Department of Soil&Crop Sciences

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Fertilization

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Fertilizer supplies essential nutrients to the grass plant for adequate growth and maintenance of plant functions. If you want to have a quality lawn then some fertilizer is key. Different turfgrass species require different amounts of fertilizer and they all need to have the fertilizer at a consistent rate - by this I mean don't put down all of the required fertilizer for the year at one time because the plants cannot use it all then and most of it will be lost to leaching or move off-site with rain or soil particles. The key is to supply adequate amounts of essential nutrients (we base our recommendations on nitrogen because it is needed in the highest quantities by grass plants) throughout the growing season from April through September in amounts that can be fully utilized by the turf.

Selecting the right fertilizer

Most fertilizers are similar and what you really need is nitrogen. You can shop around by finding the cheapest price per pound of nitrogen. When you look at a bag of fertilizer, there are three numbers separated by dashes, which is called the "analysis" of the fertilizer. It is actually a percentage of Nitrogen, Phosphorous, and Potassium, which are the three nutrients in highest demand by the grass plants. Nitrogen is the first number, then Phosphorous, then Potassium (N - P - K). You can compare the price per pound of nitrogen taking the first number (for example we'll use 15) and divide by 100 for the decimal equivalent of the percentage (0.15). Now multiply this by the total weight of the bag (40 pounds) for the number of pounds of nitrogen in the bag of fertilizer (0.15 X 40 = 6 pounds of nitrogen). Now take the total price for the bag of fertilizer and divide by the number of pounds of nitrogen to get price per pound of nitrogen ($15 price / 6 pounds N = $2.50 per pound of nitrogen). Compare with other bags of fertilizer.

Phosphorous and Potassium are also important and it would be very helpful to buy a fertilizer with some of these nutrients included, but you can use a product like ammonium sulfate (21 - 0 - 0) or urea (46 - 0 - 0) for most of your fertilizer needs unless a soil test report shows that the other two nutrients are low in your soil. In many Texas soils, phosphorous is already at high levels and adding more from your fertilizer could actually cause problems.

Refer to the above publications for more complete information.