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Feeeding Your Lawn
The basic idea:
Clover may be a great natural fertilizer that you can grow amongst your grass – and it requires very little extra work. For another great inexpensive option, applying your own sieved compost is a great way to add nutrients and structure to your lawn. With organic fertilizers, you won’t be able to calculate exact amounts, but it has its benefits too. Or you can just use the conventional fertilizer.
Whether or not you need to apply anything other than nitrogen for a lawn depends on the ecological region in which you live: deserts require only nitrogen, rainier regions require nitrogen and small amounts of other nutrients.
For those who want to use fertilizer, but would rather avoid fertilizer rate calculations you can simply estimate the right amount of fertilizer with this suggestion: always err on the side of caution. You can always add more fertilizer but you can’t undo an application once the fertilizer has been spread. To reduce the risk of burning your lawn, even with compost, always start small and wait to see the results. Add more compost/fertilizer if the lawn doesn’t respond sufficiently to your desire, and once you’ve got good results make a note of that setting on your fertilizer spreader and increase the application rate any more.
The details:
Clover and Organic Matter The biggest fertilizer requirement for a healthy lawn is nitrogen. Nitrogen is what gives a lawn thick, rich growth and a nice deep green color. Nitrogen is, therefore, the major ingredient in the fertilizers used by commercial lawn fertilizing companies.
Depending on where you live, nitrogen may be the only supplemental fertilization your lawn requires; this is true for desert regions of the world. In contrast to rainier regions, desert soils are already full of most of the essential nutrients. The reason for this is because of the lack of rainfall. Since it rains so rarely, desert soils and all the nutrients in them never get washed or leached out. It is a well known fact that the soils of rain forests, by way of comparison, are some of the most barren in the world precisely because of the high volume of rainfall that washes through the soil, taking nutrients with it. All the nutrients in a rain forest are found in the plants themselves, not its soil. This is why tropical farmers burn rain forests to clear land for crops instead of harvesting the lumber to sell: they want all the nutrients left over in the ash from the burnt plants to go back into the soil.
Clover and grass: There is very little naturally-occurring nitrogen in soils across the world because most of the world’s nitrogen supply is tied up in the atmosphere as nitrogen gas, which is unavailable to turf. Very few plants can pull nitrogen out of the air (a process called “fixing nitrogen”). Legumes, like beans or clover, have the ability to do this, but turf, unfortunately, cannot. A lot of people want an immaculate lawn, with no weeds in it, but there is a natural option to fertilize your lawn, without you having to do anything! If you’re willing to put up with a bit of clover in your landscape, throw some clover seed around your lawn. The clover will pull nitrogen from the air and hold it in its plant structure – the roots, stems, and leaves. As naturally happens in any lawn or field, the clover will die, and new little clover plants will replace it. The clover that has died will then be decomposed, right next to the roots of your turf, and that nitrogen will naturally become available for your lawn.
Compost: If you have time and an amazing, well-broken-down compost pile, you have access to a great natural fertilizer. Compost generally contains tons of nutrients, as well as organic matter. It takes a little extra time, because to spread it evenly and not have big clumps sitting on top of your lawn (which would eventually kill that spot), you need to sieve your compost before spreading it on your lawn. Compost may not contain as much nitrogen as necessary. Nitrogen is one of the most elusive and hard-to-keep nutrients when it comes to plants and soil. So you may still want to add a little nitrogen using one of the two methods below. (But then again, you may not need to! It’ll all depend.) (See our articles on green and brown compost, as well as the article on organic matter, to learn even more.)
Organic fertilizers: Another option that is using organic matter, compost, or commercially-available organic fertilizers, which can provide great benefits to your lawn. If you’re going to make your own compost and use it on your lawn, you’ll need to sift it first to make sure you have a bucketful of fine compost. You don’t want to spread big clumps onto your lawn. Finely-sifted compost can be spread in much the same way as synthetic fertilizers, and they have several extra benefits: 1) They also add structure which allows for better drainage in clay soils and better nutrient- and water-holding capacity in sandy soils. 2) They are cheaper, if you produce them yourself or get the material for free. 3) They’re ‘organic’ and not synthetic. Synthetic fertilizers are technically a ‘salt’, which means that over time, your soil may become slightly salty, unless the excess synthetic fertilizer is washed through (yes, down to your ground water) where it won’t affect your plants. So even though organic fertilizers can’t be measured in the benefits they give or the exact amount of nutrients they add, and even though it may take a little more work to create your own compost pile and sift it and spread it, there are a lot of reasons why organic fertilizers are a great addition to your lawns.
Synthetic Fertilizers If you do choose to use synthetic fertilizers, its important to understand the chemical makeup of the fertilizers and a little bit about your soil so you can use fertilizers wisely on your lawn.
Photo credit: www.lawnsmith.co.uk
For the desert: if you live in a desert, nitrogen is all you’ll really need for your lawn; buying fertilizers with more nutrients than this is a waste of your money — the guy at the store selling you fertilizer won’t tell you that but it is true. Since it rarely rains in the desert their soils never get washed out, thus desert soils tend to be rather mineral rich. I’ve heard some people argue that the supplemental irrigation water used in desert areas also leaches soils like rain water in a rain forest. This is untrue. Rain water is fairly pure. Desert ground water, by contrast, is very hard, meaning it is full of minerals; thus desert irrigation water replaces nutrients just as much as it leaches them away. Some have also suggested supplementing with iron because sometimes iron deficiencies occur which can turn a lawn yellow. Again, this is a mistake for the desert dweller. There’s plenty of iron in a desert soil. The iron “deficiency” occurs from the iron not being available to the plants because the soil’s pH is too basic or alkaline, which is a common problem in desert soils (see the article on Understanding Soil pH). The way to solve this problem is to use a nitrogen fertilizer that is also chemically acidic. The best two nitrogen fertilizers (pictured below right) for a desert area are: urea (46-0-0), or ammonium sulfate (21-0-0). Both of these fertilizers supply only nitrogen and both are acidic.
For the rainier region: If you live in a rainier region of the world, your lawn will benefit from a fuller fertilizer that contains more nutrients than just nitrogen. Even so, in comparison to the amount of nitrogen you’ll need for your lawn, the amount of the other nutrients should be very small. Nitrogen is the biggie for lawns, then potassium, and then all the other nutrients in even smaller amounts. A good fertilizer composition for higher rainfall areas would be something like 35-1-10 or 26-0-8, where the first number represents the percentage of nitrogen, then phosphorus, and then potassium (N-P-K). The N-P-K numbers 35-1-10 and 26-0-8 I just came up with off the top of my head, but you get the basic idea: lots of nitrogen, very little or no phosphorus, and some potassium. All the other nutrients under nitrogen, phosphorus, and potassium, can be added and will help to replenish your soils supply of these nutrients since they may get leached out with all that rain. These nutrients are only needed in very small amounts, for example: 0.75% sulfur, 0.75% calcium, 0.50% magnesium, 0.25% iron, 0.10% zinc, 0.07% manganese, 0.05% copper . . . fractions of a percent for these elements. The percents of these micronutrients will be listed on the back of the fertilizer container underneath the N-P-K numbers.
Grass seed head.
A word about phosphorus: the reason why phosphorus has little importance in lawns (even though it is a major nutritional element in most plants) is because phosphorus is the nutrient that aids the most in flower/seed production. A lawn is always cut back and thus never goes to seed, nor do we want it to go to seed.We don’t want to grow grass seed – we just want the lawn itself. Phosphorus also aids in root development, but a lawn that’s been around for a couple of years or more already has a good root system by now. If your lawn is brand new then you can use a fertilizer with some phosphorus in it, otherwise use very little or no phosphorus at all. Your lawn doesn’t need it and it may also encourage broadleaf weeds in your lawn. The fertilizer pictured at right is a good example of a true lawn fertilizer. Notice how they actually advertise, front and center on the bag, for not having any phosphorus in their fertilizer (“phosphorus free”). They clearly understand that phosphorus has little or no function in a lawn.
A word about sulfur: turf does have a higher sulfur requirement than most plants because of its aggressive growing habit. Sulfur is used to create proteins that require unique three-dimensional structures such as enzymes made to fit specific bio-chemicals. Since turf grows vigorously it manufactures bio chemicals more frequently including protein thus using up more sulfur than other plants would normally use. For desert regions, using ammonium sulfate will easily satisfy the sulfur needs of your lawn. In rainier areas calcium sulfate or magnesium sulfate are probably your best choices. The calcium and magnesium are alkaline which will help neutralize the acidic soils of rainier regions. A calcium or magnesium sulfate application for the rainier area need only be applied once a year in early spring at a rate of less than one pound per 1,000 square feet of lawn (about 0.45 kgs per 93 square meters).
If you want to avoid the calculations, just estimate. But here are all the details for those of you who are interested to know.
How to calculate 1 pound of nitrogen per 1,000 sq. ft of lawn: Remember that the three numbers separated by dashes on your fertilizer bag (30-1-15, for example), represent percentages of nitrogen, phosphorus, and potassium respectively – percentages not pounds. So for my example fertilizer of 30-1-15 from above, the 30 represents 30% nitrogen not 30 pounds of nitrogen. In order to get the number of pounds of nitrogen instead of the percent nitrogen you need to multiply the nitrogen percent by the number of pounds of fertilizer in the entire bag. For example, a 40 pound bag of 30-1-15 has 12 pounds of nitrogen it: 0.30 (30% nitrogen) x 40 pounds of fertilizer = 12 pounds nitrogen. Done with metric units the calculation is as follows: 0.30 (30% nitrogen) x 18 kilograms (40 lbs) = 5.4 kilograms (12 lbs) of nitrogen. In order to calculate how much we’ll need of our 30-1-15 fertilizer to apply the recommended rate of 1 pound of nitrogen per 1,000 square feet we’ll need this equation:
(Your lawn surface area in square feet) x (1 lb nitrogen ÷ 1,000 sq ft) x (100 pounds of 30-1-15 fertilizer ÷ 30 pounds of nitrogen) x (1 bag of 30-1-15 fertilizer ÷ 40 pounds of 30-1-15 fertilizer) = the number of 40 pound bags of 30-1-15 fertilizer you’ll need in order to apply one pound of nitrogen per 1,000 sq ft of lawn.
If you do it with metric units of measure: (Your lawn surface are in square meters) x (0.45 kgs nitrogen ÷ 93 square meters) x (45 kgs of 30-1-15 ÷ 13.6 kgs of nitrogen) x (1 bag of 30-1-15 fertilizer ÷ 18 kilograms of 30-1-15 fertilizer) = the number of 18 kilogram bags of 30-1-15 fertilizer you’ll need in order to apply 0.45 kilograms per 93 square meters of lawn. This may seem complicated but it isn’t really.
Want to avoid calculations? Before I go on to more examples I should point out that there is a much easier way to fertilize a lawn than doing all this calculating: just estimate. You can always add more fertilizer but you can’t undo an application once the fertilizer has been spread. So experiment, but start small. If your initial light application of fertilizer doesn’t seem to perk up the lawn very much or the results are very short lived then increase the dose. Remember that it is always better to err on the side of caution then to over do it and burn your lawn, so once you’ve reached good results with a given rate of application don’t push your luck by continually upping the dose.
Check out the examples below . . .
Here’s a real life example using our 30-1-15 fertilizer: Let’s say your lawn is a quarter acre in size. One acre is 43,560 sq ft, so one quarter of that would be 10,890 sq ft (43,560 sq ft x 0.25 = 10,890 sq ft).
10,890 sq ft x (1 lb nitrogen ÷ 1,000 sq ft) x (100 lbs of 30-1-15 fertilizer ÷ 30 lbs of nitrogen) x (1 bag of 30-1-15 fertilizer ÷ 40 lbs of 30-1-15 fertilizer) = 0.91 bags or essentially one 40 pound bag of 30-1-15 fertilizer (always round up because you obviously can’t buy a fraction of a bag of fertilizer).
Written out in short hand, the math looks like this: 10,890 x (1 ÷ 1,000) x (100 ÷ 30) x (1 ÷ 40) = 0.91 bags (1 bag) of 30-1-15 fertilizer.
Here’s another example using ammonium sulfate (21-0-0):
Again, for simplicity sake, let’s use a lawn area of 10,890 sq ft.
10,890 sq ft x (1 lb nitrogen ÷ 1,000 sq ft) x (100 lbs of ammonium sulfate ÷ 21 lbs of nitrogen) x (1 bag of ammonium sulfate ÷ 20 lbs of ammonium sulfate) = 2.59 or three 20 pound bags of ammonium sulfate.
One final note: Remember that the 3 pounds of nitrogen per 1,000 sq ft of lawn (about 1.4 kgs per 93 sq meters) per growing season is regarded as the minimum requirement, not the maximum. You can definitely pamper your lawn by putting down more nitrogen than this. But remember, the maximum dose of nitrogen for each individual application should not exceed 1 pound of nitrogen per 1,000 sq ft (about 0.45 kgs 93 sq mtrs). If you add more than this, you risk burning your lawn. So, instead of having just three separate applications of 1 pound (0.45 kgs) of nitrogen to every 1,000 sq ft(~93 sq mtrs), you can have four or five applications in a growing season, just be sure to space them out. Or maybe you could have 10 separate applications of nitrogen per growing season but at a rate of ½ pound of nitrogen per 1,000 sq ft (about 0.23 kgs 93 sq mtrs) instead of 1 pound (0.45 kgs) nitrogen. Experiment . . . see what your lawn responds to best.
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