Characterization of soil pores in strip-tilled and conventionally-tilled soil using X-ray computed tomography

Authors: KAUR, PREETIKA - Auburn University; LAMBA, JASMEET - Auburn University; Way, Thomas - Tom; Balkcom, Kipling; SANZ-SAEZ, ALVARO - Auburn University; Watts, Dexter

Submitted to: Soil and Tillage Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/29/2023
Publication Date: 2/16/2024
Citation: Kaur, P., Lamba, J., Way, T.R., Balkcom, K.S., Sanz-Saez, A., Watts, D.B. 2024. Characterization of soil pores in strip-tilled and conventionally-tilled soil using X-ray computed tomography. Soil and Tillage Research. 239:106035. https://doi.org/10.1016/j.still.2024.106035.
DOI: https://doi.org/10.1016/j.still.2024.106035

Interpretive Summary: Strip tillage in agricultural row crops is a system with reduced tillage, compared to conventional tillage in which the complete soil surface is typically tilled. We investigated effects of conventional tillage (CT) and strip tillage (ST) on soil pore properties, to quantify changes in soil pore characteristics as a function of season. Undisturbed cylindrical soil cores (150 mm diameter and 500 mm length) were collected from a field in Alabama, planted with cotton under ST and CT treatments, in two seasons i.e., fall 2021 and spring 2022. Soil cores were collected from conventional tillage and strip tillage portions of the field, in the fall, following cotton harvest and before planting a cover crop (season 1), and the spring, after the cover crop had matured (season 2). X-ray computed tomography scans which are CT scans used in medicine, were used to quantify characteristics of pores in the soil. The ST treatment had significantly greater values of macroporosity, network density, macropore length density, and interconnectivity compared to the CT in season 1. CT is more prone to destruction of large macropores. This study shows that pore morphology is significantly affected by the choice of tillage practice and the seasonal aspects associated with the tillage practice. These results are expected to be useful in conducting computer modeling to retain nutrients in the crop root zone and in minimizing quality degradation of groundwater and water in streams, rivers, lakes, and other waterbodies.

Technical Abstract: Different factors, such as climate, soil type, and management practices, impact soil pore characteristics. Changes in the pore size distribution and connectivity can affect contaminant transport through the soil porous media. In recent years, conservation tillage practices, such as strip tillage have been promoted. However, limited information exists in the literature on the effect of strip tillage practices on soil pore characteristics. Thus, the objective of this research was to assess the effects of different tillage practices i.e., conventional tillage (CT) vs. strip tillage (ST), on soil pore properties and to quantify change in soil pore characteristics as a function of season. Undisturbed cylindrical soil columns (150 mm diameter and 500 mm length) were collected from a field in Alabama, USA planted with cotton (Gossypium hirsutum L.) under ST and CT treatments in two seasons i.e., fall 2021 and spring 2022. Soil cores were collected from conventional tillage and strip tillage portions of the field, in the fall, following cotton harvest and before planting a cover crop (season 1), and the spring, after the cover crop had matured (season 2). X-ray computed tomography was used to scan the soil cores and quantify soil pore characteristics. Results show that the ST treatment had significantly (p<0.05) greater values of macroporosity, network density, macropore length density, and interconnectivity compared to the CT in season 1. This is attributed to ST being a minimally disturbed treatment, having a better chance of preserving cracks and biological activity. CT is more prone to destruction of large macropores. The pore properties also showed a drastic decrease in values in season 2 especially for the top 200 mm of the soil profile in response to rainfall-induced soil reconsolidation. Overall, this study shows that pore morphology is significantly affected by the choice of tillage practice and the seasonal aspects associated with the tillage practice.