Harmonized land nutrient irrigation dataset (HLNID) for conterminous United States, 1938-2020

Land use-land cover, nutrient inputs from fertilizer and manure, and
irrigation are primary anthropogenic drivers of ecosystem functioning and
degradation. Historical datasets covering these drivers at various spatial
resolutions are essential for analyzing changes in these drivers as well
as for input to models that estimate ecosystem outcomes such as water
quality and runoff. We describe a new dataset for the conterminous United
States (CONUS) – the Harmonized Land Nutrient Irrigation Dataset (HLNID) –
that leverages existing datasets both at the county-scale (e.g., Census of
Agriculture) and higher resolution land change model outputs (e.g.,
FORE-SCE) and remotely-sensed products (e.g., NLCD, CDL) to produce annual
land use-land cover (including crop type), fertilizer and manure nutrient
mass (nitrogen and phosphorus), and irrigation extent for the years
1938-2020. The flexible method can provide data at a range of custom
spatial resolutions but we present results at 48 and 250 arc-seconds. The
dataset reveals specific changes such as the increase in corn and soybean
(replacing small grains and pasture) in the northern Great Plains since
the 1990s, the spatial concentration of manure production in certain
regions such as the uplands of the Southern Seaboard, and the expansion of
irrigation in regions such as the Prairie Gateway. The method can readily
incorporate new raw input datasets (e.g., CDL) to create updated versions
but is limited by current time lags in state fertilizer sales data
reporting.