Print PageThe aim of this study was to investigate the effect of reusable organic wastes on the soil food web and trophic cascade. Bone meal, de-oiled cake, and oyster shell were applied at 5 t ha-1, and the abundance and biomass of soil organisms were measured at 4, 8, and 13 weeks after the treatments in soil under eggplant cultivation.
Results/Conclusions
The biomass and abundance of bacteria were the highest in the bone meal treated soils. Increase in the abundance of bacterivorous nematodes was observed under treatment with the bone meal and de-oiled cake, but there was little change in the abundance of omnivorous and predatory nematodes. A response of microarthropods in the Collembola and Oribatida was apparent, and these organisms are involved as secondary consumers in the soil food web, but the predaceous Prostigmata were relatively unaffected. The lack of a positive relationship between the abundance of soil organisms and plant growth suggested that an increased activity of soil organisms may not necessarily lead to an increase in plant growth according to the quality of applied organic wastes. The abundances of protozoa, microbivorous nematodes, Collembola, and Oribatida were correlated with the phospholipid fatty acid (PLFA) indicators for bacteria and fungi, indicating that bacteria- and fungi-based food webs formed simultaneously. Meanwhile, the abundances of the secondary consumers were not significantly correlated with those of the predators. The study suggests that, in the short term, organic waste alters the trophic cascade between the primary and secondary consumers through bottom-up control, but its effect may not extend to predators.
