Supplementary data for: Global Gridded Nitrogen Indicators: Influence of Crop Maps

Kaltenegger, K. ORCID: https://orcid.org/0000-0001-7751-7794 (2020). Supplementary data for: Global Gridded Nitrogen Indicators: Influence of Crop Maps. 10.22022/air/10-2020.109.

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Abstract

Displaying Nitrogen (N) indicators on a global grid poses unique opportunities to quantify environmental impacts from N application in different world regions under a variety of conditions. Such calculations require the use of maps showing the geo-spatial distribution of crop production. Although there are several crop maps in the scientific literature to choose from, the consequences of this choice for the calculation of N indicators still need to be evaluated. In this study we analyze the differences in results for NUE and N surplus calculated on the global scale using two different crop maps (SPAM and M3). For our calculations we used publicly available statistical and literature data combined with each crop map and carefully traced the origins of the differences in the results. Our results showed that the regions most affected by discrepancies caused by differences in crop maps (yields and physical area) are Central Asia and the Russian Federation, Australia and Oceania, and North Africa. However, we also found that the inclusion or exclusion of grass crops influences the results, as does the aggregation of crops to categories. Considering all these differences, we note that M3 seems to provide the more plausible results for the calculation of N indicators. Our analysis not only highlights the importance of determining the critical parameters for N indicator calculation, but also allows key parameters connected with N use and overuse to be identified on the global scale. This dataset contains: All gridded N input and output data (provided in netCDF format and includes a description of the calculation) Gridded results of N surplus based on SPAM and M3 (provided in netCDF format and includes a description of the calculation) NUE per country (comparison of data by Leip et al., 2009, Lassaletta et al., 2014 and variations of our SPAM and M3 based calculations) N content per crop and their sources for all crops in M3 and SPAM Maps of N surplus for the SPAM based calculation and the M3 based calculation Supplementary Information

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