Quantifying short-term responsiveness and consistency of soil health parameters in row crop systems. Part 1: Developing a multivariate approach
Quantifying soil health requires measuring different physical, chemical and biological soil properties, yet limits in time and resources often restrict the number of parameters that can be analyzed. The main objective of this research was to identify soil health parameters that showed measurable and consistent responses to reduced tillage and cover cropping over a short (2-year) study period. In September 2015, four treatments – reduced tillage with cover crops, reduced tillage without cover crops, conventional tillage with cover crops and conventional tillage without cover crops – were installed in five sites across Virginia. Sites were managed for corn or tobacco production. Soils were analyzed for 32 properties associated with soil health, and cash crop yields were also measured in September 2016 and September 2017. A multivariate approach was used to detect treatment differences and determine parameters driving those differences. We then developed two new indices to quantify the responsiveness and consistency of soil health parameters. The results showed that surface soil layers had more parameters with significant differences between treatments than subsurface layers. Tillage effects were observed within 0.5 years, which may be due to the lack of tillage history in 4 of the 5 sites. Cover crop effects appeared after 1.5 years, indicating that this practice can also induce changes in soil properties over relatively short periods. Soil aggregate stability, potassium, calcium, magnesium, boron and cash crop yield were the most responsive parameters to reduced tillage and cover crop practices, while aggregate stability also showed high consistency. These findings suggest that aggregate stability effectively indicated short-term changes in soil health within row cropping systems of Virginia.