Submitted to: International Conference on Precision Agriculture Abstracts & Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 7/20/1998
Publication Date: N/A
Interpretive Summary: Numerous procedures have been used to identify distinct within-field areas for site-specific management. Unfortunately, evaluation of the appropriateness of these management zones is seldom possible because most fields, once landscape and soil properties are measured and mapped, receive some type of site-specific management. Since misidentifying the appropriate management zones for a given operation or input may be no better than managing the field uniformly, the question of whether or not the appropriate management zones have been identified needs more scrutiny. From our research on a claypan soil field, we found that traditional soil surveys conducted by USDA-NRCS gave four different and contrasting soil maps. The order 2 soil survey (the order used for county surveys) was better than no sub-field delineation for developing crop yield relationships to soil nutrients. However, it was inferior when compared to oorder 1 soil surveys (soil survey at a scale that is five times more detailed than an order 2 survey). We concluded that it may be difficult to obtain repeatable results using soil survey. Determining management zones using more quantitative data, such as elevation and topsoil depth, may be more repeatable than the use of soil surveys. Zones determined by topsoil and elevation closely represented water-related soil differences in a field. The results of this study will benefit crop consultants and farmers by helping them develop improved site-specific management zones. NRCS personnel will also benefit by obtaining information on the effectiveness of soil survey in precision agriculture.
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 potassium, phosphorous, pH, and organic matter were determined in each zone for each method. Based on the number of significant positive correlations and the distribution of these correlations over the four soil-test parameters, one of the order 1 soil surveys and the quantitative method would be preferred for developing site-specific management plans. Because the quantitative method involves measurements that are repeatable, it may have an advantage over soil surveys. The order 2 soil survey (the level of soil survey generally available to farmers) was better than no sub-field delineation but was inferior when compared to the order 1 soil survey or quantitative method.