This dataset includes all of the variables that were used in predictive models to estimate nitrogen and phosphorus fertilizer use from commercial fertilizer sales data at the catchment/county level for the Conterminous U.S. for the year 2012. The dataset includes model input at the catchment/county level. A companion USGS Scientific Investigations Report describes the methods and subsequent results of two models developed for estimating elemental nitrogen and phosphorus commercial fertilizer use on agricultural lands for the conterminous US at the catchment/county scale for the year 2012. A companion data release provides catchment-level estimates of nitrogen and phosphorus fertilizer use, for agricultural lands, for the Conterminous U.S., for 2012. The software and methods used for producing this dataset are described in the USGS Scientific Investigations Report listed in this metadata under Larger Work Citation.

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 listed in this metadata under Larger Work Citation.

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 listed in this metadata under Larger Work Citation.

This data set contains county-level estimates of nitrogen and phosphorus from fertilizer, for both farm and nonfarm uses, for the conterminous United States, for 1987 through 2006. State-level farm and nonfarm nitrogen and phosphorus were derived from the Association of American Plant Food Control Officials (AAPFCO) commercial fertilizer sales data. State estimates were then allocated to the county-level using fertilizer expenditure as county weights for farm fertilizer, and population density as county weights for nonfarm fertilizer.

This data set contains county-level estimates of nitrogen and phosphorus from fertilizer, for both farm and nonfarm uses, for the conterminous United States, for 1987 through 2006. State-level farm and nonfarm nitrogen and phosphorus were derived from the Association of American Plant Food Control Officials (AAPFCO) commercial fertilizer sales data. State estimates were then allocated to the county-level using fertilizer expenditure as county weights for farm fertilizer, and population density as county weights for nonfarm fertilizer.

This data set contains county-level estimates of nitrogen and phosphorus from fertilizer, for both farm and nonfarm uses, for the conterminous United States, for 1987 through 2006. State-level farm and nonfarm nitrogen and phosphorus were derived from the Association of American Plant Food Control Officials (AAPFCO) commercial fertilizer sales data. State estimates were then allocated to the county-level using fertilizer expenditure as county weights for farm fertilizer, and population density as county weights for nonfarm fertilizer.

This data set contains county-level estimates of nitrogen and phosphorus from fertilizer, for both farm and nonfarm uses, for the conterminous United States, for 1987 through 2012. State-level farm and nonfarm nitrogen and phosphorus were derived from the Association of American Plant Food Control Officials (AAPFCO) commercial fertilizer sales data. State estimates were then allocated to the county-level using fertilizer expenditure from the Census of Agriculture as county weights for farm fertilizer, and effective population density as county weights for nonfarm fertilizer. Data computations for 2007 - 2012 estimates are results of methods applied directly from Gronberg and Spahr, 2012. Data for 1987 - 2006 are exactly those published in Gronberg and Spahr, 2012.

This data set contains county-level estimates of nitrogen and phosphorus from fertilizer, for both farm and nonfarm uses, for the conterminous United States, for 1987 through 2012. State-level farm and nonfarm nitrogen and phosphorus were derived from the Association of American Plant Food Control Officials (AAPFCO) commercial fertilizer sales data. State estimates were then allocated to the county-level using fertilizer expenditure from the Census of Agriculture as county weights for farm fertilizer, and effective population density as county weights for nonfarm fertilizer. Data computations for 2007 - 2012 estimates are results of methods applied directly from Gronberg and Spahr, 2012. Data for 1987 - 2006 are exactly those published in Gronberg and Spahr, 2012.

Estimated seasonal total nitrogen and total phosphorus loads during 1999 through 2020 in selected streams of the conterminous United States and water-quality and stream flow data used to generate those estimates are presented in this dataset. Loads were generated as part of the Integrated Water-Availability Assessment (IWAA) Program of the U.S. Geological Survey (www.usgs.gov/mission-areas/water-resources/science/integrated-water-availability-assessments#overview) using Fluxmaster (Schwarz and others, 2006, https://doi.org/10.3133/tm6B3) and Weighted Regression on Time, Discharge, and Season (WRTDS) (Hirsch and De Cicco, 2015, https://doi.org/10.1016/j.envsoft.2015.07.017). Loads were estimated initially for the Illinois River Basin (IRB) and later for the wider conterminous United States (including the IRB). Along with the water-quality data, streamflow data, and estimated nitrogen and phosphorus loads, this release also includes computer code that can be run to recreate the load estimates or modified for similar applications.

Estimated seasonal total nitrogen and total phosphorus loads during 1999 through 2020 in selected streams of the conterminous United States and water-quality and stream flow data used to generate those estimates are presented in this dataset. Loads were generated as part of the Integrated Water-Availability Assessment (IWAA) Program of the U.S. Geological Survey (www.usgs.gov/mission-areas/water-resources/science/integrated-water-availability-assessments#overview) using Fluxmaster (Schwarz and others, 2006, https://doi.org/10.3133/tm6B3) and Weighted Regression on Time, Discharge, and Season (WRTDS) (Hirsch and De Cicco, 2015, https://doi.org/10.1016/j.envsoft.2015.07.017). Loads were estimated initially for the Illinois River Basin (IRB) and later for the wider conterminous United States (including the IRB). Along with the water-quality data, streamflow data, and estimated nitrogen and phosphorus loads, this release also includes computer code that can be run to recreate the load estimates or modified for similar applications.