Effect of arbuscular mycorrhizal fungi on aggregate stability of a clay soil inoculating with two different host plants

Abstract

Reductions in pore space caused by soil compaction considerably impact soil permeability to air and water by crop roots. The inoculation of arbuscular mycorrhizal (AM) fungi to alleviate this problem has been explored around the world. A pot experiment was conducted to assess the effects of AM fungi inoculation on the growth of two crops, tomato (Solanum lycopersicum L.) and maize (Zea mays L.), and the soil structure in a clay soil (lime concretion black soil). The results showed that AM fungi inoculation increased shoot nitrogen (N) and phosphorus (P) concentrations of maize by 32.4% and 17.0%, respectively. Soil alkali-hydrolyzable N and Olsen-P were 30.1% and 29.9% higher, respectively, in inoculated maize plants than in the corresponding uninoculated treatments for 30 days. No effect of AM fungi on nutrient uptake and soil-available nutrients was found for tomato plants. The NMWD (normalized mean weight diameter, an index to evaluate soil aggregates) values for tomato and maize plants inoculated with AM fungi were 46.2% and 17.7% higher, respectively, than uninoculated plants and the same trends were detected for soil organic carbon (SOC) content. A significant positive relationship was found between SOC and NMWD, indicating that increasing SOC might be one mechanism by which AM fungi improved soil structure. Our results suggested that AM fungi might not always benefit plant growth and nutrient absorption after inoculating for 30 days, but contributed to soil structure improvement even with low colonization.