Phosphorus is very important to stimulate early growth, help with tillering, and improve winter survival. The amount of phosphorus to be applied depends on the soil test levels as well as the phosphorus-supplying power of the soil. It is recommended that the soil test level be at 40, 45, and 50 pounds per acre for the high-, medium-, and low-phosphorus-supplying power soils, respectively.

If the soil test is below the desired level, it is recommended to apply sufficient phosphorus to build up the soil as well as supplying what the crop will remove. If test levels are adequate, it is recommended that sufficient phosphorus be applied at planting time to replace 1.5 times the amount to be removed by the crop. This large amount is needed to meet the high phosphorus requirements of wheat.

“In many fields, a typical rate of 150 pounds of DAP (18-46-0) per acre supplies not only phosphorus, but also sufficient nitrogen for the establishment of the crop,” Fernandez said. “Sometimes it might be tempting to reduce or eliminate phosphorus application in soils testing at or just above the critical level. If your finances do not allow for a full application, it is strongly suggested that 80 to 100 pounds of DAP per acre be applied to ensure a good supply of readily available phosphorus to help adequate establishment of the crop.”

Potassium is also an important nutrient, but wheat normally does not respond to applications of this nutrient unless soil test levels are extremely low (less than 100 pounds per acre). Since soybean and corn are grown in the rotation with wheat, and are more responsive to potassium than wheat, it is recommended to manage this nutrient to maximize yield of corn and soybean, he said. This will automatically take care of the potassium needs of wheat.  

For more information, read The Bulletin online.