Soil Health Is Not Distinguished Under Long-Term Cropping Systems in North Carolina Soils.

Soil productivity varies across regions, climates, and soil types. New soil tests were developed that evaluate ‘soil health’ conditions on a universal scale, but they have not been assessed in regionally unique soil conditions. The objective of this work was to evaluate three soil tests in North Carolina. We used long-term trials with different agronomic management in three regions: mountain (20 yr), piedmont (30 yr) and coastal plain (16 yr). These trials were originally established to determine the effect of management systems on soil properties and corn and soybean yields. Mountain and coastal plain trials included combinations of organic or conventional production within conventional, reduced, or no tillage systems, whereas the piedmont trial included nine tillage systems using moldboard, chisel, disk, subsoiling, or no-till equipment. Soil samples were collected and submitted for analysis as recommended by the North Carolina Department of Agriculture and Consumer Services (NCDA&CS), Haney, and Cornell Soil Health (CSH) labs. Each soil test indicated that plant nutrients were variable across treatments, but sufficient on average for most treatments. The Haney test recommended greater amounts of fertilizer than NCDA&CS, and the pH of CSH analyses was approximately 20% less than NCDA&CS analyses. Physical soil indicators on the CSH soil test were not significantly different regardless of tillage intensity. Only biological CSH soil indicators were significantly different between treatments, with, active carbon, and soil protein content being greatest in no-till systems. Overall CSH scores were low to very low for all treatments. Haney soil health scores were variable in the mountain trial, but 100% greater in no-till than conventional tillage in the piedmont trial. Despite soil health testing rarely distinguishing between management systems, conventionally managed no-till treatments generally had the greatest yields, and current soil health tests may not be configured to detect the most influential soil properties.