Winter Wheat has been produced throughout the southern Great Plains for over 100 years.  In most cases this continuous production of mono-culture lower value wheat crop has led to the neglect of the soils, one such soil property is soil pH. In an area dominated by eroded soils and short term leases, Land-Grant University wheat breeders have created lines of winter wheat which are aluminum tolerant to increase production in low productive soils.  Now the fields in this region can have very high degree of variation in soil pH levels and available aluminum content.  Both of these aspects not only impact available phosphorus (P) levels but also the ability of phosphorus extraction methods to accurately determine plant available (P).  This work has three objectives. First, evaluate the infield variation in soil test parameters of fields that have been grid sampled.  Secondly, the impact of soil test pH on multiple soil test P extractants will be quantified. The first objective will be met by analyzing soil test results from 175 fields that have been sampled at a 1 to 2.8 hectare  resolution.  These fields will have been sampled by both Oklahoma State University researches and multiple private crop consultants. The second object will be met by utilizing six field trials previously established to evaluate the impact of soil pH and aluminum content on the grain yield of multiple crops.  At each location the soil pH was manipulated to result in a range of pH’s from 4.0 to 7.0.  Soil samples will be collected from each plot, 36 per location, each sample will be analyzed for base cation content and P content using Mehlich 3, water soluble extraction procedures. The final objective is to determine if average variation of infield soil pH will cause incorrect recommendations in a variable rate fertilizer application program. Given the trends in the data and the effect soil-pH appears to have on Mehlich-3 and water extractions, it seems unlikely that using a single soil extraction method on soils of varying pH would yield recommendations that are at the scale of accuracy needed by needed by VRT producers.