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CQESTR-Simulated Response of Soil Organic Carbon to Management, Yield, and Climate Change in the Northern Great Plains Region
- Nash, P. R., Sainju, U. M., Gollany, H.T.
- Journal of environmental quality 2017
- Hordeum vulgare, Pisum sativum, arid lands, barley, carbon dioxide, climate change, climatic factors, conventional tillage, cropping sequence, fallow, fertilizer rates, grain yield, greenhouse gas emissions, nitrogen fertilizers, no-tillage, peas, simulation models, soil organic carbon, soil quality, topsoil, Great Plains region, Montana
- Traditional dryland crop management includes fallow and intensive tillage, which have reduced soil organic carbon (SOC) over the past century raising concerns regarding soil health and sustainability. The objectives of this study were to: 1) use CQESTR, a process-based C model, to simulate SOC dynamics from 2006 to 2011, and predict relative SOC trends in cropping sequences that included barley (Hordeum vulgare L.), pea (Pisum sativum L.), and fallow under conventional tillage (CT) or no-till (NT), and N fertilization rates through 2045; and 2) identify best dryland cropping systems to increase SOC and reduce CO2 emissions under projected climate change in eastern Montana. Cropping sequences were conventional till/barley-fallow (CTB-F), no-till/barley-fallow (NTB-F), no-till/continuous barley (NTCB), and no-till/barley-pea (NTB-P), with 0 and 80 kg N ha-1 applied to barley. Under current crop production, climatic conditions, and averaged N rates, SOC at 0 to 10 cm depth was predicted to increase by 1.74, 1.79, 2.96, and 4.57 Mg C ha-1 by 2045 for CTB-F, NTB-F, NTB-P, NTCB, respectively. When projected climate change and the current positive U.S. barley yield trend were accounted for in the simulations, SOC accretion was projected to increase by 0.62 to 0.69 Mg C ha-1 and 0.11 to 0.47 Mg C ha-1, respectively. Based on the model simulations, adoption of NT, elimination of fallow years, and N fertilizer management will likely have the greatest impact on SOC stocks in the top soil as of 2045 in the northern Great Plains.