[Estimations of application dosage and greenhouse gas emission of chemical pesticides in staple crops in China.].

Chemical pesticides play an important role in improving crop yield in modern agriculture. However, commonly overuse of pesticide in China leads to serious environmental problems and food safety hazards. Based on a national questionnaire survey of farmers across China in 2012, the situation of pesticide applications to rice, wheat, and corn in 2011, and their corresponding greenhouse gas (GHG) emissions were investigated. The survey showed that at least 54 types of insecticide, 24 types of fungicide, and 50 types of herbicide were in use across three crops. 32% of rice farmers applied biological pesticides in China. The amounts of pesticides applied to the three cereal crops were 30.8, 16.5, and 58.3 kt for insecticides, fungicides, and herbicides, respectively. The total GHG emission from these pesticides was 1.5 Tg Ce, and the GHG emissions from these insecticides, fungicides, and herbicides accounted for 23.8%, 16.9%, and 59.3% of the total emission, respectively. In south China, the amounts of pesticides applied occupied 51% of the national total. For the production of each kilogram of grain, the amounts of pesticides applied were 0.22, 0.18, and 0.24 g for rice, wheat, and corn, respectively. Therefore, the sums of pesticides applied by crop types were 44.4 kt for rice, 21.4 kt for wheat, and 39.7 kt for corn. Meanwhile, the GHG emissions of pesticides were 665.5, 250.1, and 547.5 Gg Ce for rice, wheat, and corn, respectively. For pesticide types, organophosphorus insecticides accounted for 69% of total insecticide use in China, while benzimidazole, organophosphorus, azole, and organic sulfur fungicides together contributed 87% of total fungicide use. In addition, the use of anilide, organic heterocyclic, and organophosphorus herbicides contributed 85% of the total herbicide application. Therefore, the reduction of pesticide use would play an important role in food safety and environmental safety, and GHG mitigation in agricultural sector in China.