Modeling symbiotic biological nitrogen fixation in grain legumes globally with LPJ-GUESS (v4.0, r10285)

• Published in: Geoscientific Model Development 2022-01, Vol.15 (2), p.815-839
• Main Authors: Ma, Jianyong, Olin, Stefan, Anthoni, Peter, Rabin, Sam S, Bayer, Anita D, Nyawira, Sylvia S, Arneth, Almut
• Format: Article
• Language: English
• Subjects: Agricultural ecology; Agricultural ecosystems; Agricultural production; Agricultural Science; Agricultural Science, Forestry and Fisheries; Agricultural Sciences; Agriculture; Analysis; Biomass; Broad beans; Carbon; Climate and land use; Climate change; Climate effects; Crop yield; Crops; Earth and Related Environmental Sciences; Ecosystems; Environment models; Environmental impact; Estimates; Fertilizers; Fixation; Food; Food production; Geovetenskap och miljövetenskap; Grain; Jordbruksvetenskap; Land use; Lantbruksvetenskap och veterinärmedicin; Lantbruksvetenskap, skogsbruk och fiske; Legumes; Manures; Modelling; Natural Sciences; Naturgeografi; Naturvetenskap; Nitrogen; Nitrogen fixation; Nitrogenation; Physical Geography; Simulators; Soil; Soil fertility; Soil moisture; Soil temperature; Soybean; Soybeans; Sustainability; Sustainable agriculture; Symbionts; Terrestrial environments; Uptake; Vegetation
• ISSN: 1991-9603; 1991-959X; 1991-962X; 1991-9603; 1991-962X
• DOI: 10.5194/gmd-15-815-2022

Biological nitrogen fixation (BNF) from grain legumes is of significant importance in global agricultural ecosystems. Crops with BNF capability are expected to support the need to increase food production while reducing nitrogen (N) fertilizer input for agricultural sustainability, but quantification of N fixing rates and BNF crop yields remains inadequate on a global scale. Here we incorporate two legume crops (soybean and faba bean) with BNF into a dynamic vegetation model LPJ-GUESS (Lund–Potsdam–Jena General Ecosystem Simulator). The performance of this new implementation is evaluated against observations from a range of water and N management trials. LPJ-GUESS generally captures the observed response to these management practices for legume biomass production, soil N uptake, and N fixation, despite some deviations from observations in some cases. Globally, simulated BNF is dominated by soil moisture and temperature, as well as N fertilizer addition. Annual inputs through BNF are modeled to be 11.6±2.2 Tg N for soybean and 5.6±1.0 Tg N for all pulses, with a total fixation of 17.2±2.9 Tg N yr−1 for all grain legumes during the period 1981–2016 on a global scale. Our estimates show good agreement with some previous statistical estimates but are relatively high compared to some estimates for pulses. This study highlights the importance of accounting for legume N fixation process when modeling C–N interactions in agricultural ecosystems, particularly when it comes to accounting for the combined effects of climate and land-use change on the global terrestrial N cycle.