Quantifying Soil Carbon Sequestration: Textural Effects

The role of carbon dioxide (CO₂) as one of the greenhouse gases contributing to global warming is the focus of considerable research in agriculture. Soils have the potential to store atmospheric carbon (C) as soil organic matter or soil organic C (SOC). Developing an understanding of those factors which influence the capacity of a soil to store C, reducing atmospheric levels and improving soil quality, is the focus of this research. An established long-term rotation study at Swift Current was used to evaluate the impact of fertilizer management and crop rotation on SOC levels.

The evaluation of soils from this long-term experiment found that those receiving supplemental nitrogen (N) and phosphorus (P) fertilizer, based on soil test recommendations, significantly increased SOC in the surface 3 in. over application of P alone. Soil texture is known to influence the stability of SOC. In this study clay content was relatively uniform. Hence it did not influence SOC. The amount of sand or silt accounted for 36 percent of the variability measured in organic C. However, this influence was restricted to a few small areas where the sand or silt content of the soil reached extremely high or low values. For the majority of the trial area, it was the combination of rotation and balanced fertilization that had the greatest influence on measured SOC. SK-30F