Influence of Tillage on Aggregate Stability in Clay Soils of North Texas

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Ag Science and Natural Resources

Date of Award

8-14-2024

Abstract

Soil management practices have drastic effects on soil overall health, particularly tillage. Tillage and cover crops can influence a multitude of soil physical properties. One measurable property is aggregate stability, which is commonly considered an indicator of soil quality, erosion potential, and water infiltration. Two studies were conducted at the Texas A&M University Greenville Research, Extension, and Teaching Farm to investigate the aggregate stability of clay soils. One study investigated soils under various tillage regimes (no-till, vertical till, and strip-till) implemented over four years. The second study evaluated soils under one year of cover crop (hayed, controlled with herbicide, or bare ground). Soil samples were collected from each study and processed according to methods developed by Yoder (1936) and modified by Kemper and Rosenau (1986) and Garcia et al. (2022) to determine the amount of stable aggregates and the distribution of aggregate by size (<1 mm, 1-2 mm, and >2 mm). No differences in aggregate stability were found among tillage or cover crop treatments. Differences were noted in 1-2 mm and <1 mm aggregates for the May 2024 sampling in the tillage study. Bi-annual vertical tillage had the most 1-2 mm aggregates, and no-till and annual vertical tillage had the least. For <1 mm aggregates, no-till, and annual vertical tillage had the most, and bi-annual vertical tillage had the least. While these differences in aggregate size suggest that tillage does have an influence on aggregate size, this effect did not translate to a difference in aggregate stability, which is directly related to soil health. The results of this study indicate that the influence of tillage and cover crops on aggregate stability and overall soil health is less pronounced in heavy clay soils than in other soils in well-studied, agronomically important regions.

Advisor

Grace Flusche Ogden

Subject Categories

Earth Sciences | Physical Sciences and Mathematics | Soil Science

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