Mucuna pruriens L. (DC) and Arachis hypogaea (L.) enhance soil biological and chemical properties of nutrient-deficient small-scale sugarcane soils.

Abstract

Most of the rural population in South Africa rely on agriculture for food security and livelihood. In KwaZulu-Natal, sugarcane production plays a significant role in the livelihoods of smallscale farmers in rural areas. However, there has been a decline in sugarcane productivity and yield due to soil-health-related problems caused by long-term monoculture and excessive chemical fertilizer use. Legume cover cropping is an attractive and sustainable alternative to reduce overreliance on synthetic nitrogen (N) fertilizers since legumes increase soil N levels through symbiotic N fixation. Mucuna pruriens L. (DC) and Arachis hypogaea L. have been reported to fix approximately 34-242 kg N ha-1 and 150-200 kg N ha-1, respectively. Furthermore, these legume species have been reported to provide ecosystem services such as nutrient cycling, weed suppression, soil erosion control, increased organic matter, and microbial diversity. Therefore, this study investigated the effects of cultivating M. pruriens and A. hypogaea on the soil chemical characteristics, bacterial community composition, and enzyme activities of five different acidic and nutrient-deficient sugarcane plantation soils in KwaZulu-Natal, South Africa. Additionally, the study evaluated the N-source preference, biomass accumulation, and plant nutrition of M. pruriens and A. hypogaea growing in these acidic and nutrient-deficient sugarcane soils. Post-harvesting, the soil pH increased across all study sites for both legume species. Both M. pruriens and A. hypogaea sanctioned for Ncycling, N-fixing, and P solubilizing bacteria with the dominant strains belonging to the Burkholderia and Pseudomonas genera. The increase in P solubilizing bacteria, alkaline and acid phosphatase activity assisted with the demands of biological N fixation, allowing M. pruriens and A. hypogaea to fix 26-58% and 40-70% of N from the atmosphere, respectively. Overall, the findings of this study showed that M. pruriens and A. hypogaea contribute to soil health improvement by reducing soil acidity and increasing the diversity of nutrient-cycling bacteria and their associated enzyme activities in small-scale sugarcane soils.