Cover cropping and conservation tillage improve nutrient cycling and soil health in the southeastern USA

Authors: FARMAHA, BHUPINDER - Clemson University; SEKARAN, UDAYAKUMAR - Clemson University; Franzluebbers, Alan

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/17/2021
Publication Date: 2/24/2022
Citation: Farmaha, B., Sekaran, U., Franzluebbers, A.J. 2022. Cover cropping and conservation tillage improve nutrient cycling and soil health in the southeastern USA. Agronomy Journal. 114:296-316. https://doi.org/10.1002/agj2.20865.
DOI: https://doi.org/10.1002/agj2.20865

Interpretive Summary: Conservation agricultural systems have a long history of development and use in the southeastern United States, but they are still not the norm on the landscape. Literature from the region suggests that a diversity of soil properties can be improved with cover cropping and conservation tillage, but results are not always consistent. Our objectives were to (a) review recent research on conservation tillage and cover cropping in the region and (b) compile and synthesize recent data from a diversity of farms along a conventional to conservation gradient. As part of recent on-farm trials focused on soil N availability, we analyzed soil organic C and N fractions and routine soil nutrient characteristics from a total of 196 fields in corn (Zea mays L.), wheat (Triticum aestivum L.), and barley (Hordeum vulgare L.) production in three physiographic regions of the Coastal Plain (n = 71 fields), Piedmont (n = 77 fields), and Appalachians (n = 48 fields) in North Carolina, South Carolina, Pennsylvania, and Virginia. These data allowed us to establish first estimates of threshold optima for soil organic C and N fractions and other inorganic nutrients. On-farm data confirmed the literature review that conservation tillage resulted in greater stratification of soil organic C and N and nutrient concentrations. Soil health improvement could be inferred along the gradient from inversion tillage to no tillage without cover cropping to no tillage with cover cropping. This collection of recent literature and on-farm data can be a useful starting point for establishing target limits and assessing soil health conditions on farms in the region.

Technical Abstract: Conservation agricultural systems have a long history of development and use in the southeastern US, but they are still not the norm on the landscape. Literature from the region suggests that a wide diversity of soil properties can be improved with cover cropping and conservation tillage, but results are not always consistent. Our objectives were to review recent research on conservation tillage and cover cropping in the region and to compile and synthesize recent data from a diversity of farms along a conventional to conservation gradient. As part of recent on-farm trials focused on soil N availability, we analyzed soil organic C and N fractions and routine soil nutrient characteristics from a total of 196 fields in corn (Zea mays), wheat (Triticum aestivum), and barley (Hordeum vulgare) production in three physiographic regions of the Coastal Plain (n=71 fields), Piedmont (n=77 fields), and Appalachians (n=48 fields) in North Carolina, South Carolina, Pennsylvania, and Virginia. These data allowed us to establish first estimates of threshold optima for soil organic C and N fractions and other inorganic nutrients. On-farm data confirmed that conservation tillage resulted in greater stratification of soil organic C and N and nutrient concentrations. Soil health improvement could be inferred along the gradient from inversion tillage to no tillage without cover cropping to no tillage with cover cropping. This database can be a useful starting point for establishing target limits and assessing soil health conditions on farms in the region.