by C.J. Brown
An explanation of lawn fertilizers, and what they do.
|As a lawn care professional, I've been asked many questions over the years. It always strikes me as odd that many people don't know any of the basics, before they ask questions about far more complex matters. For example, when my wife recently helped me pack for a fishing trip, she asked me what sort of clothes I would need, and whether or not I had a sufficient quantity of bug repellent. My fellow anglers will immediately see that she completely misunderstood the whole point of fishing, which is to drink large quantities of cheap beer while remaining absolutely motionless. In essence, she didn't understand the basics, so her offer to help had little value.
When it comes to caring for your lawn, many folks may know that they should fertilize, but really don't understand exactly what fertilizer is. This is what I mean by first learning the basics. Let's begin with a breakdown of human nutrition. While there are a large number of nutrients that we all need on a day-to-day basis (Vitamin C, Calcium, Caffeine, Fermented Hops, etc.), there are really only three MACRO-nutrients. These are the ones that we need in the largest quantities, and they are Protein, Fat, and Carbohydrates (which are all conveniently found in bacon double cheeseburgers with chili and onions). Now, keep in mind that these are not more important than vitamins, minerals, etc. They are simply needed in larger quantities.
Your lawn and your garden plants also have three MACRO-nutrients that need to be replenished on a regular basis, since the plants use so much of them. In the case of your lawn, these are Nitrogen, Phosphorus, and Potassium. The other nutrients (like zinc, boron, copper, etc.) are needed in such minuscule amounts, that adding more is generally unnecessary.
The Nitrogen provides dark green, lush foliar growth. The Phosphorus is essential for seed germination and strong roots. The Potassium regulates and assists in the absorption of other essential nutrients.
When you purchase a bag of fertilizer, it will always have a "grade" printed somewhere on the label. Often, this is hidden within the bright colors and a big label proclaiming "Dr. Joe's Super Spectacular Wonder Lawn Fertilizer." The grade is simply three numbers that tell you how much of each nutrient is in that particular fertilizer. These are always printed in the following order: Nitrogen-Phosphorus-Potassium. (N-P-K). So if a bag says 24-4-12, this means it is 24 percent Nitrogen, 4 percent Phosphorus, and 12 percent Potassium.
The next thing you need to calculate is the amount of Nitrogen (the first number, remember?) that you'll need to use. By applying one pound of N on 1,000 square feet, you'll give the lawn a good feeding and add a good amount of phosphorus and potassium as well. If the fertilizer grade is 20-6-12, then you'll need five pounds of fertilizer for every 1,000 square feet of your property, because 20 percent times five percent equals 100 percent. A fertilizer grade of 30-10-20 would require more like 3½ pounds of fertilizer per 1,000 square feet.
OK! You're all set now, right? Well, perhaps not. For example, the bacon double cheeseburger may actually have a smidge more fat than is actually needed in a mid-afternoon snack. I'll debate this with my nutrition conscious friends, but the fact remains that you need to balance nutrition to get optimal results. In order to do this precisely you would need to obtain soil tests, and then enter into a series of mathematical formulas that are normally reserved for calculating the daily interest on third world debt. Since we all have more important things to do during baseball season, I will give you the quick, imprecise method for picking a decent fertilizer.
I like to use a fertilizer that has a roughly 3-1-2 ratio. By this I mean that 15-5-10 is good. 15-4-11 is also close enough. 15-75-23 has a 113 percent nutrient count, which I don't think is possible, but you math teachers can let me know. Once you have your fertilizer, read the bag carefully for instructions on how much to use. Keep in mind that you would use twice as much "10-3-5" as you would "20-6-10."
If you have more specific questions, please feel free to e-mail me at TheLawnCoach@aol.com or Chris@teedandbrown.com . Now if you'll excuse me, it's time for my mid-afternoon snack.
Christopher J. Brown is a partner in TEED & BROWN, Lawn Care for Distinctive Homes, in Norwalk. Reach him at (203) 857-4271 or on the Web at www.TeedandBrown.com.