World Sulfur Use Efficiency for Cereal Crops

Sulfur (S) is an essential plant nutrient needed for higher crop yields and improved nutritional value. In recent decades, the occurrence of S deficiency has increased and fertilizer S use may steadily increase. This may lead to inefficient crop utilization of S and result into negative footprints on the environment. The objective of this work was to estimate world fertilizer sulfur use efficiency (SUE) for major cereal crops grown around the world. A 10-yr data set (2005-2014) was obtained from the Food and Agriculture Organization, the US Geological Survey, and an array of other published research articles. Statistical analysis was performed using MS Excel to obtain total area for world and cereal crops, grain yield, and fertilizer S applied. The difference method [(Total grain S - grain S derived from the soil)/S applied] was used to compute world SUE. Cereal crops included in this study were barley (Hordeum vulgare L.), maize (Zea mays L.), rice (Oryza sativa L.), millet (Pennisetum glaucum L.), wheat (Triticum aestivum L.), sorghum (Sorghum bicolor L.), rye (Secale cereale L.), and oat (Avena sativa L.). Cereal production increased from 2669 M Mg in 2005 to 3346 M Mg in 2014. Sulfur use efficiency for cereal crops was estimated to be 18%. This low SUE may be attributable to S leaching from the soil profile, immobilization, retention in residues, and adsorption. As increased quantities of fertilizer S are likely to be applied in future to meet the ever-growing demand for food, SUE could decline below 18%.