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United States Department of Agriculture

Agricultural Research Service

Title: An Evaluation of the Soil Conditioning Index in Semi-Arid Soils

Authors
item Zobeck, Teddy
item Wanjura, Donald
item Crownover, J - USDA-NRCS
item Robinson, C - WTAMU
item Green, C - TTU
item Bronson, K - TAMU

Submitted to: World Congress of Soil Science
Publication Type: Abstract Only
Publication Acceptance Date: January 30, 2002
Publication Date: April 14, 2002
Citation: ZOBECK, T.M., WANJURA, D.F., CROWNOVER, J., ROBINSON, C., GREEN, C., BRONSON, K.F 2002. AN EVALUATION OF THE SOIL CONDITIONING INDEX IN SEMI-ARID SOILS. 17TH WORLD CONGRESS OF SOIL SCIENCE Abstracts 3.883

Technical Abstract: The Soil Conditioning Index (SCI) has been proposed to predict the consequences of management actions on the state of soil organic carbon (SOC). The index was developed based on research in humid, temperate, loamy soils but has not been tested for many conditions. In this project, we determine the effects of management on SOC in semiarid, thermic, sandy soils. Study sites were located in the Southern High Plains of west Texas where long term native range or grassland were adjacent to cropped land. Three replications were sampled on each treatment. Each replication was sampled at five depths to 60 cm. Carbon was measured with a CN analyzer and bulk density was used to calculate the carbon on a mass basis. Systems included native range, conservation grassland, cotton, wheat, wheat cotton rotation, sorghum, high residue sorghum/forages, sunflowers, and black eyed peas. The cropland included dryland and irrigated crops. Cropping reduced SOC significantly and only the surface five cm depth was enriched in SOC even after long term growth of conservation grassland in this study. Significant differences in SOC for the surface layer were in the order Native Range (NR)>Conservation Grassland (CG)>Cropland (CL). In most other depth layers the NR was greater than the CG and CL, which were the same. SOC differences with depth were only found in the native range sites with the surface layer having about 40% more SOC than the other layers. Overall, significant decreases in SOC were observed by surface texture in the order loam>fine sandy loam>loamy fine sand = fine sand.

Last Modified: 10/30/2014
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