Revitalizing maize production through managing biological N fixation, soil acidification and nitrous oxide emission from legumes in tropics
Markos Daniel, Yoseph Tarekegn
Abstract
Legume associations address challenges related to soil fertility and land degradation commonly encountered in maize monocultures. However, it's important to note that legumes contribute to the production of both nitrous oxide (N2O) and hydrogen ions (H+). In our examination of 693 manuscripts published between 1941 and 2023 to document the benefits of legumes in maize-based cropping systems, we identified and included 195 credible journal publications in our analysis. The findings revealed that, apart from fixing 50 to 320 kg nitrogen (N) ha-1, legumes offer various non-N advantages. When compared to maize grown after maize, a 2.4 to 173% greater yield of maize was recorded, corresponding to a 9 to 96.7% increase in biomass when maize is grown after legumes. The most substantial increases were observed in farms employing reduced tillage, residue retention, and suitable legumes. Intercropping maize with legumes, as opposed to solitary maize production, resulted in 4.3 to 80% higher biomass, 5 to 14.8% higher grain yield, and 5 to 29.5% higher profit. However, it's important to acknowledge that acid and N2O production ranged from 0.2 to 2.7 mol H+kg-1 biomass produced and 5.6 kg N2O ha-1, respectively. Implementing compatible cropping systems, increasing soil N mineralization, and recycling crop residues can enhance biological N2 fixation, reduce acid buildup in soils, mitigate N2O emissions, and simultaneously improve maize yield. In conclusion, the review underscores the necessity for location-specific cropping system standards and regulations to ensure the sustainability of maize-legume cropping systems. Key words: Cropping system, legumes, nitrous oxide, residue management, soil acidification.