[Effects of Organic Amendment Application on Extracellular Enzyme Activities and Soil Fertility Level in Aeolian...

This study was conducted in 2010 in the irrigated aeolian sandy soil area of Hetian County， Xinjiang Uygur Autonomous Region to investigate the long-term effects of different organic amendments on the physicochemical properties and extracellular enzyme activities of aeolian sandy soil. Four treatments were established： no organic amendments （CK）， 1% biochar application （22.5 t·hm^-2， B1）， 10% biochar application （225.0 t·hm^-2， B2）， and 1% manure application （22.5 t·hm^-2， M）. Spring maize was cultivated during the experimental period， and the application rates of chemical fertilizers and agronomic practices were consistent with local agricultural practices. In 2023， soil samples from the 0-20 cm plow layer were collected to measure soil physicochemical properties and extracellular enzyme activities. The results showed that organic amendments significantly improved the physicochemical properties of aeolian sandy soil， with manure treatment demonstrating the most pronounced effects. Compared to those in the CK， manure application markedly increased soil organic carbon （43%， P<0.05）， total nitrogen （55%， P<0.05）， field water holding capacity （14%， P<0.05）， and microbial biomass carbon （154%， P<0.05）. The application of manure alleviated microbial carbon limitation and balanced nitrogen-phosphorus nutrient demands by providing available carbon and effective nitrogen. In contrast， biochar exacerbated microbial nitrogen limitation due to its high carbon-to-nitrogen ratio and nitrogen adsorption capacity. Based on the observed results， manure application is optimal for improving the physicochemical properties， enzyme activities， and microbial nutrient balance of aeolian sandy soil. For biochar， its application requires optimization of nitrogen fertilizer dosage to avoid aggravating nitrogen limitation. In conclusion， this study elucidates how organic amendments regulate soil enzyme activities and microbial nutrient limitations， thereby enriching the theoretical framework for aeolian sandy soil improvement. These findings provide a scientific basis and technical support for enhancing soil fertility and promoting sustainable agricultural development in aeolian sandy soil regions.