Title : The influence of three winter cover crops on nematode biodiversity and soil health
Abstract:
The practice of regenerative agriculture in Limpopo Province arises from the critical challenges in soil health, food security and climate change. Approximately 60% of South African land degraded and significant greenhouse gas emissions linked to conventional farming, there is an urgent need for sustainable agricultural practices that restore soil quality and enhance ecosystem health. The objective of this study was to establish whether Vicia sativa, Raphanus sativus and Avena strigosa each as winter (June-August) cover crop/green manure, will improve soil health under field conditions. A field study was conducted at the University of Limpopo to investigate the effect of winter cover crops, Vicia sativa, Raphanus sativus and Avena strigosa on soil health and nematodes biodiversity. Each on a block of approximately 10×2 m2, within each block, the samples (soil, roots and shoots) were collected in two subplots of 3 m × 2 m2. Soil organic carbon content, enzyme activity, nematode and bacterial functional diversity data were collected from all the plots. Yield was also recorded per winter cover crop (DW). Based on the results, most of the soil from the samples are from degraded, depleted soil with a high C:N ratio, fungal decomposition pathway and conducive to disease. Some samples were from disturbed, N-enriched soil with low C:N ratio, bacterial decomposition pathway and conducive to diseases. High soil organic carbon content, microbial diversity and enzyme activity were observed in Raphanus sativus. In addition, the soils from the samples were dominated by cp-2 nematodes. These nematodes are generally found in most soils and responds well to enrichment and changes in environmental conditions. Yield mass (DW) significantly varied (P≤0.05) among winter cover crops with Avena strigosa plots recording higher yields than Raphanus sativus or Vicia sativa. Based on the results, the investigated winter cover crops had significant effect on population densities of nematodes, and soil health of the soil and biomass. This study has confirmed that growing Vicia sativa, Raphanus sativus, or Avena strigosa individually as winter cover crops (as opposed to using conventional fallow) each successfully enhanced the overall soil health condition profile relative to the control conditions of fallow. Using living covers allowed for a greater degree of biological activation and structural restoration to the soil environment than fallowing and supports long-term ecological resilience.
