Carbon Sequestration and Nutrient Availability

Two 11 yr field studies  (initiated in 2004) at elevated densities (Piliostigma reticulatum (PS) at 1000 and Guiera Senegalensis (GS) at 1500 ha-1) and annual coppiced residue soil amendments (with 0 to 1.5X recommended N-P-K rates) showed that shrubs:

  • increased total soil C by >11% (PR) to 127 % (GS)  from 2012 to 2015. Notably, total C decreased (23 - 39%) in the minus shrub plots.

  • The most dramatic effects on soil C was with GS on the sandy soil of northern Senegal. Here POM-C, the easily mineralized C, rose by 39% in plus shrub plots but decreased by 36%  in minus shrub plots from 2007 to 2015.

  • Four of the six macronutrients (N, K, Ca, Mg) and 1 of 4 analyzed micronutrients (Mn) were significantly greater during at least 2 of the sampling periods (planting, midseason or harvest) in both 2014 and 2015 for both shrub species.

  • Soil inorganic N and plant available PO4 were consistently greater in the presence of both shrub species during the growing season.

Improved Soils

Fig. 1. Effect of G. senegalensis on total C and distribution of the POM-C, and C <53 µm fractions over 4 fertilizer rates at harvest in 2012, 2013, and 2015 (Pairs of +shrub and –shrub total C values within a fertilizer rate followed by the same letter are not statistically different at <P 0.05).

Total Carbon over four fertilizer rates at harvest.

 

Incorporating Shrub Residue Increased Soil Organic Matter and Nutrient Availability

Root Turnover

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  2. Dossa, E.L., S. Diedhiou, J. E. Compton, K. B. Assigbetse and R. P. Dick. 2010. Spatial patterns of P fractions and chemical properties in soils of two native shrub communities in Senegal. Plant Soil. 327:185-198.
  3. Dossa, E.L., I. Diedhiou, M. Khouma, M. Sene, A. Lufafa, F. Kizito, S. A. N. Samba, A. N. Badiane, S. Diedhiou, and R. P. Dick. 2012. Crop Productivity and Nutrient Dynamics in a Shrub (Guiera senegalensis)–Based Farming System of the Sahel. Agron. J 104:1255–1264.
  4. Dossa Ekwe L., I. Diedhiou, M. Khouma, M. Sene, A. N. Badiane, N.A.S. Ndiaye, K. B. Assigbetse, S. Sall, A. Lufafa, F. Kizito, R.P. Dick, and J. Saxena. 2013. Crop Productivity and Nutrient Dynamics in a Shrub (Piliostigma reticulatum)-Based Farming System of the Sahel.  J. Agron. 105:1237-1246.
  5. Lufafa, A., I. Diédhiou, S. Ndiaye, M. Séné, M. Khouma, F. Kizito, R.P. Dick, and J.S. Noller. 2008. Carbon stocks andpatterns in native shrub communities of Sénégal’s Peanut Basin. Geoderma 146: 75-82.
  6. Lufafa, A., Wright, D., Bolte, J., Diédhiou, I., Khouma, M., Kizito, F., Dick, R.P., Noller, J.S., 2008. Regional carbon stocks and dynamics in native woody shrub communities of Senegal’s Peanut Basin. Agriculture, Ecosystems and Environment 128:1–11.
  7. Lufafa, A.; Diedhiou, I.; Ndiaye, N.A.S.; Sene, M.; Kizito, F.; Dick, R.P.; Noller, J. 2009. Allometric relationships and peak-season community biomass stocks of native shrubs in Senegal's Peanut Basin. Journal of Arid Environments. 73:260-266
  8. Iyamuremye, F., V. Gewin, R.P. Dick, M.Diack, M.Sene, A.N. Badiane, and M. Diatta. 2012. Carbon, nitrogen, and phosphorus mineralization of agroforestry plant residues in soils of Senegal. J. of Arid Soil Research and Rehabilitation 14:359-371.