Effects of yak dung and urine deposition on the hydrolytic enzyme activities of an alpine grassland soil

To investigate the effects of yak dung and urine deposition on the soil hydrolytic enzyme activities in an alpine grassland, four treatments, including a control (CK), urine (UE), dung (DE), and dung plus urine (UDE) were set up to simulate different behaviors of yak excretion, soil physicochemical properties, microbial biomass carbon, and nitrogen concentrations, and hydrolytic enzyme activities were simultaneously measured. The results showed that excreta deposition did not affect soil microbial biomass carbon (MBC) and microbial biomass nitrogen (MBN) concentrations. Urine deposition inhibited soil urease (UA) and sucrase (SA) activities and enhanced leucine aminopeptidase (LAP) activity, but had no significant effect on β-1,4-xylosidase (BX) activity (P > 0.05). DE promoted soil LAP activity, inhibited SA and BX activities, but did not affect UA activity. UDE inhibited soil UA, LAP, SA, and BX activities. Redundancy analysis showed that NH ₄⁺-N and pH were the main environmental factors driving soil enzyme activities.