Interaction of earthworms and amfungi on maize growth, and nutrogen
and phosphorus uptake

【Objectives】Earthworms and arbuscular mycorrhizal fungi(AMF) are in different trophic levels, both play same roles in promoting plant growth and soil biological fertility. This research on the effect of interaction of earthworms and amfungi improving plant nutrient uptake could explore the potential for soil biological fertility in the sustainable agricultural system. 【Methods】A soil buried pot experiment was carried out with maize as tested crop. Two P levels of 25 mg/kg (low) and 175 mg/kg (high) were setup using KH2PO4 as P source. With each P level, inoculation of AMF or not, and added earthworms or not were setup. The growth and nutrient uptake by maize were investigated, the availability of soil nutrients were measured. 【Results】 AMF and earthworms interactively increased maize shoot and root biomass at harvest. The AMF treatment significantly enhanced colonization and vesicle frequency, hyphae frequency. The earthworm×AMF treatment clearly improved maize root colonization rate as well as arbuscular frequency, hyphae frequency, and hyphal length density except for vesicle frequency which was reduced. At both P rates, shoot and root N and P contents in the earthworm×AMF treatment were significantly higher than those in other treatments. At low P rate, the increase of shoot N and P contents were by addition of both AMF and earthworms, while that in root P content was mainly by addition of AMF, root N content was not affected by AMF or earthworm treatment. At high P rate, earthworm treatment significantly increased shoot and root N and P contents AMF treatment did not. At high P rate, earthworm and AMF interaction also increased soil microbial biomass C, which possibly improved root N and P contents and indirectly increased the shoot N and P uptake. At low P rate, soil N mobilization by earthworms might have reduced potential N competition by arbuscular mycorrhizal hyphae, resulting in greater plant shoot and root biomass. Earthworms and AMF interactively enhanced soil N and P availability, leading to greater nutrient uptake and plant growth.【Conclusions】 In both high and low P supply levels, the earthworms and AMF have positive interactions on improving the biomass and the N and P uptake of maize, and the soil micro biomass carbon and nitrogen contents. In high P supply (175 mg/kg), the interaction of earthworms and AMF is able to adjust the soil microbiomass C and N content for the growth of maize. In low P supply (25 mg/kg), the AMF mainly involves in the release of P, while earthworms in the mineralization of straw and soil organic N, both the work help each other for the supply of maize growth.