Cary, N.C. (October 12, 2016)
With a global population expected to reach 9 billion people by 2050, improved management of key essential nutrients such as phosphorus (P) will be necessary to boost crop yields and stay one step ahead of steeply rising food demand.
Phosphorus is present as phosphate in every cell of our bodies. It is a nutrient required by all living things for basic life-sustaining processes, such as energy storage. Global supplies of phosphate are finite, and most of the largest phosphate reserves are in areas of the world that are prone to political instability, such as Africa and the Middle East.
The phosphorus situation is also challenged by many agricultural soils with insufficient levels of plant-available P, and some soils with a high capacity to fix applied P in slowly available forms due to reactions with calcium, magnesium, aluminum or iron. Crops grown in these soils are not able to obtain sufficient P to meet their needs and cannot reach their full yield potential.
If an applied rate of P is less than optimum for a crop under existing conditions, and a practice such as fertilizer placement is changed that increases nutrient use efficiency, yield will usually increase, at least in the short term. However, in other cases, nutrient use efficiency can increase with no effect on yield if a rate exceeding optimum levels is reduced to optimum.
According to the International Plant Nutrition Institute (IPNI), its soil test summary and evaluation of phosphorus balance – the difference between P application and removal by the crop – does suggest that P is being under-applied in rather significant portions of the U.S. Corn Belt. In such cases where soil fertility levels are less than optimum, an increase in P application rates is called for, even though that rate increase will likely reduce nutrient use efficiency. In other cases, the summary shows P is being over applied and use reductions would be appropriate and would increase nutrient use efficiency without reducing yield.
The lowest soil test P levels in North America are generally found in the Great Plains, but many farmers there are responding to that and slowly building those levels up by increasing P use relative to crop-removal rates.