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Review article2022Peer reviewed

Quantifying country-to-global scale nitrogen fixation for grain legumes II. Coefficients, templates and estimates for soybean, groundnut and pulses

Herridge, David F.; Giller, Ken E.; Jensen, Erik S.; Peoples, Mark B.


Background The demand for estimates of biological nitrogen (N) fixation inputs in agricultural systems is driven by the need to effectively manage the global N cycle.Scope We present a methodology for quantifying N-2 fixation by the grain legume-rhizobia symbioses that can be used for any year or sequence of years for which area and production statistics for legume oil-seed and pulse crops were available and at country-to-global scales. The coefficients used in the templates - harvest index, N harvest index, %N shoots, %N grain and a factor to account for below-ground N - were aggregated from 224 reports containing > 4,000 observations. Values for the % total crop N derived from atmospheric N-2 (%Ndfa) for specific grain legumes and regions were determined in a companion paper. The grain legumes were estimated to fix a global total of 35.5 Tg N in the year 2018 - 25.0 Tg for soybean (Glycine max), 7.2 Tg for the pulses and 3.3 Tg for groundnut (Arachis hypogaea). Soybean dominated global grain legume N-2 fixation, with 38 % of total N fixed associated with soybean in South and Central America and a further 22 % by soybean in North America.Conclusions The updated estimates of N-2 fixation by the grain legumes inform us of a substantial and increasing role that biological N-2 fixation plays in global agricultural systems. The challenge remains to reliably estimate N inputs from other N-2-fixing organisms that are active in these systems.


Nitrogen fixation; regional; global estimates; templates; legumes; pulses; oilseed legumes; rhizobia; soybean

Published in

Plant and Soil
2022, Volume: 474, number: 1-2, pages: 1-15
Publisher: SPRINGER

    UKÄ Subject classification

    Agricultural Science

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