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Simulated Soil Organic Carbon Responses to Crop Rotation, Tillage, and Climate Change in North Dakota

Nash, P. R., Gollany, H. T., Liebig, M. A., Halvorson, J. J., Archer, D. W., Tanaka, D. L.
Journal of environmental quality 2018 v.47 no.4 pp. 654-662
Secale cereale, Triticum aestivum, arid lands, biomass, climate change, crop production, crop rotation, fallow, minimum tillage, models, no-tillage, rye, soil, soil organic carbon, spring wheat, North Dakota
Understanding how agricultural management and climate change affect soil organic carbon (SOC) stocks is particularly important for dryland agriculture regions that have been losing SOC over time due to fallow and tillage practices, and it can lead to development of agricultural practice(s) that reduce the impact of climate change on crop production. The objectives of this study were: (i) to simulate SOC dynamics in the top 30 cm of soil during a 20-yr (1993–2012) field study using CQESTR, a process-based C model; (ii) to predict the impact of changes in management, crop production, and climate change from 2013 to 2032; and (iii) to identify the best dryland cropping systems to maintain or increase SOC stocks under projected climate change in central North Dakota. Intensifying crop rotations was predicted to have a greater impact on SOC stocks than tillage (minimum tillage [MT], no-till [NT]) during 2013 to 2032, as SOC was highly correlated to biomass input (r = 0.91, P = 0.00053). Converting from a MT spring wheat (SW, Triticum aestivum L.)–fallow rotation to a NT continuous SW rotation increased annualized biomass additions by 2.77 Mg ha⁻¹ (82%) and SOC by 0.22 Mg C ha⁻¹ yr⁻¹. Under the assumption that crop production will stay at the 1993 to 2012 average, climate change is predicted to have a minor impact on SOC (approximately −6.5%) relative to crop rotation management. The CQESTR model predicted that the addition of another SW or rye (Secale cereale L.) crop would have a greater effect on SOC stocks (0- to 30-cm depth) than conversion from MT to NT or climate change from 2013 to 2032.