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Title: STRENGTH PROPERTIES AND ORGANIC CARBON OF SOILS IN THE NORTH APPALACHIAN REGION

Author
item BLANCO-CANQUI, H - OHIO STATE UNIVERSITY
item LAL, R - OHIO STATE UNIVERSITY
item Owens, Lloyd
item POST, W - OAK RIDGE NATIONAL LAB
item IZAURRALDE, R - UNIV. OF MARYLAND

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/20/2004
Publication Date: 5/2/2005
Citation: Blanco-Canqui, H.R., Lal, R., Owens, L.B., Post, W.M., Izaurralde, R.C. 2005. Strength properties and organic carbon of soils in the North Appalachian region. Soil Science Society of America Journal. 69:663-673.

Interpretive Summary: Soils have a wide variety of properties, and these properties influence how suitable soils may be for some uses. Soil strength, for example, is important in controlling plant growth, root development, and soil-moisture relationships. Soil strength is influenced by management practices and can be determined by measuring specific soil physical properties. A study in the north Appalachian region evaluated the impacts of different management practices on soil strength at different slope positions. Soils on the summit and foot slope positions were measured for compaction, bulk density, shear strength, water content, and soil organic carbon under conventional tillage, no-till with manure, no-till with no manure, disk with manure, forest, and pasture. Results show that slope position did not have much effect. Management, especially adding manure, had a large effect on soil strength and soil organic carbon. The information is useful to other research scientists and those who use soil properties to develop best management practices for producers.

Technical Abstract: Soil strength, influenced by management and soil properties,controls plant growth, root development, and soil-moisture relations. The impact of textural and structural parameters on soil strength is moderated by soil organic carbon (SOC) content. Therefore, the objectives of this study were to assess changes in soil strength and SOC content in watersheds under long-term (>10 yr) management practices in the north Appalachian region on a predominantly Typic Hapludults on undulating slopes (>6% slope). Seven watersheds under conventional tillage (CT), no-till with manure (NTm), no-till with no manure (NTnm), chisel plow, disk with manure (DiskM), forest, and pasture were studied. Cone index (CI), shear strength, bulk density, volumetric water content, and SOC content were determined at the summit, backslope, and footslope landscape positions at 0-100, 100-200, and 200-300 mm depths. The SOC content was slightly higher at footslope than at summit position in the cultivated watersheds. The bulk density was lower at footslope than at summit in NTm (1.22 vs. 1.42 Mg/m3) and chisel (1.34 vs. 1.47 Mg/m3) treatments. Forest had the lowest CI (0.19 MPa), shear strength (6.11 kPa), and bulk density (0.93 Mg/m3) and the highest SOC content (62.7 g/kg), whereas CT had the highest CI (0.67 MPa), shear strength (25.5 kPa), bulk density (1.44 Mg/m3), and the lowest SOC content (13.6 g/kg) in the 0-100 mm depth (P<0.01). The Ntm had higher SOC content (49.9 g/kg)than NTnm (30.0 g/kg), and both no-till treatments had lower bulk density (<1.21 Mg/m3) than CT (1.44 Mg/m3) at 0-100 mm depth (P<0.01). Manuring decreased both CI and shear strength, but increased SOC content. Shear strength and volumetric water content were the best predictors of CI; whereas SOC content, CI, volumetric water content were shear strength (r2 > 0.76; P<0.01). Results show that landscape positions had small effect, but management, particularly manuring, had large and significant effects on soil strength and SOC content.