SULFUR STATUS AND FORMS IN SOME SURFACE SOILS OF GHANA1

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Abstract
We analyzed surface samples of 48 important soil series developed over the major parent materials in the different ecological zones of Ghana for total S, inorganic sulfate-S, HI-reducible S, carbon-bonded S, organic C, total N, and total and organic P. Total S ranged from 44–281 ppm (average, 129 ppm), organic S ranged from 37–268 ppm (average, 121 ppm; 94% of total S) and sulfate-S content ranged from 3–22 ppm (average, 7.8 ppm; 6% of total S). Ester sulfate, calculated from HI-reducible S, ranged from 5–123 ppm (average, 63.7 ppm), and carbon-bonded S ranged from 1–57 ppm (average, 16.9 ppm). Total S was significantly correlated with organic C (r = 0.85***), with total N (r = 0.75***), and with organic P (r = 0.66***). The soils had average C:N, N:S, N:P, P:S, C:S, and C:N:P:S ratios of 10.7:1, 6.8:1, 11.4:1, 0.7:1, 65.7:1, and 102:10:1.0:1.5 respectively. Assessment of the data indicated that parent material, organic matter content, vegetative cover, and, to a lesser extent, pH had influenced the S status of the soils. Soils formed over Birrimian rocks and phyllite and basic rocks had higher S status than soils formed over acidic rocks, alluvium, and shales or sandstones and Tertiary sands. Forest soils had higher S status than savanna soils on account of their higher organic matter content. Incubation studies showed that, of the 48 soils, 18 resulted in net immobilization, and the rest yielded only small amounts of mineralized S (average, 2.2 ppm). Net mineralized S was weakly corrected with sulfate-S (r = 0.39**) and pH (r = −0.35*), but not with total S, organic C, total N, or arylsulfatase activity. Generally, the soils showed relative low sulfate adsorption capacity (range 6–46; average, 20 ppm). © Williams & Wilkins 1987. All Rights Reserved.