Submitted to: International Soil Tillage Research Organization Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 7/3/2000
Publication Date: 7/3/2000
Citation: Raper, R.L., Schwab, E.B., Dabney, S.M. 2000. Site-specific measurement of site-specific compaction in the southeastern united states. Proceedings of the 15th International Soil Tillage Research Organization Conference. Ft. Worth, TX. July 3-7. Interpretive Summary: Root-limiting conditions resulting in reduced yields are commonplace in the Southeastern United States due to abundant soil compaction and limited rainfall during the growing season. An experiment has been conducted to determine the variation present in these root-restricting soil layers within several Southeastern fields. Using geostatistical methods to make predictions of the approximate distance between samples shows that in-row tillage may decrease natural field variability of soil compaction. The ability to model and predict the presence of the root- restricting layer is important because the use of site-specific tillage may be an appropriate alternative for site-specific compaction.
Technical Abstract: Yield variations are common in most fields in the Southeastern U.S. Increasing yields to maximum uniform levels by site-specific measurement and modification of nutrient levels have mostly been unsuccessful. Researchers are now recognizing the extreme variation in soil physical conditions that may be much more important than previously thought. Measurement and modification of site-specific soil physical conditions are now being attempted. Cone index measurements have been obtained for several soils in the Southeastern U.S. Most of these soils have an impervious layer that restricts root growth, particularly during periods of temporary drought that plague the Southeastern U.S., and require annual subsoiling for maximum yields. Measurements of cone index demonstrate the extreme variability in depth to the hardpan layer. Geostatistical models were successfully constructed for this data to predict the approximate distance between sampling points. Results from Upland soils showed that more variability may exist in the traffic and no-traffic middles than in the in-row position where tillage may have been extensively used. Similar distances between sampling points were also predicted for Coastal Plains soils.