Effects of Arbuscular Mycorrhizal Fungi and Earthworm on Nematode Communities and Arsenic Uptake by Maize in Arsenic-Contaminated Soils

The influences of arbuscular mycorrhizal fungi (AMF, Acaulospora spp. and Glomus spp.) and rice straw and earthworms (RE, Eisenia foetida) on nematode communities and arsenic (As) uptake by maize (Zea mays L.) in Ascontaminated soils were examined in a field experiment conducted in Wujiang, Jiangsu Province, China. The experiment was designed as a 2 x 2 factorial with the factors of AMF (inoculated or uninoculated) and RE (added or not added). The results demonstrated that AMP inoculation led to significantly higher root colonization of AMF and root dry weight. Plants inoculated with both AMF and RE had the highest As concentrations in root. The number of total nematodes increased with AMF inoculation when RE was absent, and decreased with RE addition when AMF was inoculated. The improved abundance of nematodes with the AMF treatment implied that the tested AMF acted as food sources for fungivores. The abundances of omnivores-predators and plant parasites were reduced by earthworm activity. Twenty-seven genera of nematodes were identified, with Filenchus dominant in all treatments. Trophic diversity, Shannon-Weaver diversity, Simpson dominance index, and species richness indicated higher species diversity, more proportionate species composition, evenly distributed species, and more food sources in the AMF, RE, and their interaction treatments. Maturity index showed a moderately disturbed environment due to As pollution. Besides enhancing plant uptake of contaminants, AMF and RE amendments could also improve soil health by restoring the structure of soil communities, as reflected by more stable nematode community structure.