Small plants need more phosphorus than most other nutrients, making it important to have this phosphorus available for growth early in the growing season. Previous research conducted on soils testing less than 30 pounds of phosphorus has shown both an early season growth response and a yield response to banded phosphorus. However, more recent research on soils testing higher in phosphorus has not shown the yield response from banded phosphorus even though there may be an early season improvement in plant growth. There is little chance that banded phosphorus will increase crop yields of most field crops when grown on mineral soils testing above 60 pounds per acre. More than half of the soils in Michigan used for field crop production test very high in available phosphorus.
Research shows that some reduction in soil test levels can occur without reducing crop yields.
Research shows that drawdown of soil test P is similar to buildup, taking 5 to 18 pounds of P2O5 removal to decrease the soil test 1 pound. Reducing the amount of phosphate fertilizer applied does not cause a sudden reduction in the soil test value of high testing soils. When phosphorus is recommended for crops grown on organic soils, banding 25-40 pounds of phosphate per acre is suggested, particularly for early planted crops. However, when soil test levels are high, banded phosphorus is not suggested. In newly developed fibrous peats, banded phosphorus applications are more effective because phosphorus remains fairly mobile.