Fertilizing the lawn helps make it healthy

The best turf grass will perform only as well as the lawn-management practices it receives. Correct and timely fertilization contributes to a healthy yard. Fertilization is important because it improves turf grass density, color, and health. A healthy, properly fertilized, dense turf grass resists weed invasion and is able to better tolerate heat, cold, drought and wear.

Turf grass plants require nitrogen (N), phosphorus (P), potassium (K) and 10 other mineral elements in the root-zone soil. Each of these mineral elements is required for plant growth, but most are normally found in sufficient amounts in local top-soils. Applications of N-containing fertilizers are particularly important because 1) N is the nutrient required in greatest amounts, 2) the level of N within turf grasses is correlated to plant quality (color and density) and vigor, and 3) plant-available N is restricted in most top-soils.

P and K are also required in relatively large quantities for healthy plant growth. However, their use in turf fertilization is not as frequent or as much as N because plant requirements for them are smaller, they remain in most soils for a longer period of time, and it is common to find these nutrients at adequate levels within our top-soils. P and K fertilizations should always be based on a soil test. Deficiencies should be corrected for optimal turf grass growth. Adding P and K above levels determined by a soil test is wasteful because there is little, if any, evidence that turf grass quality is enhanced.

Nitrogen, phosphorus and potassium are always needed during turf grass establishment, during the beginning of each growing season, and during periods when extra-hardy tissue development is needed.

The availability of mineral elements in the soil is influenced by soil pH (pH of 7 is neutral, below is acid, and above is alkaline). Most of our soils are alkaline. The 13 essential mineral elements are each most available between pH 6.0 and 6.5. A soil test is needed to determine soil pH and whether sulfur (to lower pH) applications are required.

I would suggest an application of a complete fertilizer in the spring to enhance root regeneration and one in the fall to enhance winter hardiness. Summer fertilizer applications are made with a straight N source.

(Lance Brower is the community, leadership, and economic development extension agent, Stutsman County office, NDSU Extension Service. Contact him at 252-9030 or email lance.brower@ ndsu.edu.)

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