Sulphur Contents in Arable Soils from Four Agro-Ecological Zones of Ghana

Abstract

There is limited data on Sulphur (S) contents in arable soils for appropriate fertilizer recommendations in Ghana. Five study areas in a reconnaissance survey (RS), followed by an in-depth study of two areas comprising farms of different durations of cultivation, were investigated for the current total S and sulphate contents. Basic soil properties were measured using standard laboratory procedures. Total S and sulphate contents were determined using LECO instrument dry combustion and HPLC, respectively. The results showed wide variations in total S contents from 31 to 603 mg kg−1 in the Guinea Savannah (GS) zone. The mean trend was Forest > Forest-Transition (F-S) > north Guinea Savannah (nGS) > Deciduous Forest (DF) > south Guinea Savannah (sGS) in the RS sites, with a similar trend in the main study sites. Sulphate contents ranged from 5 to 25 mg kg−1, constituting 0.8 to 37% of the total S. The mean percent trend was sGS = DF > Forest > nGS > F-S. Soil organic carbon (SOC) was the major predictor of total S along with pedogenic minerals. Total S and crystalline pedogenic minerals predicted the sulphate contents. The results highlight the need for ecologically-based S fertilizer programmes to boost crop yields.