Fate and efficiency of sulfur fertilizer applied to food crops in West Africa

Increased food production in West Africa must be linked to increased fertilizer use. However, the increased use of the high analysis sulfur-free materials currently available in the region will lead to increased incidence of sulfur (S) deficiency. In order to determine the S fertilizer requirements of major cereal crops, and compare the fate and efficiency of alternative S sources, experiments were conducted at six sites in semiarid and subhumid West Africa from 1985–1988. Sulfur fertilizers increased grain yields from 10% to 65% (200 to 2000 kg/ha) in 14 out of 20 site-years (at 5 out of 6 sites). Maximum response was generally obtained with only 5–10 kg S/ha. Both powdered (−60 mesh S⁰) and granular (S⁰-fortified TSP) elemental S sources were usually as effective as sulfate sources (gypsum or SSP). The residual effectiveness of S⁰, however, was superior to that of sulfate at most sites. Sulfur-35 balances demonstrated substantial leaching and low crop recovery (5%–10% of S applied) of fertilizer S. Up to 50% of the applied S was lost from sulfate sources, whereas <20% was lost from S⁰ sources. Although S⁰ sources were at least as effective as sulfate sources, the low S rates required suggest that S deficiencies in the region can be corrected at relatively low cost with sulfate-containing fertilizers, provided they can be supplied at more appropriate nutrient ratios.

Authors and Affiliations

1. Soil Scientist Agro-Economic Division, International Fertilizer Development Center, Muscle Shoals, Ala., USA

   D. K. Friesen

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