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

Authors: BOUBAKRY, C - International Crops Research Institute For The Semi-Arid Tropics (ICRISAT); Agyin-Birikorang, Sampson; ADU-GYAMFI, RAPHAEL - University Of Environment And Sustainable Development; Chambers, Rachel; TINDJINA, IGNATIUS - International Fertilizer Development Center (IFDC); ANGZENAA, ALBERT - International Fertilizer Development Center (IFDC)

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/25/2023
Publication Date: 9/21/2023
Citation: Boubakry, C., Agyin-Birikorang, S., Adu-Gyamfi, R., Chambers, R.A., Tindjina, I., Angzenaa, A. 2023. Improving agronomic effectiveness of elemental sulfur to increase productivity in sulfur-deficient soils. Agronomy Journal. 115(6):3131-3143. https://doi.org/10.1002/agj2.21458.
DOI: https://doi.org/10.1002/agj2.21458

Interpretive Summary: Elemental sulfur (ES), a byproduct of oil and gas processing, could be a cheaper alternative S fertilizer source if its bioavailability can be improved. One way to achieve this is to increase the specific surface of ES by reducing its particle size. We conducted field trials at six locations across three countries: two each in USA, Ghana, and Mali, to determine the agronomic effectiveness of micronized ES (MES). Specific objectives were to quantify (i) corn productivity, (ii) sulfur recovery, and (iii) residual soil S concentration; as influenced by MES fertilizer application. We compared agronomic effectiveness of MES to ammonium sulfate (AS), a commercially available sulfate fertilizer, at four application rates [(i) locally recommended S application rate (SR), (ii) 50%¬¬_SR, (iii) 75%_SR, and (iv) 125%_SR)] and a control where no S was applied. Averaged across all locations in the three growing seasons, applying AS at 50%_SR increased corn yield by =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 =6% and at 75%_SR, yield increased by =26%. Increasing 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 potential profitability of using MES fertilizer product for crop production.

Technical Abstract: Sulfate-containing fertilizers are the most commonly used sulfur (S) sources for crop production globally. However, elemental sulfur (ES), a byproduct of oil and gas processing, could be a cheaper alternative S fertilizer source if its bioavailability in soils can be improved since pure ES tends to be inert, hydrophobic, and requires oxidation to sulfate before plants can utilize the containing S. One easy way of achieving this is to increase the specific surface of ES by reducing the particle size. We conducted field trials at six locations across three countries: two each in USA, Ghana, and Mali, to determine the agronomic effectiveness of micronized ES (MES). Specific objectives were to quantify (i) corn productivity, (ii) sulfur recovery, and (iii) residual soil S concentration; as influenced by the MES fertilizer application. We compared the agronomic effectiveness of MES to a commercially available sulfate fertilizer product, ammonium sulfate (AS), at four application rates [(i) locally recommended S application rate (SR), (ii) 50%_SR, (iii) 75%_SR, and (iv) 125%_SR)] and a control where no S was applied. Averaged across all locations in the three growing seasons, for the AS fertilizer source, applying the limiting essential nutrients with a modest rate of 50%_SR increased corn yield by 8%, relative to the control. Further increases to 75%_SR, SR, and 125%_SR resulted in yield increases of 12%, 26% and 28%, respectively, compared to the control. With MES, at 50% SR, yield increased by =6% and at 75% SR, yield increase of =26% was observed. Further increases in S application rate to SR and 125%_SR resulted in marginal yield increases =28 %, compared to the control. For the untreated ES, marginal yield increases of =10% was observed only when the product was applied at 125%_SR. Application of the MES-fertilizer product resulted in the greatest apparent S use efficiency by improving S recovery efficiency and a consequent reduction of S losses, compared to AS and ES. The combined data suggest that MES could be an alternative S source for crop production. Therefore, with the additional environment benefits of minimizing S losses from the applies fertilizer, we conclude that MES could be an efficient S fertilizer source. However, economic analysis is needed to determine potential profitability of utilizing MES-fertilizer products as alternative S sources for crop production. In situations where the only S source is untreated ES, a relative high application rates of at least 125%_SR should be used.