Phosphorus Fertilization

Phosphorus is one of the three major (macro) nutrients required for plant growth. Phosphorus is important in seedling establishment in newly seeded areas. As the turf stand matures phosphorus is a critical component of adenosine triphosphate (ATP) the energy transferring molecule in cells.

In the United States the application of phosphorus to turf is facing increased scrutiny. The greatest concern is in States that border the Great Lakes where phosphorus restriction or bans are being instituted primarily on homelawn turf.

Detrimental effects associated with phosphorus include enhancing algae blooms that can ruin the aesthetics of lakes and streams, and also cause depletion of oxygen impacting the health of fish and other water organisms. Whether the amount of phosphorus from homelawn runoff is of the same magnitude that municipal sewage, detergent, and agriculture fertilizers that caused water pollution in the 1960’s and 70’s is debatable. However, like all nutrient and chemical applications, phosphorus should be applied in an environmentally responsible way. In planning your phosphorus fertilizer program, conduct or check your soil test reports to ascertain the phosphorus levels. This will help you decide whether to increase, decrease, or maintain your phosphorus soil levels.

Given that major nutrient (nitrogen, phosphorus, potassium) concentrations in turfgrass leaf clippings remains rather constant – 4:1:3 (N:P2O5: K2O), the given fertilizer ratio can impact soil phosphorus levels. For example using a fertilizer with a N:P2O5 of 4:1 you will roughly maintain the current soil test levels of phosphorus. If you use a ration less than 4:1 like 2:1 or 3:1 you will contribute to the phosphorus levels in the soil. Conversely, if you use a fertilizer with a ratio greater than 4:1 like 8:1 or 10:1 you will slowly deplete the phosphorus levels in the soil.


Kussow, Wayne. 2004. Phosphorus: Fact or Fiction. Landscape Maintenance.


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