Enzyme Activity Variability and Comparison in Soils under Medicinal versus Crop Plants of Anguo City, China

Long-term continuous cultivation of different plant species in a similar agroecosystem intensively may result in divergent variability in soil fertility, particularly soil biochemical properties. In this study, an investigation was conducted to clarify the variability of five soil enzyme activities (urease, protease, catalase, polyphenol oxidase and alkaline phosphatase) of croplands under medicinal plants (herbal fields) and food crops (crop fields) in Anguo city, a traditional cultivation base for Chinese medicinal plants in China. The results showed that five soil enzyme activities were similar between herbal and crop fields. However, soil urease and alkaline phosphatase activities of herbal and crop fields decreased significantly with soil depth (0-60 cm), while protease, catalase, polyphenol oxidase activities were similar in all soil layers for two kinds of fields. There were largely variation scenes at linear correlation analysis between soil physicochemical traits and enzymatic activities under medicinal plant versus crop fileds although extensively significant correlations were presented. In conclusion, soil enzyme activities were similar in two type of farmlands, and soil urease and alkaline phosphatase activities decreased with soil depth for both fields. Inconsistent linear correlations between soil physicochemical traits and enzymatic activities under medicinal plant versus crop fields were presented, so soil enzymatic activity variation was subjected to soil physicochemical traits dominated by agronomic managements designed for specific plant species.