Thank you for registering. Please read the following disclaimer.
The NuGIS Interactive Mapping interface is a companion product to an IPNI bulletin entitled A preliminary Nutrient Use Geographic Information System (NuGIS) for the U.S. The Bulletin contains the methods used to generate the data behind this interface and users are encouraged to review its content. Pages 41 and 42 of the Bulletin are especially important for users of this web tool as they explain the issues associated with county or watershed views of the nutrient balance data.
Two of the most important issues are:
1) Fertilizer sales data are in most cases used to represent fertilizer use. Since fertilizer could be applied in a county other than the one in which it is purchased, care should be used in interpreting high resolution data, especially the county data. Since watersheds contain data from multiple counties, they will generally be more reliable than the county view.
2)Crop removal is calculated at a county level for 21 crops. We estimate that these crops capture at least 90% of removal for 44 of the 48 states. The four states dropping below 90% are Arizona, California, Florida, and Georgia. Lettuce is the major missed crop for Arizona and wood for Georgia, while the nutrient removal and acreage of numerous crops are missed for California and Florida. Because of the spatial clustering of the numerous missed crops in California and Florida, county and watershed data are not currently available in this web tool. Adjustments are made at the state level such that the state contribution to national nutrient removal should be correct.
Also, county and watershed data are not currently available for Oregon and Maine due to unresolved issues with the nutrient balance data in several counties.
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