Effects Of Herbicide Acetochlor On Community Of Soil Animal In Farmland Soil

Soil animals were important consumers and special decomposers in terrestrial ecosystem, and they were unusually indicative to ecosystem. And soil animals were essential part of soil environment. It was involved in many aspects of organic matter decomposition, partial regulation of microbial activities, nutrient cycles and crumbly structure.The application and development of chemical herbicide had increased crop yield and quality, at the same time it leaded to a serious problem of environment. From the references we learned herbicide acetochlor pollution caused by transportation in the soil resulted in both qualitative and quantitative changes in animals, which directly affected soil function. Soil biological properties were an important index in indicating soil quality.Herbicide acetochlor polluted experiment on the farmland soil was taken. The results were summarized as follows:We collected soil animal 3802 ind., which subordinated to 6 Phyla, 10 Classes, 14 Orders, 38 Families, that Portozoa, Oribatia and Nematoda were domination population, their frequncies were 31.85%,10.07%,38.19%, accounted for 80.12% of the total animals, while the rest were either averaged or rare in population. The laboratory experiment showed: There existed a close relationship between the concentration of herbicide acetochlor and the species and quantities of soil animals, with the increasing of Acetochlor concentration, the species and quantities of soil animals significantly decreased ,as well as the Shannon-Wiener index (H'). The index was 2.2048 at the control; it was 2.0985 at the low Concentration; it was 1.5844 at the high Concentration.In this polluted experiment, the species of soil animals was decreased with decreasing common population and rare population, while the amount change of soil animal was associated with the amount change of the dominant populations of Protozoa, Nematode and Oribatida. With the increasing of Acetochlor concentration, the Nematoda population significantly reduced, so Nematode was used as one of bioindicators of changes in agroecosystems. From the infectant time of Acetochlor herbicide, the species and quantities of soil animals had changed after 24,48,72,96,120h, but the change was not obvious. Toxicity test of earthworm showed that acetochlor herbicide has influences obviously on earthworm, their LC₅₀ were 4.3302ml/L,1.8395ml/L and 1.4121ml/L for 24 hours, 48 hours and 72 hours respectively. Safe concentration calculated of earthworm was 0.0996ml/L. This research provided scientific basis for reducing the agroecological environmental pollution.