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ARS Home » Plains Area » Mandan, North Dakota » Northern Great Plains Research Laboratory » Research » Publications at this Location » Publication #320959
Title: Impacts of crop sequence and tillage management on soil carbon stocks in south-central North Dakota, USA

Author
item Halvorson, Jonathan
item Liebig, Mark
item Archer, David
item West, Mark
item TANAKA, DONALD - Retired ARS Employee

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/28/2016
Publication Date: 4/8/2016
Publication URL: http://handle.nal.usda.gov/10113/6472182
Citation: Halvorson, J.J., Liebig, M.A., Archer, D.W., West, M.S., Tanaka, D.L. 2016. Impacts of crop sequence and tillage management on soil carbon stocks in south-central North Dakota, USA. Soil Science Society of America Journal. 80:1003-1010. doi:10.2136/sssaj2015.09.0331.

Interpretive Summary: Agroecosystems are needed that are robust, highly productive, economically competitive, and environmentally benign. After 18 years of a study to evaluate effects of crop sequence and tillage, we measured soil properties at various depths to 3 feet (91.4 cm) and estimated soil carbon. The experiment, located near Mandan, ND, was designed to evaluate six crop sequences representing a gradient from relatively high to low cropping intensity, managed with either minimum tillage or no-till. We estimated soil carbon using two approaches, by fixed depth and by equivalent soil mass. The equivalent mass method was used to account for differences in soil density expected between tillage practices. Stocks of soil organic carbon calculated by the equivalent mass method (SOCem) were slightly but significantly higher than those calculated by the fixed depth method. Greatest disparities between the two methods, detected near the soil surface, were attributable to the effects of tillage. Stocks of SOCem were not affected by cropping sequence at any partition depth nor by tillage at cumulative depths less than 30.5 cm but significantly more SOCem was observed under no-till than minimum tillage for the 0-61 and the 0-91.4 cm partitions. Organic C in the 0-7.6 cm depth had increased, in 2012, by about 16% since 2001.

Technical Abstract: Increased emphasis has been placed on developing agroecosystems that are robust, highly productive, economically competitive, and environmentally benign. After 18 years of a study to evaluate effects of crop sequence and tillage, we measured soil properties at various depths to 3 feet (91.4 cm) and estimated soil carbon. The experiment, located near Mandan, ND, was designed as a split-plot, with crop sequence as whole plots and tillage (minimum tillage or no-till) as subplots. Crop sequences included continuous spring wheat (Triticum aestivum L.) with crop residue left on the soil surface or with crop residue removed, spring wheat–millet (Setaria italica (L.) Beauv.), spring wheat–safflower (Carthamus tinctorius L.)–fallow, spring wheat–safflower–rye (Secale cereale L.), and spring wheat–fallow. Stocks of soil organic carbon calculated by the equivalent mass method (SOCem) were slightly but significantly higher (P<0.001, paired t-test) than those calculated by the fixed depth method. Greatest disparities between the two methods, detected near the soil surface, were attributable to the effects of tillage. Stocks of SOCem were not affected by cropping sequence at any partition depth nor by tillage at cumulative depths less than 30.5 cm, and averaged about 26, 47, 73, 114 and 156 Mg ha-1 in the 0–7.6, 0–15.2, 0–30.5, 0-61.0, and 0-91.4 cm partitions. However significantly more SOCem was observed under no-till than minimum tillage in both the 0-61 (115.4±2.0 vs 111.8±1.9 Mg ha-1) and the 0-91.4 cm partitions (158.3 ±2.2 vs153.4 ±2.3 Mg ha-1) (P<0.05). Organic C in the 0-7.6 cm depth had increased in 2012 by about 3.2 Mg ha-1 or 16% since 2001.