Root and arbuscular mycorrhizal effects on soil nutrient loss are modulated by soil texture

Despite their importance, there is a lack of knowledge on the impact of forming arbuscular mycorrhizas (AM) on soil phosphorus (P) leaching in soils with different textures. Therefore, the objective of this study was to investigate the impacts of mycorrhizal and non-mycorrhizal roots on P leaching in two non-sterilised soils of contrasting texture. A mycorrhiza-defective tomato (Solanum lycopersicum L.) genotype (named rmc), and its wild-type progenitor that is able to form AM (named 76R), were used to investigate the effects of AM on soil P loss via leaching. Concentrations of reactive and un-reactive P in the leachate and soil were measured and related to plant growth, plant P uptake, soil water relations and leachate dissolved organic carbon (DOC) concentration. Soil texture affected mycorrhizal colonization, plant growth and plant P concentration, and influenced the concentration and chemical composition of P and the concentration of DOC leached. The chemical composition of P leached and P remaining in soil varied with soil texture, the presence or absence of roots, and their arbuscular mycorrhizal status. Mycorrhizal plants reduced P lost via leaching in the sandy soil substrate, where DOC leached was also high. The roots, regardless of mycorrhizal colonization, appeared to have the greatest impact on increasing P and DOC leached. Taken together, this study provides new insights into the role of AM on soil P loss via leaching in soils of contrasting texture.