|Tekeste, Mehari - UNIV. OF GEORGIA|
Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: July 25, 2004
Publication Date: July 25, 2004
Citation: Tekeste, M.Z., Raper, R.L., Schwab, E.B. 2004. Effects of soil drying on soil cone penetration resistance for norfolk sandy loam soils. In: Proceedings of the 7th International Conference on Precision Agriculture, July 25-28, 2004, Minneapolis, Minnesota. Interpretive Summary: The depth of compacted layers which restrict root growth in Southeastern U.S. soils varies greatly. A soil probe, the soil cone penetrometer, has been used to measure the depth of these root-restricting compacted layers. However, soil moisture, which can also vary widely within fields, affects the penetration resistance readings and the ability of the penetrometer to accurately sense the depth of the compacted layers. A study was conducted that found that soil drying increased the magnitude of soil compaction and decreased the predicted depth of the compacted layer. Increasing our ability to accurately predict the magnitude and location of this compacted layer may help to prescribe energy and cost friendly depth-specific tillage.
Technical Abstract: Site-specific detection of a soil hardpan is an important step in precision farming. Different methods have been developed including the ASAE standard soil cone penetrometer to detect the hardpan layer. Most of the newly developed methods use results obtained by a soil cone penetrometer as a reference to validate their potential. Soil factors, mainly soil moisture and bulk density, may influence the cone index measurement and the determination of the relative strength and depth of the hardpan layer. In this study, magnitude and location of soil hardpan were characterized by peak cone index, depth to the peak cone index and depth to the top of the hardpan layer. The effects of soil drying on peak cone index, depth to the peak cone index and depth to the top of the hardpan layer were studied for three compaction levels on a Norfolk Sandy Loam soil in a soil bin. The soil bin was wetted to near saturation and then subjected to four levels of soil drying. A multiple-probe-soil-cone-penetrometer was used to measure soil cone index. The results showed that soil drying had a significant effect on peak cone index for the single pass compaction (1.66 Mg m-3) but not for the double pass compaction (1.76 Mg m-3). A trend existed that showed that the predicted depth to the peak cone index and the top of the hardpan layer decreased with soil drying.