Texture and organic matter associations with soil functional properties in crop and conservation land uses in North Carolina

Authors: Franzluebbers, Alan

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/11/2023
Publication Date: 3/1/2024
Citation: Franzluebbers, A.J. 2024. Texture and organic matter associations with soil functional properties in crop and conservation land uses in North Carolina. Soil Science Society of America Journal. 88(2):449-464. https://doi.org/10.1002/saj2.20620.
DOI: https://doi.org/10.1002/saj2.20620

Interpretive Summary: Soil health evaluations may benefit from associations of simply determined metrics with more complicated properties and processes. Soil texture and organic matter are two overarching factors that control many other soil properties, and particularly their susceptibility for change with conservation management. A scientist in Raleigh, North Carolina evaluated the associations between soil physical, chemical, and biogeochemical properties and processes under conventional-till cropland, no-till cropland, grassland, and woodland across four physiographic regions in North Carolina. Both sand concentration and total soil nitrogen concentration formed strong associations with other soil properties. Sieved soil density was a strong integrative property of both sand and total soil nitrogen concentrations. Sieved soil density was a strong indicator of soil physical and biogeochemical conditions, including soil water and carbon storage. These results will be useful for scientists and agricultural advisors to help farmers understand the impacts of management on soil health conditions in the eastern US.

Technical Abstract: Soil texture and organic matter are considered overarching factors controlling a diversity of soil processes and properties. However, a more complete understanding of how these factors quantitatively affect other soil properties has been lacking due to either limited scope of land use and management conditions, confounding climate and environmental conditions with management, or narrow range of soil and management conditions. This study evaluated the strength of associations of sand and total soil N concentrations with soil physical, chemical, and biological properties and processes from 310 surface-soil (0–10-cm depth) samples (87% Ultisols, 4% Inceptisols, and less than or equal to 3% each of Alfisols, Spodosols, Entisols, and Histosols) collected under conventional-till and no-till cropland, grassland, and woodland in four physiographic regions of North Carolina. Sand concentration was most strongly associated with dry-stable mean-weight diameter (MWD), MWD product, and sieved soil density (|r| > 0.63, p < 0.001). Total soil N concentration was most strongly associated with particulate organic C and N and soil water content at water-holding capacity (|r| > 0.74, p < 0.001). Soils under unfertilized woodlands deviated the most from general associations, suggesting that organic matter quality could be unique, and requires further investigation. Overall, sand concentration associated more closely with soil physical properties and total soil N concentration associated closely with both soil physical and biogeochemical properties. Soil chemical properties were only weakly associated with either property. This study suggests that soil texture and organic matter would be complementary, additional properties in holistic soil health assessments that already included routine soil chemical analyses.