The influence of inoculating earthworm (Pheretima Pingi. ) on
phosphorus availability in red soil was studied by conducting
pot experiments. Various aspects including decomposition of organic materials (rice straw, peanut residue and rape residue), soil total phosphorus and available phosphorus, soil carbohydrate content and soil phosphatase activity were taken into account. In this paper, the effect and mechanism of increasing
phosphorus availability in red soil due to the inoculation of earthwormwere mainly explored. The main results were summarized as follows: (1)
Earthworm activities accelerated the decomposition of organic materials and the biological returning of phosphorus in the soil ecosystems, which made phosphorus in the organic materials a direct part of soil available phosphate. Significance on the decomposition of organic materials is in the descending order of peanut residue>rice straw>rape residue. (2) Variance analysis showed that the available phosphate for all the treatments increased significantly during a 150 day incubation. Differences of the soil available phosphate contents between the treatments with organic materials plus earthworms and the treatments with organic materials but earthworm free were significant. (3) There was a tendency of improving red soil acidity by earthworm. As compared to the soil pH value (pH(H 2O)=4 34) at the beginning of incubation, the pH values increased 0 17 for the treatment with rice straw plus earthworm, 0 35 for the treatment with rape residue plus earthworm and 0 44 for the treatment with peanut residue plus earthworm, respectively. (4) Earthworm activities increased the content of soil carbohydrate. Statistical analysis indicated that the carbohydrate contents in the soil with organic material and earthworm increased significantly. (5) Inoculation of earthworm enhanced soil microbial activities and soil phosphatase activity. The physiological processes of earthworm's swallowing and excreting changed the population types and the quantities of soil microbe. Improvement of the soil phosphatase activity by inoculating earthworm increased the soil organic phosphorus and thus the soil available phosphorus content was raised. The integrative aspects of earthworm activities and its special physiological process enhanced the content of available phosphorus and the phosphate availability of red soil.