Healthy lawns depend on a well-balanced fertilizer program that provides the essential elements it needs like: Nitrogen (N), Phosphorus (P) and Potassium (K). A healthy lawn is necessary to successfully ward off weeds, insects and disease. Although most fertilizers contain a variety of elements, in this article we are going to focus on just phosphorus (P)! Phosphorus is a macronutrient (just like nitrogen and potassium), and when needed, is required in larger quantities because it is normally bio-unavailable in the soil. Phosphorus, which is found in every living plant cell is vital in seed germination, establishing root growth and plant development. Without phosphorus, grass would appear stunted, especially in early stages of growth. Discover why phosphorus’ role in turf and soil is important to the overall health of a lawn:

Phosphorus or “P” is a primary plant nutrient that is involved in the metabolic processes responsible for transferring energy throughout the plant. It is crucial to introduce phosphorus when first establishing turf grass and remains important as the grass continues to grow. The presences of phosphorus in soil helps turf grow lush and thick because it promotes strong root growth. An abundance of phosphorus allows plants to grow more efficiently.

Phosphorus deficiencies can be difficult to identify because they often mimic other nutrient deficiencies or pest invasions. It’s advised to do a soil test to determine deficiencies prior to applying phosphorus. For example, low “P” in soil can take on the signs of nitrogen deficiency in new growth, appearing yellow and weak. An inadequate amounts of phosphorus in the soil can also represent itself as reduced leaf expansion and surface area, in addition to limited numbers of blades. Both shoot and root growth could also look stunted, leading to less root mass to uptake nutrients and water. Phosphorus deficiencies can result as a buildup of carbohydrates through photosynthesis, resulting in foliar deficiency (this can be seen as an abnormal dark green leaf color). Sugars can accumulate as well, causing anthocyanin pigments (a reddish–purple color) to appear.

NOTE: Carbohydrate buildup and anthocyanin pigments will usually occur at extremely low phosphorus levels in soil. Be careful to check for insect damage as well; pest invasion damage can resemble the look of anthocyanin pigments.

Phosphorus is tightly regulated because this nutrient has been known to cause the degradation of surface water quality. Fortunately, most soil already contains enough phosphorus to sustain root development and growth of established turf. Regulations have been established to allow lawns to have the nutrients they need, when needed (example: early turf development), while keeping the waterways clean. Each state has different phosphorus regulations, so fertilizers should be selected carefully based on turf’s needs and state regulations. Talk with your country extension office for more information about phosphorus regulations in your state. Also, conduct a soil test to determine if phosphorus is lacking within you soil and at what rates it should be applied. If you’re starting a new lawn, plants will benefit from a starter fertilizer that contains phosphorus to help develop healthy root systems, stimulate growth, and assist with energy reactions throughout the plant.

• PROtip: Overall, the best method to make phosphorus in soil available for plant uptake is by adopting a regular lawn care routine. This includes proper fertilization, proper soil amendments management, proper mowing and watering, as well as proper aeration and thatch management.

Phosphorus is associated with healthy root development and growth, but plants use it for many other processes. Phosphorus is vital, especially when starting a new lawn, repairing a lawn or curing a lack of phosphorus in the soil as well as sustaining the health of established turf and plants all year round.