Effects of crumb rubber waste as a soil conditioner on the nematode assemblage in a turfgrass soil

The impacts of waste crumb rubber soil amendment on nematode abundance, community structure and soil characteristics were studied in pot grown Lolium perenne L. Three treatments, no crumb rubber (CK), 10% and 15% crumb rubber (CR), were arranged in a randomized complete design. After 3 months’ turfgrass growth, soil nematodes were extracted and identified to genus level, and populations of total, bacterivorous, fungivorous, omnivorous, predatory and plant parasite nematodes were counted. Genus diversity, richness, evenness, plant parasite index (PPI) and maturity index (MI) were calculated to compare nematode community structure. Thirteen genera of soil nematodes in all treatments were identified, of which Helicotylenchus was dominant. Crumb rubber incorporation significantly decreased plant parasite and omnivorous nematode populations, but increased the abundance of predatory nematodes. However, fungivorous and bacterivorous nematode populations were not significantly affected by crumb rubber amendment. Pots treated with 15% CR had the lowest number of plant parasite, omnivorous nematodes and the highest number of fungivorous, predatory nematodes. Shannon's diversity index (H′), evenness (J′), PPI and PPI/MI reduced in pots receiving crumb rubber, whereas dominace (λ) and maturity index (MI) increased in crumb rubber treatments. In addition, CR application decreased soil bulk density and pH value, but increased soil moisture.