Soil Physical Properties and Soybean Yield as Influenced by Long-Term Tillage Systems and Cover Cropping in the Midsouth USA

A better understanding of the effect of long-term tillage management on soil properties and yield is essential for sustainable food production. This research aimed to evaluate the 37-year impact of different tillage systems and cover cropping on soil hydro-physical properties at 0-15 and 15-30 cm, as well as on soybean [Glycine max (L.) Merr] yield. The long-term experiment was located in Jackson, TN, and the different treatments involved in this study were no-tillage (NT), disk (DP), chisel (CP), moldboard plow (MP), and no-tillage with winter wheat [Triticum aestivum (L.)] cover crop (NTW). Forty-five days after the tillage operation, MP showed a comparable bulk density (BD) with NT, NTW, and CP at 0-15 cm depth. At surface depth, No-tillage systems increased cone penetration resistance (PR) by 12% compared with the reduced tillage systems, and 47% relative to MP. Wet aggregate stability (WAS) at surface depth was 27% and 36% greater for NT systems than for reduced and conventional tillage systems, respectively. Similarly, the geometric mean diameter (GMD) of aggregates was significantly higher under NT and NTW. However, water infiltration and field-saturated hydraulic conductivity (K-fs) did not differ significantly among tillage systems. The greatest soybean yield was obtained from CP and DP, producing 10% higher yield than NTW. Overall, 37 years of no-tillage, with or without simplified cover cropping did not result in a consistent improvement in soybean yield and soil physical properties with the exception of having improved soil aggregation.