Six Years of Tillage Influenced Soil Carbon Fractions within Corn-Sugarbeet-Soybean Rotation In Silty Clay Soil of North Dakota.

Conservation tillage plays a critical role in maintaining the soil health. Different physical, chemical, and biological fractions of soil organic carbon (SOC) pools, such as  microbial biomass carbon (MBC), coarse particulate organic matter C (CPOM-C), and potassium permanganate oxidizable C (KMnO₄-C), respond to the changes in management practices and thus provide early and sensitive indications of changes in the soil carbon dynamics. A long-term field experiment with three tillage treatments, no-till (NT), strip till (ST), and conventional till (CT), within a corn-sugarbeet-soybean was conducted on high clay soils at the NDSU campus experimental farms in Fargo, North Dakota since 2005. In the fall of 2011, bulk soils were collected from the 0-15 cm depth to determine the effect of three tillage treatments on soil organic C, MBC, CPOM-C, and KMnO₄-C, and the relationships among these C fractions. The NT and ST treatments had significantly higher average CPOM-C compared to CT in both sugarbeet and soybean (p<0.05). Similarly, the average KMnO₄-C was significantly higher under NT and ST than CT in sugarbeet (p<0.05). The outcomes from this experiment show that soil organic carbon and its fractions can be increased with a reduction in tillage on high clay soil.