The effectiveness of management actions in reducing the release of excess nitrogen (N) to the environment is best assessed if N fluxes across air, land and water are regularly quantified at relevant scales. This dataset contains comprehensive 2002, 2007, and 2012 inventories of inputs and non-hydrologic N losses along with fossil fuel emissions, food demand, and terrestrial N surpluses for all HUC-8 subbasins of the contiguous United States using peer-reviewed, publicly available datasets.

,This data package was produced by researchers working on the Shortgrass Steppe Long Term Ecological Research (SGS-LTER) Project, administered at Colorado State University. Long-term datasets and background information (proposals, reports, photographs, etc.) on the SGS-LTER project are contained in a comprehensive project collection within the Digital Collections of Colorado (http://digitool.library.colostate.edu/R/?func=collections&collection_id=3429). The data table and associated metadata document, which is generated in Ecological Metadata Language, may be available through other repositories serving the ecological research community and represent components of the larger SGS-LTER project collection. Most investigators studying grasslands have assumed that the low standing biomass of the SGS created a system with a low probability of carrying fire, and thus a minimal historical role of fire. Nonetheless, there are years with aboveground biomass equivalent to the mixed grass prairie, and a high frequency of lightening storms. Regardless of the historical role of fire in SGS, there are new questions regarding its utility in managing for the presence of the threatened mountain plover, which only nests in areas of low plant biomass. United States Forest Service, Pawnee National Grassland recently initiated a burning program in the mid 1990s to address questions about using fire to increase plover habitat; we have collected data on some of these plots to investigate the influence of fire on SGS vegetation. Several datasets were created between 1999 and 2004 by SGS-LTER researchers, including measurements of shrub and cactus mortality rates, aboveground net primary production, amounts of litter and standing dead, and aboveground nitrogen dynamics in burned and control plots in the western section of the Pawnee National Grassland. Additional information and referenced materials can be found: http://hdl.handle.net/10217/83326.,,

Critical loads are a tool the NPS uses to assess and understand the impacts of nitrogen deposition to park ecosystems and help inform policy and management decisions to protect them. This analysis compares critical loads to the maximum level of nitrogen deposition (from the 2015–2017 average NADP Total Deposition model) present within a boundary. When the total deposition exceeds the critical load there is an increased risk of ecological harm. These critical loads (adapted from Pardo et. al 2011) are developed at the ecoregion scale and should only be used to evaluate risk. Where park specific or more recent critical loads exist, these should be used instead.

Human activities such as agricultural fertilization and fossil fuel combustion have introduced a massive amount of anthropogenic nitrogen (N) in reactive forms to the environment. As agricultural fertilization is the single largest anthropogenic N source, an integrated approach to understand the interactions among agriculture, atmosphere, and hydrology is essential in examining human-altered N cycling. We have developed an integrated modeling system with agriculture EPIC, atmosphere WRF/CMAQ, and hydrology SWAT. This integrated system is useful tool for scientists and policy-makers to answer many questions on cycling of water, carbon, and nutrients for sustaining the food production while protecting the environment. This dataset is associated with the following publication: Ran, L., Y. Yuan, E. Cooter, V. Benson, J. Pleim, R. Wang, and J. Williams. An Integrated Agriculture, Atmosphere, and Hydrology Modeling System for Ecosystem Assessments. Journal of Advances in Modeling Earth Systems. John Wiley & Sons, Inc., Hoboken, NJ, USA, 11(12): 4645-4668, (2019).

,This data package was produced by researchers working on the Shortgrass Steppe Long Term Ecological Research (SGS-LTER) Project, administered at Colorado State University. Long-term datasets and background information (proposals, reports, photographs, etc.) on the SGS-LTER project are contained in a comprehensive project collection within the Digital Collections of Colorado (http://digitool.library.colostate.edu/R/?func=collections&collection_id=3429). The data table and associated metadata document, which is generated in Ecological Metadata Language, may be available through other repositories serving the ecological research community and represent components of the larger SGS-LTER project collection. Most investigators studying grasslands have assumed that the low standing biomass of the SGS created a system with a low probability of carrying fire, and thus a minimal historical role of fire. Nonetheless, there are years with aboveground biomass equivalent to the mixed grass prairie, and a high frequency of lightening storms. Regardless of the historical role of fire in SGS, there are new questions regarding its utility in managing for the presence of the threatened mountain plover, which only nests in areas of low plant biomass. United States Forest Service, Pawnee National Grassland recently initiated a burning program in the mid 1990s to address questions about using fire to increase plover habitat; we have collected data on some of these plots to investigate the influence of fire on SGS vegetation. Several datasets were created between 1999 and 2004 by SGS-LTER researchers, including measurements of shrub and cactus mortality rates, aboveground net primary production, amounts of litter and standing dead, and aboveground nitrogen dynamics in burned and control plots in the western section of the Pawnee National Grassland. Additional information and referenced materials can be found: http://hdl.handle.net/10217/83326.,,

,This data package was produced by researchers working on the Shortgrass Steppe Long Term Ecological Research (SGS-LTER) Project, administered at Colorado State University. Long-term datasets and background information (proposals, reports, photographs, etc.) on the SGS-LTER project are contained in a comprehensive project collection within the Digital Collections of Colorado (http://digitool.library.colostate.edu/R/?func=collections&collection_id=3429). The data table and associated metadata document, which is generated in Ecological Metadata Language, may be available through other repositories serving the ecological research community and represent components of the larger SGS-LTER project collection. Additional information and referenced materials can be found: http://hdl.handle.net/10217/83462. Aboveground plant nitrogen dynamics monitoring consists of two separate data sets. a) Long-term peak-crop nitrogen concentrations have been sampled since 1983 annually from sites sampled for ANPP estimates across the CPER. Plots are clipped for ANPP in August each year and include moderately grazed sites in sections 24 and 25, ungrazed treatments at ESA and owl creek, coarse textured soils in owl creek, fine textured soils in section 25, as well as three catena topopositions in section 24. These datasets have been designed for monitoring and so it is advised to consider calcuating average based at the transect level. B) Seasonal dynamics of life-form (dominant grass, forb, shrub species) nitrogen concentrations were obtained from random grab samples of aboveground plant tissue are taken monthly from May-Aug. and in Oct., Dec., Feb., and April from 1983 – 2007 at sites where ANPP has been collected since 1983 (ESA, ridge, mid-slope and swale in section 24). The objectives are to assess annual/seasonal weather and site productivity/management with quantity and quality of forage and/or litter production. Combined, these two data sets also provide an estimate of nitrogen yield. These data can be linked with secondary producer data sets such as annual cattle weight gains, grasshopper abundance, small mammal monitoring, etc., to assess how forage/plant tissue quantity and quality drive population dynamics.,,

This tabular data set represents the mean rate of nitrogen from fertilizer and manure applied on agricultural land in 1997 compiled for two spatial components of the NHDPlus version 2 data suite (NHDPlusv2) for the conterminous United States; 1) individual reach catchments and 2) reach catchments accumulated upstream through the river network. This dataset can be linked to the NHDPlus version 2 data suite by the unique identifier COMID. The source data for mean rate of nitrogen from fertilizer and manure applied on agricultural land in 1997 was produced by Ruddy and others, (USGS, 2006). Units are kilogram per square kilometer. Reach catchment information characterizes data at the local scale. Reach catchments accumulated upstream through the river network characterizes cumulative upstream conditions. Network-accumulated values are computed using two methods, 1) divergence-routed and 2) total cumulative drainage area. Both approaches use a modified routing database to navigate the NHDPlus reach network to aggregate (accumulate) the metrics derived from the reach catchment scale. (Schwarz and Wieczorek, 2018).

This tabular data set represents the mean rate of nitrogen from fertilizer and manure applied on agricultural land in 1997 compiled for two spatial components of the NHDPlus version 2 data suite (NHDPlusv2) for the conterminous United States; 1) individual reach catchments and 2) reach catchments accumulated upstream through the river network. This dataset can be linked to the NHDPlus version 2 data suite by the unique identifier COMID. The source data for mean rate of nitrogen from fertilizer and manure applied on agricultural land in 1997 was produced by Ruddy and others, (USGS, 2006). Units are kilogram per square kilometer. Reach catchment information characterizes data at the local scale. Reach catchments accumulated upstream through the river network characterizes cumulative upstream conditions. Network-accumulated values are computed using two methods, 1) divergence-routed and 2) total cumulative drainage area. Both approaches use a modified routing database to navigate the NHDPlus reach network to aggregate (accumulate) the metrics derived from the reach catchment scale. (Schwarz and Wieczorek, 2018).

This tabular data set represents the mean rate of nitrogen from fertilizer and manure applied on agricultural land in 1997 compiled for two spatial components of the NHDPlus version 2 data suite (NHDPlusv2) for the conterminous United States; 1) individual reach catchments and 2) reach catchments accumulated upstream through the river network. This dataset can be linked to the NHDPlus version 2 data suite by the unique identifier COMID. The source data for mean rate of nitrogen from fertilizer and manure applied on agricultural land in 1997 was produced by Ruddy and others, (USGS, 2006). Units are kilogram per square kilometer. Reach catchment information characterizes data at the local scale. Reach catchments accumulated upstream through the river network characterizes cumulative upstream conditions. Network-accumulated values are computed using two methods, 1) divergence-routed and 2) total cumulative drainage area. Both approaches use a modified routing database to navigate the NHDPlus reach network to aggregate (accumulate) the metrics derived from the reach catchment scale. (Schwarz and Wieczorek, 2018).

,Nitrogen Source Study for Greenhouse gas Reduction through Agricultural Carbon Enhancement network in Fort Collins, Colorado Nitrogen fertilization is essential for optimizing crop yields; however, it increases N2O emissions. The study objective was to compare N2O emissions resulting from application of commercially available enhanced-effi ciency N fertilizers with emissions from conventional dry granular urea in irrigated cropping systems. These emissions were monitored from several irrigated cropping systems receiving N fertilizer rates ranging from 0-246 kg/ha from years 2007-2008 with intermediate rates of 157 kg/ha applied to the barley crop in corn-barley rotation and 56 kg/ha applied to the dry bens in the corn-dry bean rotation. Cropping systems included conventional-till continuous corn (CT-CC), no-till continuous corn (NT-CC), no-till corn–dry bean (NT-CDb), and no-till corn–barley (NT-CB). Nitrous oxide fluxes were measured during ten growing seasons using static, vented chambers and a gas chromatograph analyzer. This work shows that the use of no-till and enhanced-effi ciency N fertilizers can potentially reduce N2O emissions from irrigated systems.,