Submitted to: North Central Extension Industry Soil Fertility Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: November 12, 1998
Publication Date: N/A
Technical Abstract: Within-field management zones should represent unique combinations of potential yield-limiting factors for which we can develop improved site specific management prescriptions. Unfortunately, the procedures for identifying these management zones have not been well established. Two soil survey methods (Order 1 and Order 2 surveys) and a quantitative method d(soils classed by topsoil depth and elevation) were used to identify water related soil/landscape management zones on a 36-ha claypan soil field located near Centralia, Missouri. Linear correlation coefficients between yield and soil-test K, P, pH, and organic matter were determined in each zone for each method. To compare the utility of the various management-zone methods in representing variability, area-weighted correlation coefficient were calculated for each zone and then summed to give a rating score for each method-soil parameters combination. The highest rating for any given soil-test parameter came from the Order 1 soil surveys. The quantitative method using topsoil depth and elevation performed approximately equal to the Order II soil survey. Ratings for drier years and/or years with corn or grain sorghum tended to be higher than those for wet years and/or with soybean. Using this procedure to test these various management-zone methods, no one method was clearly better than the rest. Correlations were generally higher with management-zone methods distinguishing small sub field areas, but these areas also contained fewer cells usable for the correlation analysis. Overall, order I soil surveys gave the best results, but the improvements were not dramatic. On the other hand, because the quantitative method uses automated measurements that are georeferenced, it has the advantage of being repeatable.