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Cone Index before and after Plowing of Stony Clay Soil as a Function of Depth and Moisture

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.org

Citation:  2007 ASAE Annual Meeting  071129.(doi:10.13031/2013.23201)
Authors:   Amer (or initial) Najm, Moatasim M Sidahmed
Keywords:   Penetration resistance, Cone index, Prediction of cone index, Trafficability, clay soils, Soil strength, plowing

Cone index (CI), which is a measure of soil strength, is an essential parameter in studies related to site exploration, assessment of soil strength, prediction of workability and trafficability, and assessment of soil compaction and impedance to root penetration. However, the variation of CI with soil depth and moisture content in tilled and untilled soils is not yet well established. In this study, the effect of soil depth (D) and moisture content (MC) on mean cone index (CIM) before and after plowing was investigated on a stony clay soil using analysis of variance (ANOVA) and regression techniques. ANOVA was based on a split-plot design with three blocks representing different combinations of stubbles and percentages of stoniness, four levels of MC (6%, 12%, 18%, and 24% on wet basis) as main plots, and five levels of D (5, 10, 15, 20, 25, and 30 cm) as subplot. Results indicated that CIM was a function of D (Probability P<0.0001) before plowing, and a function of both MC (P=0.0353) and D (P<0.0001) after plowing. There was no D×MC interaction for either before or after plowing. Prediction equations for CIM were developed for both before plowing (coefficient of determination R2=0.744) and after plowing (R2=0.995) conditions, and a mathematical model (R2=0.991) relating before and after plowing CIM’s was developed (R2=0.991). Stones may have completely masked the effect of MC on CIM before plowing, and reduced the effect of MC on CIM after plowing.

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