Effects of irrigation, phosphate fertilizers, and arbuscular mycorrhizal fungal interaction on soil nutrient content in alfalfa fields

Soil nutrient content is an important factor affecting the quality and high yield of alfalfa (Medicago sativa). In order to explore the effects of irrigation, phosphate fertilizers, and arbuscular mycorrhizal (AM) fungi on soil nutrients in alfalfa fields, two irrigation treatments, namely regulated deficit irrigation (RDI) and quota irrigation (QI), four fertility gradients generated by applying 0 (P₀), 60 (P₁), 120 (P₂) and 180 kg·ha⁻¹ (P₃) of phosphate fertilizer, as well as two treatments, namely AM (soil can not kill AM fungi) and –AM (soil can kill AM fungi), were set up in this study. The results showed that QI treatment increased the available phosphorus content in rhizosphere and non- rhizosphere soil, and the application of phosphorus fertilizers and AM treatment significantly increased the total phosphorus and available phosphorus content in the soil. The available phosphorus content in rhizosphere soil at 0－20, 20－40 and 40－60 cm layers was higher than that in non-rhizosphere soil, indicating that AM fungi contributed considerably to the available phosphorus content in alfalfa rhizosphere and non-rhizosphere soil.