Short-term impact of arbuscular mycorrhizal fungi and different phosphorus levels on selected soil properties and growth components of two dry bean cultivars in phosphorus-deficient soils

Low yields of dry beans are often associated with lack of inoculation with biofertilisers and deficiencies in soil phosphorus (P). A field experiment was conducted to investigate the effect of arbuscular mycorrhizal fungi (AMF) and P fertiliser on dry bean growth and soil properties in Limpopo province, South Africa. The experiment was laid out in a split-split plot design. The main treatments were: (a) dry bean cultivars (red-speckled and small-white haricot), (b) sub-plot treatments: AMF inoculation (mycoroots) levels (with and without inoculation) and (c) sub-sub plot treatments: different levels of P (0, 20, 40 and 60 kg P ha−1). The soil and plant growth parameters were analysed using Analysis of Variance (p = 0.05). The interaction of cultivar and P levels indicated that P application improved growth and yield of both cultivars and also suggested that the optimum P level for red-speckled beans was 40 kg ha–1 while that of small-white haricot beans was 30 kg ha−1. Red-speckled beans showed greater growth and yield than the small-white haricot beans. There was no clear impact on soil properties in the short term. These results indicate that raising the soil P levels may improve dry bean growth and yield, and red-speckled beans could be a better option for farmers than small-white haricot beans.