Datasets

Description:

This dataset contains catchment-level estimates of nitrogen and phosphorus fertilizer use, for agricultural lands, for the conterminous U.S., for 2012. An approach was developed to relate farm commercial fertilizer sales data from the Association of American Plant Food Control Officials (AAPFCO) to a set of explanatory variables using spatially-referenced modeling methods. Separate models for nitrogen and phosphorus are developed to estimate elemental fertilizer use on agricultural lands for the conterminous U.S. at the National Hydrography Dataset Plus version 2 (NHDPlusV2) catchment scale. The approach builds on earlier efforts that use Association of American Plant Food Control Officials (AAPFCO) data on fertilizer sales to provide county-level estimates of nitrogen and phosphorus fertilizer use. The spatially-referenced method improves on these efforts by allowing for varying nitrogen to phosphorus (NP) ratios at the catchment scale and expanding the set of variables used to allocate county-level sales data to the catchment scale. The models include catchment-level factors that are either primary determinants of fertilizer use, such as the acreage of different crop types, or measures reflecting the intensity of use, such as climate. Explanatory variables available only at the county scale, such as United States Department of Agriculture (USDA) Census of Agriculture (COA) estimates of fertilizer expenditures, are included to improve the model predictions of elemental use. The nitrogen and phosphorus models explain over 90 percent of the variation in elemental use, and the statistical approach allows for the estimation of uncertainty of predicted use in each catchment. The spatial patterns of model estimates reflect known agricultural cropping practices across the U.S. that transcends political boundaries, despite the county/state-orientation of the fertilizer sales information. The results are expected to be useful for a variety of water-quality assessments that are intended to estimate nitrogen and phosphorus loads to streams. A companion data release provides catchment/county level model input for the nitrogen and phosphorus fertilizer use models and is listed in this metadata under Cross Reference. The software and methods used for producing these estimates are described in the USGS Scientific Investigations Report 2018-5145 (please see documentation link).

Citation:

Stewart, J.S., Schwarz, G.E., Brakebill, J.W., and Preston, S.D., 2019, Catchment-Level Predictions of Nitrogen and Phosphorus Fertilizer Use from Commercial Fertilizer Sales Data for the Conterminous U.S., 2012: U.S. Geological Survey data release, https://doi.org/10.5066/F7CZ36F4

Additional Information: