Experimental evaluation of the potential of arbuscular mycorrhiza to modify nutrient leaching in three arable soils located on one slope

Abstract Arbuscular mycorrhizal fungi (AMF) were previously shown to decrease nutrient losses by leaching from grassland soils, but no information is available for arable soils. Therefore, the objective of our study was to evaluate the potential of arbuscular mycorrhiza to modify nitrogen and phosphorus cycling including nitrate and phosphate leaching in arable soils. To this end, we established a pot experiment with maize ( Zea mays L.) grown in three soils sampled along a sloping field and differing in phosphorus availability and texture. The plants were either inoculated with the native microbial community of the soil, with a pot-cultured AMF isolate, or grown without AMF. Phosphate and nitrate leaching varied among the three soils according to phosphorus availability and plant growth, both being highest in the soil with the highest sand and phosphorus contents. Nitrate leaching was significantly increased by the soils' native microbial communities, which induced higher net nitrification rates as compared to the treatments inoculated with the pot-cultured microbial communities. Mycorrhiza was formed in all three soils after AMF inoculation, with low to intermediate root colonization levels. However, it had no effect on plant growth or nutrient uptake in any of the three soils, which was consistent with a significant nitrogen deficiency of the maize plants. The absence of mycorrhizal effects on nitrate and phosphate leaching is discussed within this context, and the potential of arbuscular mycorrhiza to reduce nutrient leaching from arable soils is concluded low.