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A current estimate of global phosphorus use effi ciency (PUE) for cereal production is not available. Th e objectives of this paper were to estimate PUE for cereal crops grown in the world and to review methods for improvement. Phosphorus use effi ciency was determined using world cereal harvested area, total grain production, and P fertilizer consumption from 1961 to 2013, in addition to assumptions established from previous literature. World PUE of cereal crops was calculated using both balance and diff erence methods. Using the balance method, cereal grain P uptake is divided by the P fertilizer applied. Alternatively, the diff erence method accounts for P coming from the soil and that is subtracted from applied P. Utilized in this analysis is the estimate that cereal production accounts for 61% of the total harvested cropland. Cereal grain yields increased from 1.35 to 3.90 Mg h -1 between 1961 and 2013. In 1961, the world's fertilizer P consumption was 4,770,182 Mg and increased to 16,662,470 Mg of P fertilizer by 2013. Th is represents a 3.5× increase in P fertilizer consumption over 53 yr. Phosphorus use effi ciency estimated using the balance method was 77%. Using the diff erence method, PUE for cereal production in the world was estimated to be 16%.

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Core Ideas Potassium use efficiency in cereals is unknown. World demand for potassium in agriculture is increasing. Potassium is a non‐renewable resource. Worldwide potassium (K) fertilizer use has grown, while the expected fertilizer use efficiency has decreased. The objective of this paper was to estimate potassium use efficiency (KUE) for cereal crops and report on methods that will most likely lead to improved KUE. World KUE was calculated using the total area under cereal production, total cereal grain production, percent K content in cereal grains and K fertilizer consumed from 1961 to 2015. All data was obtained from FAOSTAT except percent K grain content, which was acquired from the USDA. The reported KUE estimate included assumptions established in prior literature. The percent K coming from the soil was estimated at 71%, while previous year K fertilizer‐residual‐effects were offset by knowing that similar amounts of fertilizer K will be applied in following years. At current consumption rates, existing K reserves as K20 are estimated to last 100 yr meaning that mining operations will need to expand to meet expected market demands. Results showed that cereal production increased by a factor of 3.2 from 1961 to 2015 and that was accompanied by a threefold increase in fertilizer K consumed. Estimated KUE from 1961 to 2015 for world cereal crops using the difference method was 19%. Combined with findings from this paper, estimates of N, P, and K use efficiency for cereal production in the world stand at 33, 16, and 19%, respectively.

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%. Core Ideas World sulfur use efficiency for cereal crops is unknown. World sulfur use efficiency for cereal crops was estimated to be 18%. More precision agriculture research is necessary to improve sulfur use efficiency for cereal crops. Reasons for low sulfur use efficiency include sulfur; leaching, adsorption, retention in residues, and immobilization as well as failure to adhere to sound agronomic practices and 4R concepts.