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.
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).
Incorporating Shrub Residue Increased Soil Organic Matter and Nutrient Availability
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- 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.
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- 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.