Long-Term Effects of Different Cropping Systems on Selected Enzyme Activities

The historic Sanborn Field located on University of Missouri campus at Columbia, Missouri, was designed to demonstrate the importance of agricultural practices, such as fertilization, tillage, and crop rotation. Knowledge of the effect of long-term agricultural practices on the soil quality is critical for farmers to make better management decisions to efficiently and sustainably produce crops. This study examined long-term fertilization, tillage, and crop rotation effects on the activities of soil enzymes including phenol oxidase, peroxidase, dehydrogenase, cellulose, and -glucosaminidase in the top soil layer (0-10cm). The results showed that pH, organic matter, and cation exchange capacity are important factors that are associated with enzyme activities. Compared to conventional tillage, no-tillage treatment significantly increased activities of phenol oxidase, peroxidase, dehydrogenase, and d -glucosaminidase. Fertilization increased cellulase and -glucosaminidase activity, but had mixed effects for phenol oxidase, peroxidase, and dehydrogenase depending on the type of fertilizer applied. The amount of nitrogen applied significantly affected soil enzyme activities. The influences of the crop type and rotation are significant but differ for each enzyme. Due to the sensitivity of soil enzymes to environmental factors, soil enzymes such as phenol oxidase, dehydrogenase, cellulose, and -glucosaminidase are suitable as indicators of soil quality.