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ARS Home » Plains Area » Lubbock, Texas » Cropping Systems Research Laboratory » Wind Erosion and Water Conservation Research » Research » Publications at this Location » Publication #306478
Title: Soil quality index comparisons using Fort Cobb Oklahoma watershed-scale land management data

Author
item Zobeck, Teddy
item Steiner, Jean
item Stott, Diane
item Duke, Sara
item Starks, Patrick
item Moriasi, Daniel
item Karlen, Douglas

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/24/2014
Publication Date: 1/13/2015
Publication URL: http://handle.nal.usda.gov/10113/60623
Citation: Zobeck, T.M., Steiner, J.L., Stott, D.E., Duke, S.E., Starks, P.J., Moriasi, D.N., Karlen, D.L. 2015. Soil quality index comparisons using Fort Cobb, Oklahoma, watershed-scale land management data. Soil Science Society of America Journal. 79(1):224-238.

Interpretive Summary: Two different but related methods for evaluating soil management effects on soil quality are called the Soil Conditioning Index (SCI) and Soil Management Assessment Framework (SMAF). Although both tools have been widely used, little is known regarding how they compare to one another and if they produce similar evaluations when comparing the same agricultural management systems. This study evaluates the SCI and SMAF by comparing and contrasting soil quality assessments as represented by the SMAF soil quality index (SQI) with a similar soil quality index provided by SCI for the Fort Cobb Reservoir Experimental Watershed (FCREW) in Oklahoma. Forty-one loamy and sandy surface soil sites were sampled on the FCREW to represent a range of agricultural land management systems that included conventionally-tilled annual cropping (CNL), conservation or no-till annual cropping (CSR), conversion of cropland to perennial grass (CVR), and native grass (NAT). Results show SMAF and SCI values both gave the same general result, indicating that soil quality within CNL and CSR systems were the same but of lower quality compared to CVR and NAT grassland systems that were generally similar. In comparisons of soil properties by texture class, surface soil texture alone generally had no effect on soil quality indicators in this study. Test of the relationships between SCI and various SMAF variables showed that a measure of how easily the soil is disrupted by rainfall, the soil organic matter, and a measure of microbial activity were related with SCI in CNL systems but none of the SMAF variables were correlated with SCI in the CVR and NAT systems. These results suggest that for this region, SMAF and SCI tests are related in tilled systems with limited residue cover but they are not related for no-tillage systems in pasture/grassland that has been in place for at least 10 years.

Technical Abstract: The Soil Conditioning Index (SCI) and Soil Management Assessment Framework (SMAF) are two different but complementary methods for evaluating soil management effects on soil quality. Although both tools have been widely used, little is known regarding how they compare to one another and if they produce similar evaluations when comparing the same agricultural management systems. This study evaluates the SCI and SMAF by comparing and contrasting soil quality assessments as represented by the SMAF soil quality index (SQI) with that provided by SCI for the Fort Cobb Reservoir Experimental Watershed (FCREW) in Oklahoma. Forty-one loamy and sandy surface soil sites were sampled on the FCREW to represent a range of agricultural land management systems that included conventionally-tilled annual cropping (CNL), conservation or no-till annual cropping (CSR), conversion of cropland to perennial grass (CVR), and native grass (NAT). Results show SMAF SQI and SCI values both gave the same general result, indicating that soil quality within CNL and CSR systems were the same but of lower quality compared to CVR and NAT grassland systems that were generally similar. In comparisons of soil properties by texture class, surface soil texture alone generally had no significant effects on soil quality indicators in this study. Correlations between SCI and various SMAF indicators or indicator scores showed that wet aggregate stability (WAS), soil organic carbon (SOC), and the ß-glucosidase activity (BGA) scores were positively correlated with SCI in CNL systems but none of the SMAF indicators or scores were correlated with SCI in the CVR and NAT systems. These results suggest that for this region, SMAF and SCI indicators and scores are correlated in tilled systems with limited residue cover but they are not correlated for no-tillage systems in pasture/grassland that has been in place for at least 10 years.