Agricultural nitrogen fertilizer use rate increased by 33 folds in the continental US during 1940-2015, with the hot-spots shifting from the west and southeast coast to the Midwest and the Great Plains.
The development of the Haber-Bosch process in the early 1900s led to the massive production of relatively cheap nitrogen fertilizer that boosted crop yields. While the inefficient management of synthetic nitrogen in agriculture(e.g. Application rate, Application timing, NH4-/NO3-) also increased the potential for nitrogen to be lost to the environment, which could lead to imbalance of nitrogen among atmospheric, terrestrial, and aquatic pools. Long-term and large-scale nitrogen management information is critical for assessing the increasing human-induced nitrogen issues and optimizing nitrogen management both economically and environmentally. Several digital maps based on the average nitrogen application rate of all crops for United States in recent decades have been developed. However, the application timing and fertilizer species with a longer period gained increasing attention due to their significant impact on the nitrogen lost. We applied multiple imputation methods to produce a new historical nitrogen fertilizer application rate map(1km ×1km) with application timing and NH4-/NO3- for the period 1850-2015 of Continental United States based on crop-specific information from United States Department of Agriculture (USDA) and various data sets.
Cao, P., C. Lu, and Z. Yu. 2018. Historical Nitrogen Fertilizer Use in Agricultural Ecosystem of the Continental United States during 1850–2015: Application rate, Timing, and Fertilizer Types. Earth System Science Data, 969-984. DOI:10.5194/essd-10-969-2018
Figure. Temporal pattern of nitrogen fertilizer use in the continental US.