Improving agronomic effectiveness of elemental sulfur to increase productivity in sulfur-deficient soils

Elemental sulfur (ES), a byproduct of oil and gas processing, could be an alternate sulfur (S) fertilizer source for crop production if its bioavailability is improved. Increasing the specific surface of ES by reducing its particle size can accelerate ES oxidation to enhance its bioavailability. In field trials at six locations across three countries: two each in the United States, Ghana, and Mali, we determined the agronomic effectiveness of micronized ES (MES). Specific objectives were to quantify (i) corn (Zea mays L.) productivity, (ii) S recovery, and (iii) residual soil S concentration; following MES application, compared to ammonium sulfate (AS), a commercially available sulfate fertilizer, at four application rates-(i) locally recommended sulfur application rate (SR), (ii) 50%_SR, (iii) 75%_SR, and (iv) 125%_SR-and a control where no S was applied. Averaged across all sites and in the three growing seasons, AS at 50%_SR increased corn yield by & LE;8% relative to control. Increasing to 75%_SR, SR, and 125%_SR resulted in 12%, 26%, and 28% yield increases, respectively. Applying MES at 50%_SR increased yield by & LE;6%, and at 75%_SR, yield increased by & LE;26%. Increasing the S application rate to SR and 125%_SR resulted in marginal yield increases. The combined data suggest that MES can be applied at a reduced rate of 75_SR to achieve similar yields as AS applied at SR. We conclude that MES could be an efficient S fertilizer alternative. However, economic analysis is needed to determine the potential profitability of using MES fertilizer products for crop production. Particle size reduction can improve the bioavailability of elemental sulfur (ES), making it an effective sulfur (S) fertilizer.At the recommended S rate, micronized elemental sulfur (MES) was as effective as ammonium sulfate (AS) as an S fertilizer source.MES was more effective than AS at a reduced (75%) sulfur application rate.MES had additional environmental benefits of reducing S losses as those associated with AS.MES could be an efficient S source for sustainable and profitable crop production in S-deficient soils.