The degradation trends of high effect cypermethrin in soils.

Under laboratory conditions, the degradation trends of two high effect cypermethrin isomers in soils were studied. Their contents in soils were diminished gradually with the time. Without thinking the action of microbe in soils, the stability of 3 kinds of pesticide had definite relation with the contents of organic matter and pH value in soils. The half-life values of alpha-cypermethrin and theta-cypermethrin in black soil were 7.95d and 5.35d; in Henan fluvo-aquic soil were 13.2d and 6.87d; and in Jiangxi red soil were 30.3d, 15.9d respectively. The microorganisms in 3 kinds of soils preferentially degraded the theta-cypermethrin and were more stable in the acid soil.