Biological Nitrogen Fixation of Cowpea in a No-Till Intercrop under Contrasting Rainfed Agro-Ecological Environments

Abstract

Nitrogen (N) availability under no-till intercropping systems has not been widely investigated in diverse agro-ecological regions in Limpopo Province. Two seasons of rainfed experiments were conducted during 2018/19 and 2020/21 in a 2 × 4 × 2 factorial design to measure the biological nitrogen fixation (BNF) ability of cowpea in an intercropping system with four grain sorghum cultivars at two test locations, Ofcolaco and Syferkuil, of Limpopo Province using the natural abundance technique. The cowpea nitrogen isotope composition (δ 15N‰) ranged from 0.2 ‰ to 4‰ at Ofcolaco, whereas at Syferkuil, the range was 2 ‰ to 7 ‰. The N derived from air (Ndfa) was from 35% to 92% at Ofcolaco and 4% to 70% at Syferkuil during the two cropping seasons. The amount of N2 fixed across locations and seasons ranged from 1 kg ha−1 to 71 kg ha−1. In the intercropping system, cowpea fixed more N at higher densities compared with lower densities at the two experimental sites. Biomass was significantly correlated with N accumulated by cowpea (r2 > 0.9) at all locations and across seasons. N accumulated in sole cultures was 30% more at Ofcolaco and 36% more at Syferkuil compared with binary cultures. Furthermore, the treatment combination, cowpea density, as well as cropping system, significantly affected N fixation and accumulation. For high productivity, cowpea intercrop with grain sorghum cultivar Enforcer is recommended, as both crops complemented each other when intercropped. The research should investigate further the root distribution and biomass production of sorghum and cowpea, as well as their impact on N intake.

Understanding the Impact of the Intercropping System on Carbon Dioxide (CO2) Emissions and Soil Carbon Stocks in Limpopo Province, South Africa

“…Te seasonal variability efect on soil physical and chemical properties was also observed in this study. Additional information on the variation across the seasons is outlined by Mogale et al [31]. Across all cropping seasons of test locations, cropping system did not afect P, K, Ca, Mg, Zn, Mn, and Cu.…”

Harnessing the Mineral Fertilization Regimes for Bolstering Biomass Productivity and Nutritional Quality of Cowpea (<i>Vigna unguiculata</i> L. Walp)

“…Although, mineral fertilization plays strategic role in improving soil fertility and crop yields, however, their inappropriate use is linked to green-house gaseous emissions along with soil and water pollution owing to rapid mineralization (Sánchez-Navarro et al, 2021). The integrated use of NPK fertilizers in optimized doses have become critical for restoration of ecological functioning and prevention of environmental degradation (Galindo et al, 2022;Mogale et al, 2023;Dimande et al, 2024). Among macronutrients, N and phosphorous (P) are essential nutrients for legumes growth due to their vital roles in triggering vegetative growth (through improved nutrients uptake and photosynthesis rate) and roots development (due to enzymes activation and traslocation of assimilates from leaves towards roots), respectively (Yildirim et al, 2022).…”

Additional organic and bacterium fertilizer input regulated soybean root architecture and dry matter distribution for a sustainable yield in the semi-arid Region of China

“…They are an essential component of leaves during plant growth [ 1 , 2 ], and changes in available nutrients in the soil microbial environment significantly affect the physiological adaptability of plants to abiotic stress [ 3 ]. The storage and cyclic utilization of soil microorganisms have a decisive impact on crop nutrient absorption, the migration of rhizosphere microbial ions, and the stability of productivity in cultivated soil [ 4 ]. Overall, soil microorganisms effectively stimulate hormone synthesis and promote the growth of plant leaves and roots, thereby enhancing the conversion efficiency of photosynthetic products for sustainable production [ 5 ].…”