Nitrogen budget data

Input-output estimates of nitrogen (N) on cropland are essential for
improving N management and better understanding the global N cycle. Here,
we compare 13 N budget datasets covering 115 countries and regions over
1961-2015. Though most datasets showed similar spatiotemporal patterns,
some annual estimates varied widely among them, resulting in large ranges
and uncertainty. In 2010, global medians (in Tg N yr-1) and associated
min-max ranges were 73 (64-84) for global harvested crop N; 161 (139-192)
for total N inputs; 86 (68-97) for N surplus; and 46% (40%-53%) for
nitrogen use efficiency. Some of the most uncertain N budget terms by
country showed ranges as large as their medians, revealing areas for
improvement. A benchmark N budget dataset, derived from central tendencies
of the original datasets, can be used in model comparisons and inform
sustainable N management in food systems.