Tillage Impacts on Depth Distribution of Total and Particulate Organic Matter in Three Illinois Soils

Summary

This field study examined how no-till versus conventional tillage practices affect the vertical distribution of soil organic matter and particulate organic matter in three fine-textured, poorly drained Illinois soils. No-till practices increased surface SOM-C and POM-C by 25% and 70% respectively, but this was accompanied by decreased carbon at depth (5–17.5 cm), with notable site-specific variation. The results suggest that the benefits of no-till for carbon accumulation depend on soil texture and drainage characteristics, with potential improvements to soil quality in erosion-prone silt loams but possible organic matter degradation in fine-textured silty clay loam soils.

Regional applicability

This study was conducted in central Illinois (United States) on soil types not typical of most United Kingdom farming regions. However, the methodological approach and findings on how tillage affects vertical organic matter distribution are transferable to UK arable farming, particularly for understanding trade-offs between surface carbon accumulation and subsurface carbon dynamics in clay-rich and poorly drained soils similar to those found in parts of eastern England.

Key measures

SOM-C concentration (%), POM-C concentration (%), bulk density, soil depth (0–5 cm, 5–17.5 cm, 5–30 cm), C and N sequestration on equivalent mass basis

Outcomes reported

The study measured soil organic carbon (SOM-C) and particulate organic matter (POM-C) contents at multiple soil depths (0–5 cm and 5–17.5 cm) under no-till versus conventional tillage practices across three soil types in Illinois. It assessed how tillage regime affected carbon distribution vertically through the soil profile and sequestration on an equivalent mass basis.

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