Soil carbon dynamics and crop residue yields of cropping systems in the Northern Guinea Savanna of Burkina Faso uri icon

abstract

  • Concerns about effects of increasing atmospheric concentration of carbon dioxide (CO,) on climate has given rise to the possibility of emission credits for soil organic carbon (SOC) sequestration. The goal of this study was to analyze SOC sequestration options in cropping systems of the Northern Guinea Savanna of West Africa. An 11-year experiment from the region, which consisted of 56 cropping system treatments that combined various crop rotation sequences with various input levels and an additional treatment of native grass fallow, was analyzed. Rotations included one or more of: sorghum (Sorghum bicolor (L.) Moench), cotton (Gossypium hirsutum L.), groundnut (Arachis hypogaea L.), maize (Zea mays L.) and native grass fallow. Inputs were defined by whether or not the plots were plowed and the addition of soil amendments (N, nitrogen; P, phosphorous; K, potassium; D, dolomite; CR, crop residues; CP, compost and ME, manure). Plots were moldboard plowed before seeding, except fallows, which were not plowed. Soil organic carbon in select treatments and residue yields from all cropped treatments were analyzed. The slope parameters from the regression analysis of SOC in the continuous fallow treatment were not significantly different from zero (P > 0.05), suggesting SOC (0.53% after I I years) was at steady state in this treatment. Rotation and input significantly affected SOC (P < 0.05), but interaction effects were not significant. After I I years, the cropped rotation with the greatest SOC was sorghum-fallow (0.46%), which was significantly greater (P < 0.05) than SOC in other the rotations measured: continuous cotton (0.36%), continuous sorghum (0.35%), and cotton-maize-sorghum (0.33%). For the input levels, addition of P, K, and ME gave the greatest SOC (0.44%) after I I years of cropping, which was significantly greater (P < 0.05) than SOC from the N, P, K and D (0.37%), no input (0.32%) and N, P and K (0.34%) treatments. In addition, SOC with inputs of N, P, K and D (0.37%) was significantly greater than SOC with no input (0.32%). Three management practices, which had significantly greater SOC than others and were among the best for yields, were identified as sequestering management options for the region. These were rotating sorghum and fallow, and amending the soil with mineral P, K, and ME or N, P, K and D. However, potential drawbacks, such as a risk of reduced production with increased fallows, must be identified and addressed if the options are to be adopted. (c) 2006 Elsevier B.V. All rights reserved.

publication date

  • 2007
  • 2007
  • 2007