Showing papers by "James S. Gerber published in 2021"
University of Maryland Center for Environmental Science1, Technical University of Madrid2, Colorado State University3, Food and Agriculture Organization4, Iowa State University5, University of Minnesota6, Auburn University7, University of Guelph8, University of Hawaii at Manoa9, Washington State University10, National Institute for Environmental Studies11, Potsdam Institute for Climate Impact Research12, Netherlands Environmental Assessment Agency13, Utrecht University14, Ocean University of China15, International Institute for Applied Systems Analysis16, Zhejiang University17, Commonwealth Scientific and Industrial Research Organisation18, Stanford University19, China Agricultural University20
TL;DR: In this article, the authors compare 13 nitrogen budget datasets covering 115 countries and regions over 1961-2015 and find that the most uncertain nitrogen budget terms by country showed ranges as large as their medians, revealing areas for improvement.
Abstract: Input–output estimates of nitrogen on cropland are essential for improving nitrogen management and better understanding the global nitrogen cycle. Here, we compare 13 nitrogen budget datasets covering 115 countries and regions over 1961–2015. Although most datasets showed similar spatiotemporal patterns, some annual estimates varied widely among them, resulting in large ranges and uncertainty. In 2010, global medians (in TgN yr−1) and associated minimum–maximum ranges were 73 (64–84) for global harvested crop nitrogen; 161 (139–192) for total nitrogen inputs; 86 (68–97) for nitrogen surplus; and 46% (40–53%) for nitrogen use efficiency. Some of the most uncertain nitrogen budget terms by country showed ranges as large as their medians, revealing areas for improvement. A benchmark nitrogen budget dataset, derived from central tendencies of the original datasets, can be used in model comparisons and inform sustainable nitrogen management in food systems. Existing datasets of nitrogen (N) balance in agriculture are often discrepant. Comparing 13 of them regarding five metrics (fertilizer application, manure application, biological N fixation, atmospheric deposition, and N harvested as crop products) over 1961–2015 reveals why. Recommendations for improving N quantification and an N budget benchmark dataset are also proposed.
77 citations
Peking University1, Potsdam Institute for Climate Impact Research2, University of Chicago3, Colorado State University4, Icos5, University of Minnesota6, Ludwig Maximilian University of Munich7, China Agricultural University8, Lund University9, University of Maryland, College Park10, University of Natural Resources and Life Sciences, Vienna11, Seoul National University12, Chinese Academy of Sciences13
TL;DR: In this article, a Bayesian framework integrating empirical estimates and gridded global crop models on new maps of the relative difference between attainable rainfed and irrigated yield (ΔY) was developed for wheat and maize at global scale, with large spatial differences driven more by patterns of precipitation than that of evaporative demand.
Abstract: Irrigation is the largest sector of human water use and an important option for increasing crop production and reducing drought impacts. However, the potential for irrigation to contribute to global crop yields remains uncertain. Here, we quantify this contribution for wheat and maize at global scale by developing a Bayesian framework integrating empirical estimates and gridded global crop models on new maps of the relative difference between attainable rainfed and irrigated yield (ΔY). At global scale, ΔY is 34 ± 9% for wheat and 22 ± 13% for maize, with large spatial differences driven more by patterns of precipitation than that of evaporative demand. Comparing irrigation demands with renewable water supply, we find 30-47% of contemporary rainfed agriculture of wheat and maize cannot achieve yield gap closure utilizing current river discharge, unless more water diversion projects are set in place, putting into question the potential of irrigation to mitigate climate change impacts.
41 citations
29 Jun 2021
21 citations