Abstract
Cajanus cajan (Pigeon pea) enhances soil nutrition by increasing bacterial communities and their associated enzyme activities, creating optimal conditions for the growth of succeeding crops like Eragrostis curvula (Weeping Love Grass). This study explored the viability of rotating C. cajan and E. curvula and assessed their effects on soil nutrient cycling. Cajanus cajan and E. curvula were monocropped and rotated in soils collected from Jameson Park, Kaydale, and Rensburg, Gauteng, South Africa. Pre-planting and post-harvest soil analyses were done to determine the nutrient concentrations, pH, total cation concentrations, exchange acidity, enzyme activities, and bacterial identification. Furthermore, the growth kinetics and nitrogen (N) source reliance of C. cajan and E. curvula were determined. Cajanus cajan and E. curvula selected for different bacterial genera in their rhizosphere soils. Cajanus cajan selected for Pseudomonas , Novosphingobium , Paraburkholderia , Burkholderia , and Croceiccocus genera, while E. curvula selected for Pseudomonas , Flavobacterium , Pedobacter , Arthrobacter , Pseudoarthrobacter , and Luteimonas species. The rotation of C. cajan and E. curvula selected for Pseudomonas , Caulobacter , and Pedobacter genera. Monocropped C. cajan significantly increased nitrate reductase, β-glucosidase, and acid and alkaline phosphatase activities compared to rotation treatments and E. curvula monocropping. Cajanus cajan primarily derived N from the atmosphere (NDFA), with 62.67%, 63.38%, and 62.04% in Jameson Park, Kaydale, and Rensburg soils, respectively. Rotated E. curvula showed higher reliance on NDFA and had higher plant N and P concentrations than in monocropping. This study highlights the role of C. cajan in enhancing soil nutrient dynamics, suggesting its rotation with E. curvula can yield multiple benefits for subsistence farmers in impoverished communities.