造成农药残留的主要原因:一是大量化肥的施用,使蔬菜中产生硝酸盐、重金属等有害物质,同时造成土壤板结、地力枯竭,病虫害日趋严重;二是农药的连年施用使土壤中有严重农药残留,病原菌的抗药性也随之加强。土壤中的病原菌日积月累、越来越多,造成土传病虫害泛滥。所以农药用量越来越大、毒性越来越 The main causes of pesticide residues: First, the application of large amounts of fertilizers, so that vegetables produce nitrate, heavy metals and other harmful substances, while causing soil compaction, depletion of groundwater, pests and diseases become increasingly serious; Second, pesticide application so that the soil has serious pesticides Residues, the resistance of pathogens also will be strengthened. Pathogens in the soil over time, more and more, resulting in the spread of soil-borne diseases and pests. Therefore, increasing the amount of pesticides, toxicity is more and more