Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/12/2017
Publication Date: 1/5/2018
Publication URL: http://handle.nal.usda.gov/10113/5935599
Citation: Nash, P.R., Gollany, H.T., Liebig, M.A., Halvorson, J.J., Archer, D.W., Tanaka, D.L. 2018. Simulated soil organic carbon responses to crop rotation, tillage, and climate change in North Dakota. Journal of Environmental Quality. 47:654-662. https://doi.org/10.2134/jeq2017.04.0161.
Interpretive Summary: The use of fallow periods to conserve soil water is a major limiting factor to increasing soil organic carbon (SOC) stocks in dryland crop production systems. Our objectives were to use CQESTR, a carbon model, to simulate soil organic carbon dynamics in the top 12 inches of soil for a 20 years (1993-2012) field study to determine the effects of spring wheat yields and projected climate change for North Dakota on soil organic carbon stocks in relation to management. Also to establish relative soil organic carbon trends due to crop rotation and tillage over the predictive period of 2013-2032, and identify the best dryland cropping systems to increase soil organic carbon stocks under projected climate change in central North Dakota. Intensifying crop rotations was predicted to have a greater impact on soil organic carbon stocks than minimum tillage or no-till over 2013-2032, as soil organic carbon was highly correlated to crop biomass input. Converting from a minimum tillage, spring wheat-fallow rotation to a no-till, continuous spring wheat increased annualized biomass additions by 82% and soil organic carbon by 197 lb/acre/year in the top 12 inches of soil. Climate change is predicted to have a minor impact on soil organic carbon (about 6.5% reduction) relative to crop rotation management, if crop production stays at the 1993-2012 average. The CQESTR model predicted the addition of another spring wheat or rye crop would have a greater effect on soil organic carbon stocks in the top 12 inches than conversion from minimum tillage to a no-till or climate change during 2013-2032 period.
Technical Abstract: 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.