Effect of superphosphate and mucuna (Mucuna pruriens) management options on soil organic matter, soil pH and physical properties of a kaolinitic sandy loam soil in Zimbabwe

The continuous use of fertilizer alone will eventually result in deterioration of soil pH, soil organic matter (SOM) and soil physical properties. Inclusion of a leguminous crop such as mucuna (Mucuna pruriens) in a rotational system may alleviate these problems. The major objective of this research was to investigate the effect of two phosphorus application levels and four mucuna management options on SOM, soil pH, bulk density, particle density and porosity. Incorporation of mucuna at flowering stage in combination with addition of 40 kg ha⁻¹ P increased the SOM and porosity and decreased bulk and particle density significantly compared to other treatments. All treatments where mucuna biomass were incorporated into the soil in the absence of any P application resulted in increased soil pH (CaCl₂) levels with values of > 5.2 which will be beneficial for the production of most crops. The incorporation of above-ground biomass of mucuna had positive effects on all soil properties investigated.