Short-Term Effects of Cover Crop Species and Termination Methods on Soil pH and Key Enzymatic Activities (β-Glucosidase, Phosphatase and Urease Activities) in a Citrus Orchard (Eureka Lemons)

The best management practices for cover cropping in citrus orchards, particularly in terms of species selection and termination methods, remain unclear. This study assessed the short-term effects of different cover crop species (vetch, medics and oats) and termination methods (slashed vs. non-slashed) on soil pH and enzyme activities (β-glucosidase, acid phosphatase, and urease) in a citrus orchard with sandy soil. A randomized complete block design with a factorial treatment structure and six replications was used. Soil samples were collected before and one year after cover crop establishment. The results showed that cover cropping increased soil pH from 5.42 to 6.00 after one year. However, no statistically significant differences were observed in soil pH or enzyme activities among cover crop species or termination methods. Marginal increases in enzyme activities were observed under leguminous cover crops, and these changes were insufficient to indicate strong treatment effects. Correlation and principal component analyses revealed that soil enzyme activities were more strongly influenced by soil properties (depth, carbon content and moisture) than by cover crop species or termination methods. These findings suggest that, under sandy soil conditions and within a one-year period, cover cropping has limited immediate effects on soil biological indicators in citrus orchards. Longer-term studies are recommended to assess cumulative impacts.