Accumulation Of Manganese And Zinc In Cucumber Planted Soil With The Successive Applications Of Mancozeb

Agrochemicals are widely-used in agriculture and have made a great contribution to the development of world agriculture and food supply. Pesticides have played great contribution to us for the control of pests and thus crop yields. However, the intensive application of pesticides has caused some problems such as resistance、 residues、resurgence and the accumulation of heavy metals in soils. Herein, a study concerning the dissipation, residual characteristics, accumulation of Mn and Zn was conducted in a greenhouse for the production of cucumber after the application of the Mn and Zn contained fungicide mancozeb.No accumulation of mancozeb was found in soil with the four successive applications of the fungicide at the recommended dosage (3.75kg ha-1). However, mancozeb was accumulated gradually after its repeated applications at double recommended dosage (7.50kg ha-1) The level of mancozeb measured fifteenth day after its forth application at double recommended dosage was about90.63%times of that measured tenth day after its first application. Dissipation of mancozeb at levels of3.75kg ha-1and7.50kg ha-1on cucumber was fitted to the first-order function with the half-lives3.3d,11.44d, respectively.The accumulation of Zn was not observed in soil successive applied with mancozeb at both dosages of single and double recommended. However, the Mn was found to be accumulated gradually with the repeated applications of mancozeb at double recommended dosage. The level of Mn measured ninth day after its forth application at double recommended dosage was about5.98%times of that measured tenth day after its first application.Avoidance behavior of Eisenia fetida was only observed in the soil fortified with mancozeb at concentration of1500mg kg-1, suggesting the low toxicity mancozeb to earthwarm. The low toxicity of mancozeb was concluded from the germination experiments of wheat and cucumber with its applied soil. The successive applications of mancozeb did not result in any increase in micronucleus frequence of Vicia faba, whereas the pollution index (PI) was increased with the repeated applications of the fungicide.