Soil strength after 21 years of conventional and organic cropping practices in the Mid-Atlantic region, USA

Authors: Schomberg, Harry; Balkcom, Kipling; Cavigelli, Michel; White, Kathryn

Submitted to: Soil and Tillage Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/9/2025
Publication Date: 12/11/2025
Citation: Schomberg, H.H., Balkcom, K.S., Cavigelli, M.A., White, K.E. 2025. Soil strength after 21 years of conventional and organic cropping practices in the Mid-Atlantic region, USA. Soil and Tillage Research. 258. Article e107020. https://doi.org/10.1016/j.still.2025.107020.
DOI: https://doi.org/10.1016/j.still.2025.107020

Interpretive Summary: Soil compaction is a concern for producers because it negatively impacts water and nutrient availability and can negatively impact crop yields. Organic and conventional production systems use different methods for weed control (frequent tillage vs herbicides) and sources of nutrients (organic vs inorganic) which can result in differences in soil compaction. We measured soil compaction in the long-term (17 years) Farming Systems Project (FSP) at the Beltsville Agricultural Research Center in Beltsville, MD. The FSP has five management systems laid out so that each phase of a rotation is present every year. The two conventional systems, No-tillage (NT) or Chisel Tillage (CT), are 3-yr corn–soybean–wheat rotations and use chemical fertilizers and chemical weed control. The organic rotations are: 2-yr corn–soybean (Org2); 3-yr corn–soybean–wheat (Org3); and 6-yr corn–soybean–wheat–alfalfa–alfalfa–alfalfa (Org6) and depend on frequent tillage for weed control and organic inputs for nutrients. Soil compaction measured from 0 to 20” prior to corn planting was less in Org2 and Org3 in the top 6” compared to other systems. This was a residual effect of frequent shallow tillage for weed control during the previous cropping season. Below 6”, soil compaction was less in the NT system compared to the other systems indicating that long-term use of NT can produce beneficial changes in soil structure. These changes can increase the ability of plant roots to capture water and nutrients, leading to the potential for increased yields. Crop consultants and extension agents will use this information to recommend no-tillage practices to farmers to reduce soil compaction and improve yield.

Technical Abstract: Soil compaction negatively impacts soil physical properties and crop yields and is influenced by organic matter inputs and tillage management. We evaluated cone index (CI) in five long-term organic and conventional cropping systems at the Farming Systems Project in Beltsville, MD (39.0°N, 76.9°W), to understand how different management systems influence soil strength. Measurements were collected prior to planting corn in 2017 using a tractor-mounted hydraulic five-probe penetrometer for three depths (0–15, 15–30, 30–50'cm) and three positions relative to the crop row (0, 22.5, and 45'cm). The two conventional systems, No-till (NT) and Chisel Till (CT), were both 3-yr corn-rye cover crop/soybean–wheat/soybean rotations. The three organic systems were comprised of: (Org2) 2-yr hairy vetch cover crop/corn-rye cover crop/soybean; (Org3) 3-yr hairy vetch cover crop/corn-rye cover crop/soybean–wheat; and (Org6) 6-yr corn-rye cover crop/soybean–wheat–alfalfa–alfalfa–alfalfa. Org2 and Org3 exhibited the lowest CI in the 0–15'cm depth, due to fall tillage before cover crop planting and weed control in the prior crop. In contrast, surface soil compaction in Org6 was similar to that in the conventional systems, attributed to alfalfa harvest machinery traffic over the past three years and absence of any tillage. At deeper depths (15–30'cm and 30–50'cm), the NT system consistently demonstrated lower CI compared to other systems. For tilled systems, maximum CI values at 15–30'cm were near or exceeded the root-restricting threshold of 2.5'MPa. The NT system potentially provided a larger rooting volume for water and nutrient uptake than tilled systems. Machinery traffic increased compaction, particularly at 22.5'cm from the crop row, likely due to tire sidewall pressure. Overall, the study found moderate effects of contrasting management system practices on soil strength.