Rice straw biochar and phosphorus inputs have more positive effects on the yield and nutrient uptake of Lolium multiflorum than arbuscular mycorrhizal fungi in acidic Cd-contaminated soils.

The purpose of the study was to examine biochar amendment, phosphorus (P) fertilizer and arbuscular mycorrhizal fungi (AMF) on the yield, nutrient and cadmium (Cd) absorption of Lolium multiflorum in acidic soil. It was shown that mycorrhizal inoculation had no positive influence on the plant shoot biomass and the contents of nitrogen (N), P, potassium (K), calcium (Ca) and magnesium (Mg) in plants at all biochar and P level treatments. Irrespective of mycorrhizal inoculation and P level, biochar amendments markedly elevated the soil available P and K uptake in plant tissues. In contrast, biochar significantly decreased the translocation factor of plants, soil exchangeable Cd, and acid and neutral phosphatase activities, regardless of the mycorrhizal inoculation and P fertilizer. Without P fertilization, biochar amendments significantly promoted shoot P content, while biochar amendments significantly reduced shoot P content when P fertilizer was applied. Without biochar application, P fertilizer application significantly promoted the biomass and N uptake of shoots in both AMF inoculation treatments, while P fertilizer increased these only in the presence of biochar and mycorrhizal inoculation. The increased N content induced by the biochar amendment elevated the shoot N:P ratio and alleviated the N deficiency with P fertilizer input. Thus, we concluded that the addition of biochar and P fertilizer showed more positive effects on the promotion of growth and nutrient uptake of L. multiflorum than AMF grown in acidic Cd-contaminated soils.