Golf Course Secrets part 3

Attention: open in a new window. PrintE-mail

What you need to know about Fertilizer

There are a lot of misconceptions about fertilizers. It is widely thought that ammonium nitrate is the fertilizer of choice for all grass needs. Nothing could be further from the truth. As a matter of fact ammonium nitrate should only be used in specific application needs such as a pasture for feed or hay. This includes applications where an accelerated yield is desired. Besides, in today's world purchases of ammonium nitrate can be met with curious looks and purchases of large quantities require licensing. The formulation for ammonium nitrate is 33-0-0, and gained popularity from being a cheap source of nitrogen, the principle growth factor for grass. In addition to only containing nitrogen and not phosphorus or potassium, this source of fertilizer is acidic and can change the soil's ph by lowering it.
     The homeowner does not typically have a lot of ground to fertilize so cost should not be a major factor; as a matter of fact putting down a cheap fertilizer will actually cost you more in the long run. My purpose is not give you long detailed technical information about fertilizers, but to give you the basics to keep your lawn healthy.
     The 3 numbers on a fertilizer bag are for the three most important nutrients for grass. The first number is for nitrogen, second number is for phosphorus and the last number is for potassium. Very simply, the formulation you see on a bag of fertilizer can be viewed as percentages. If a bag of ammonium nitrate was a 100lb bag, it would contain 33lbs of nitrogen, 0lb of phosphorus and 0lb of potassium. A bag that says 6-12-12 would be 6lb of Nitrogen, 12lb of phosphorus and 12lb of potassium if it was in a 100lb bag. Fertilizer however comes usually in a 50lb bag or a 40lb bag. Therefore a 50lb bag of 6-12-12 would only have (half) or 3lb, 6lb and 6lb of actual nutrients. A forty pound bag would have (6*.40) or 2.4lb, (12*.40) or 4.8lb and the same for potassium. It is important to know how many pounds of each nutrient you are getting so you will know how much to apply. As a general rule, you want to put down 1lb of Nitrogen per thousand square feet. If you have a half acre yard, or approximately 22,000 square feet (there is 43,560 or 44,000 sq ft in an acre) you have 22 one thousand square ft. A 6-12-12 application bought in a 50 pound bag would take a little over 7 bags to put 1lb of nitrogen per thousand square feet. (Each bag has 3lb of nitrogen, 3 goes into 22 a little over 7 times). This would result in 1lb of nitrogen to be put down per thousand square feet, 2lb of phosphorus and 2lb of potassium. 6-12-12 is a starter fertilizer, most of the time you will be putting down a fertilizer that has more nitrogen than phosphorus and potassium.
     At this point you are probably wondering what formulation of fertilizer you should put out on your lawn. There are all kinds of fertilizer combinations to choose from. The answer depends. I know that's not the type of answer you are looking for. Before I lay out some general guidelines you need to understand what each nutrient does. I won't bore you with the complex details of what each function of the element does and how they interact with the other elements. 

      Nitrogen (N): This element is essential to photosynthesis of the plant (the process by which the plant makes food). It is important to the making of chlorophyll; this is what gives the grass its green color. Being the most important element for shoot growth, nitrogen give grass that deep green color and causes the grass to grow. Have you ever noticed that a good rain is so much better than watering your lawn? The main reason for this phenomenon is that the atmosphere contains nitrogen, a good lightening storm produces even more nitrogen, and the rain collects the nitrogen and brings it to the plant.
      Phosphorus (P): This element enhances root growth and plant hardiness. Phosphorus also aides by giving the plant protection from diseases.
      Potassium (K): Potassium is essential to the winter hardiness of the plant. It aides in the collection of carbohydrates, the form a plant uses for the storage of food. It also aides in reducing transpiration (water exiting the plant through the leaf blade). This allows the plant use water more efficiently and can cut down on the plant's water needs. Potassium also makes the grass more durable, (strengthens the leaf blade) enabling it to hold up better to traffic.

     From this information we can draw some general conclusions. If we are establishing new grass, or trying to promote root grown, a fertilizer that is high in P should be our choice. It's a good idea to put down a starter fertilizer in the spring. The formulation such as 6-12-12, or 3-6-6 etc would be a good choice. We are trying to stimulate the plants energy away from shoot growth and directing it to the roots. That is why we don't want a high amount of N.
     Going into the winter it's a good idea to minimize shoot growth and increase the plants ability to store food for the winter. A high level of K would be the fertilizer of choice. Examples are 10-10-20, 5-6-10 etc. A formulation with the last number (K) twice the amount any of the other number is what to look for. Storage of carbohydrates is important to winter hardiness and the more capacity the plant has to store food the better. This is why it's always a good idea to raise the cutting height which allows the plant to have increased capacity to store carbohydrates.
      As a general rule most fertilizer applications will require a high level of nitrogen and approximately a 2 to 1 ratio of K to P. Examples are: 24-6-12, 22-3-6 etc. It is not always easy to find these exact formulations, find something semi-close and use the calculations provided above to determine how much to buy and then put out.
     Unfortunately not all fertilizers are the same. Nitrogen commonly comes from a urea formulation, ammonium formulation, IBDU, Organics & sulfur coated urea. IBDU, Organic fertilizer and Sulfur coated urea are a slow release form of nitrogen. Urea and ammonium nitrate are cheaper and have a fast release of N. It is very common to have rapid growth after applying a fast release source of N. I have heard complaints on several occasions of people who applied ammonium nitrate then had to mow their yard every 3 days. I strongly recommend a slow release form on N for a lawn. It will cost 3 times as much than a straight ammonium or urea source but the benefit will greatly outweigh the cost. A slow release fertilizer will not only give you a controlled growth, but it will keep your lawn looking better longer. You won't hate fertilizing your lawn because you dread mowing every few days. I recommend a sulfur coated urea product; typically they will provide a slow release for 30, 60 or 90 days. Try your local co-op, they should have, or be able to get what you need.
      One last thing I want to mention, you will be wasting your money if your soil ph is not in the acceptable range. Consider the diagram below and look at N, P &K. 
                                                                               Ph Scale PH scale

     The fatter the line, the more the nutrient is available to the plant. For example, when your soil PH is under 6 and over 8 Phosphorus doesn't become very available to the plant. If your soil PH is under 5 or over 9, Nitrogen availability is greatly reduced. Most grasses perform well in PH conditions between 6.5 and 7.2. Usually, lawns suffer from low rather than high PH problems. When the PH is low, lime must be applied to bring the PH back up. In clay soils it would take 100 lb of lime to raise the Ph 1 full number. You can buy a soil PH tester; they range from strips at about $7 up to $100+, or have a soil sample done by a lab.
     I hope you find this information useful, good luck on putting your neighbors to shame by having the best looking lawn on the block.

© 2009 Falcon Ridge Golf Club  |  400 Summit Chase |  Cedar Grove, TN 38321  |  (731) 968-1212
Designed and Hosted by
1-2-1 Marketing