Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 7/28/2015
Publication Date: 11/16/2015
Citation: Halvorson, J.J., Liebig, M.A., Archer, D.W., Tanaka, D.L. 2015. Impacts of crop sequence and minimum and no-till cropping systems on soil carbon stocks in south-central North Dakota, USA. ASA-CSSA-SSSA Annual Meeting Abstracts. [abstract].
Technical Abstract: Increased emphasis has been placed on developing agroecosystems that are inherently resistant and resilient to external stressors, yet are highly productive, economically competitive, and environmentally benign. As part of a long-term study to evaluate effects of crop sequence and tillage on crop yield, precipitation use, and soil properties, we measured soil carbon at various depths to 3 feet (91.4 cm) and estimated stocks of soil carbon on both a volumetric and equivalent soil mass basis. The study location, approximately 6 km south of Mandan, ND (46°46'12'' N, 100°54'57''W), was characterized by gently rolling uplands (0–3% slope) with a predominant soil of Temvik–Wilton silt loam (fine-silty, mixed, superactive, frigid Typic and Pachic Haplustolls). The experimental design was a split-plot, with crop sequences 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, continuous spring wheat 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) and highly correlated (Pearson’s r =0.93-0.99) with those calculated by the simpler volumetric approach (SOCv) with greatest disparities detected for estimates of stocks in thin layers near the soil surface. Stocks of SOCem were unaffected by either crop sequence or tillage to a cumulative depth of 61 cm, averaging about 26, 47, 73, 114 and 156 Mg ha-1 in the 0–7.6, 0–15.2, 0–30.5, 0-61.0,cm partitions. Average SOCem was greater (p<0.05) under no-till management (158.3±2.2 Mg ha-1) than minimum tillage (153.4±2.3 Mg ha-1) for the 0-91.4 cm partition. Contrary to expectations, increased crop diversity and cropping intensity, and retention of crop residues had no discernible effect on stocks of SOC. However, it is important to consider the effects these crop sequences may have on crop productivity, input use, and other soil ecosystem services.