Soil physical properties and soybean yield as influenced by long-term tillage systems and cover cropping in the midsouth USA

Authors: NOURI, AMIN - University Of Tennessee; LEE, JAEHOON - University Of Tennessee; YIN, XINHUA - University Of Tennessee; TYLER, DONALD - University Of Tennessee; JAGADAMMA, SINDHU - University Of Tennessee; Arelli, Prakash

Submitted to: Sustainability
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/7/2018
Publication Date: 12/10/2018
Citation: Nouri, A., Lee, J., Yin, X., Tyler, D.D., Jagadamma, S., Arelli, P. 2018. Soil physical properties and soybean yield as influenced by long-term tillage systems and cover cropping in the midsouth USA. Sustainability. 10(12):4696. https://doi.org/10.3390/su10124696.
DOI: https://doi.org/10.3390/su10124696

Interpretive Summary: By 2050, agricultural food production is projected to increase by 70% globally in order to sustain food security for a growing population. Limited options to further expand global farmland area, necessitate the adoption of effective conservation practices to preserve the existing land currently available for cultivation. Conservation tillage is a recognized technique with the potential to increase agricultural sustainability by preserving soil and water resources and making production more economical. The effect of tillage systems on soil properties depends on the intensity of soil cultivation, amount and type of crop residue left after harvest and the placement of the residue within the soil profile. Soil structural properties are essential indicators of the soil’s ability to maintain its vital functions under cultivation. Maintaining those qualities is particularly important for rainfed cropping systems in humid climates such as the Mid-south region with torrential winter and spring rainfall and periodic droughts in summer. No-tillage is a leading conservation technique which has gained popularity, primarily due to its potential to reduce soil erosion and decrease production costs. Almost 35% of farmland in the U.S. and over 70% in Tennessee are managed under a no-tillage system. Most Tennessee upland soils are low in organic matter, prone to erosion and have poor water infiltration which all combine to increase the chance of crop failure. Despite the undisputed contribution of no-tillage to the reduction of soil loss, its positive effect on soil quality and crop yield is not consistent across farmland in the state. This research study was established in 1979 on the most representative soil type regionally, and is one of the ongoing long-term experiments in the Mid-south region studying five common tillage practices for soybean cropping systems. This study evaluated soil properties and soybean yield under long-term no-tillage, no-tillage with winter wheat cover crop and three tillage management systems, chisel plow, disk and moldboard plow. All were done under non-irrigated rainfed conditions in western Tennessee. Overall, 37 years using no-tillage techniques did not result in a consistent improvement in soybean yield or soil physical properties except for improving soil aggregation. Improving soil aggregation, the spaces (pores) between soil particles, provides spaces for retention and exchange of air and water.

Technical Abstract: A better understanding of the effect of long-term tillage management on soil properties and yield is essential for sustainable intensification of food production. This research evaluated the impact of 37 years of no-tillage (NT), disk (DP), chisel (CP) and moldboard plow (MP) and no-tillage with winter wheat [Triticum aestivum (L.) em. Thell.] cover crop (NTW) on soil hydro-physical properties and soybean [Glycine max (L.) Merr] yield in Jackson, Tennessee. Forty-five days after 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 to the reduced tillage systems and 47% relative to MP. Wet aggregate stability (WAS) at surface depth was 27% and 36% greater for NT and NTW compared with reduced and conventional tillage systems, respectively. Similarly, geometric mean diameter (GMD) of aggregates was significantly higher under NT and NTW. However, water infiltration and field-saturated hydraulic conductivity (Kfs) did not differ significantly among tillage systems. The greatest soybean yield was obtained from CP and DP, producing 10% higher yield than NTW. Overall, 35 years of no-tillage did not result in a consistent improvement in soybean yield or in soil physical properties with the exception that soil aggregation was improved.