Agronomic Soil pH Recommendations Across the Conterminous United States

This dataset contains soil pH recommendations for the most commonly grown crop by land area in each county across the conterminous United States (CONUS). This dataset was created as part of a study by the authors listed here to estimate the amount of cropland in CONUS below optimal soil pH. We determined the cell counts of all crops in each county using the CroplandCROS (2022 dataset: https://croplandcros.scinet.usda.gov/). After completing these counts, we selected the highest value (the most common crop) for each county. The Grassland/Pasture pixel cell type from CroplandCROS was excluded from these counts due to differences in soil pH management practices compared to row crops. This process provided us with a list of the most spatially abundant crop grown in each county (n = 3,099). In each state, crop-specific soil pH recommendations are issued by a land-grant university agronomic extension agency. For each county, we recorded the state-specific soil pH recommendation for the most common crop. Often, agronomic extension agencies recommend a range, rather than an individual pH value (e.g., pH 5.5–5.8). When this was the case, we documented both the mean of the range (Average_Rec) and the maximum of the range (Maximum_Rec). There were 138 instances where we were unable to locate a crop-specific soil pH recommendation originating from the in-state agronomic extension. In these cases, the missing value was substituted by a recommendation from a different extension agency (either a neighboring state or high result from an internet search). In some states, multiple, conflicting soil pH recommendations were found for the same crop. In these cases, the more recently dated resource was selected. Extension agencies in several states, including Louisiana, Michigan, North Carolina, Tennessee, Wisconsin, and Wyoming recommend different pH values for crops grown in mineral and organic soils. For these states, a soils map was located and referenced to determine whether each county had all mineral soils, all organic soils, or a mixture of mineral and organic soils. In cases where a mixture existed, an unweighted average of the mineral and organic recommendations was recorded.