The role of faba bean (Vicia faba L.) in the dynamics of phosphorus fractions in the biologically- and conventionally-managed soils

[Truncated abstract] Faba bean (Vicia faba L.) was reported to be an important legume species that could mobilise insoluble phosphorus (P) and acquire more soil P than other legumes or maize, and had a greater proportion of total biomass in roots compared to other species. These properties would make faba beans suitable for the P-deficient soils such as those in the agricultural areas of Western Australia. There is a potential that soil incorporation of faba bean residues could increase P availability for the subsequent crops, which would be particularly significant in soils managed in a biological way, with green manure and/or crop residues being an important source of nutrients. However, the role of faba beans in the dynamics of P fractions in the biologically- and conventionally-managed soils is not known. Therefore, the objective of this study was to assess the dynamics of P fractions in the bulk soil as well as in the rhizosphere of faba beans grown in soils differing in management practice, i.e. with (biological soil) or without green manure phases in rotation (conventional soils). In the preliminary study, five biologically-managed soils contained on average a higher proportion of inorganic-P fractions (65% of Ptotal) than three conventionally-managed soils (59%). Soils from Esperance region (south-eastern part of Western Australia) were chosen for further experiments because the conventionally- and biologically-managed soils from this area had similar basic properties and the P fractions were apportioned in a similar way.