Soil carbon stock and nutrient characteristics of Senna siamea grove in the semi-deciduous forest zone of Ghana

We report soil carbon stock (SCS) and nutrient characteristics of a pure stand of Senna siamea grove in comparison with adjacent cropland using t-test. This study was conducted in 2018 at the Kwame Nkrumah University of Science and Technology, Kumasi. Soil sampling up to 50 cm depth was carried out from five subplots in each ecosystem. The SCS of the grove at 0-15 cm depth was over 100% greater (30.78 Mg/ha) than that of the cropland (15.16 Mg/ha). Soil pH and total N content of the grove were 5.75 +/- 1.22 and 0.10 +/- 0.03% in the topsoil (0-15 cm) and 5.52 +/- 0.80, 0.06 +/- 0.01% and 5.03 +/- 1.22, 0.04 +/- 0.01% in the 15-30 and 30-50 cm depths, respectively. Although these values were greater in the grove than the cropland, the available phosphorus content was 3-4 fold greater in the latter soil. The two ecosystems affected soil organic carbon and total nitrogen contents significantly (p < 0.05) only in the topsoil, but had a significant influence on soil available phosphorus in both the topsoil and the subsoil. Sand content of the grove seemed to explain greater variability in its SCS (R-2 = 0.81) than clay content. The greater SCS of the Senna grove demonstrates its role in soil carbon storage in tropical climate in the era of climate change.