Organic amendments restore soil biological properties under pesticides application.

Pesticides are indispensable in modern agriculture, but they also affect soil biological properties and soil sustainability. Although organic amendments (OAs) have the potential to alleviate the negative effects of pesticides and restore soil biological properties, but results have been inconsistent. Here, we conducted a meta-analysis to study the overall effects of OAs on soil biological properties under pesticide application. Our results showed that sole pesticide application significantly decreased soil enzymatic activities (i.e., by -2.5 % for urease, -22 % for β-glucosidase, and - 10 % for dehydrogenase) and reduced microbial population size (e.g., by -6 % for microbial biomass, -10 % for actinomycetes population, -7 % for bacteria and - 12 % for fungi population). Noticeably, sole fungicide application did not significantly affect soil bacteria, fungi and actinomycetes populations as compared to sole herbicide and insecticide. In contrast, pesticide with OAs application significantly increased soil respiration (+60 %), activities of dehydrogenase (+73 %), urease (+80 %) and β-glucosidase (+65 %), microbial biomass (+79 %), bacterial (+65 %) and fungal (+13 %) population sizes than sole pesticide. However, soil acid phosphatase activity significantly decreased (-17 %) by using pesticide with OAs. Our results suggest that OAs in combination with pesticides can modify soil physicochemical properties and subsequently restore soil biological properties, but the magnitude of improvement of specific OAs in combination with individual pesticide classes remains unknown and should be studied in future research.