Soil Enzyme Activities Associated with Differential Outcomes of Contrasting Approaches to Soil Fertility Management in Corn and Soybean Fields

Sustainable agricultural practices such as reduced tillage and optimized fertilization may have potential to improve soil health and increase availability of plant nutrients and yields. However, there is very little information relating soil quality or health to crop productivity, particularly under farmer management. Therefore, the objective was to investigate the effects of two contrasting approaches to crop fertility management on crop productivity, soil test measurements, and soil enzyme activity as integrative measures of soil health. A three year study was conducted at on-farm sites in Ohio, Illinois, and Iowa where topsoil (0-15 cm) and crop yield of Zea mays L. (corn) and Glycine max. (L.) Merr. (soybean) rotations were collected from two contrasting fertility management systems. The two contrasting approaches tested were the Maximum Farming System (MFSyst) and a more Conventional system (Conv) that differ in approaches to tillage and the frequency of fertilizer applications during the growing season. The MFSyst approach resulted in significantly higher yields, soil nutrient test levels along with β-glucosidase (GLU) and arylsulfatase (ARYL) which are sensitive soil health indicators. Nitrogen use efficiency (NUE) of corn was significantly elevated by nearly 18%, corn yield correlated with GLU activities, and soil test phosphorous (P) levels were reduced by over 50% using the MFSyst approach. These results indicate that improvements in soil health detected by soil GLU and ARYL enzyme activities are associated with significant improvements in soil quality and crop productivity.