Everything You Always Wanted to Know about Fertilizer
Fertilizer is rated by content (by % of weight) of three major ingredients; nitrogen, phosphorous, and potassium. They are listed on every package of fertilizer. Such as 10-10-10 or 35-3-5 (here 35% of the bag is nitrogen, 3 % is phosphorous and 5 % is potash or potassium; the other 57% of the bag is filler.
General purpose fertilizers are sold by the pound units rather than coverage. A 50# bag of fertilizer may only have 10 lbs. of fertilizer and the rest of the bag consists of a dirt filler to help spread the mixture over your yard. If the filler (dirt) is a different particle size than the nitrogen, the bag can settle with the smaller particles shifting to the bottom of the bag. When the cheap fertilizer is spread there will be uneven distribution depending on the amount of settling that has occurred.
Premium turf fertilizers also have different structural characteristics than your cheap agricultural fertilizers (8-8-8). Premium fertilizers are sold by coverage area rather than weight. Scott’s actually grinds up corn cobs because of how light they weigh and bonds the fertilizer components to them. This process produces a fertilizer with structural characteristics of uniform size and consistency resulting in a more even distribution.
Nitrogen (N)
Nitrogen is the most important and costliest compontet in any fetilizer. Grass plants are unable to take in (nitrogen) nutrients in solid form. They must first be dissolved, so they may be taken in by the roots. Fertilizer, therefore, releases, to become available to the plants, at a rate depending upon it solubility. There are four types of soluble nitrogen, which we classifiey by their release characteristics (how quickly they disolve and become available to the plant.
- Ammonia Nitrogen: This is an instant release nitrogen and is usually absorbed completely within 72 hours. It’s cheif advantage is that it is cheap to make. You must use caution with any fertilizer that is high in ammonia nitrogen because too heavy an application will burn or kill the plant. In essence if you apply too much, an ammonia chemical burn of the plant results
- Urea Nitrogen: This is a fast release form of nitrogen that is absorbed by the plant within the first few weeks of application. Guano or chicken poop is one common form of urea. Which is an organic source of nitrogen.
Note: These two nitrogen’s will give you a good quick boost to greening your lawn. They are also the ones that cause your lawn to burn.
- Water Soluble Nitrogen: This is a slow release nitrogen that acts as its name suggests, it breaks down on contact with water. This form of nitrogen has a synthetic coating that is dissolved by moisture over three to six weeks. The coating gives an extended realease characteristic to this form of nitrogen.
- Water Insoluble Nitrogen: This type of nitrogen has an even slower release characteristic than water soluble since synthetic coating is broken down only by heat and time. It normally takes four to eight weeks for this to occur. This is the most expensive type of nitrogen to make.
Water Soluble & Insoluble Nitrogens
Both water soluble and insoluble will take up to eight weeks to breakdown, thus the steady flow of nitrogen to the plant with no burning effect. This slow release or spoon feeding of a plant over a long period leads to better root development and much healthier plant. Generally the higher the content of water soluble & insoluble nitrogen the better the fertilizer and the higher the cost. These two types of nitrogen are usually only found in your premium fertilizers. Slow release builds healthier and deeper root systems which is critical for growing a good lawn in our area. We lose most of our grass in late July and August from the hot & dry conditions. A deeper root system allows the grass to get moisture from deeper in the soil. Cheaper ammonia nitrogen fertilizers have an opposite or “hay maker” effect where the fertilizer creates an immediate top greening only and does not lead to root development.
As your mom use to say, read the label! See what the breakdown of the nitrogen is the higher the content of water soluble and insoluble nitrogen the better the quality and value.
Phosphorous (P)
In grass plants and others, this is essential for root development. In other plants it will also aid in fruit development and flower blooms or bulbs. You will note that fertilizers that are label for flowers and vegetables will have a much higher phosphorous content. Phosphorous (Super Phosphate 0-46-0) can be bought separately to fertilize bulbs and flowers. Phosphorous or phosphate cannot burn or damage plants so you do not have to worry about over application of this nutriment.
Potassium/Potash (K)
In most plants this aids in promoting disease resistance and increases drought tolerance. It also helps give strength to limps and stems to help plants survive sever wind and thunderstorms.
Nitrogen is what makes the grass plants grow and become greener. Phosphorous is what stimulates root development. And potassium or potash promotes disease and drought tolerance.
Premium Fertilizers
A premium fertilizer is one that combines three or four types of nitrogen with different rates of solubility to give your lawn a continuous controlled feeding.
Fertilizers such as 8-8-8 are all ammonia nitrogen and are made for row crops like soybeans where you can use a 10 row spreader and apply the fertilizer every few weeks. This type of fertilizer when used on grass causes a immediate spurt of growth(you mow twice in one week) but its effect is gone within a week.
Cost Considerations of Premium Fertilizers
The actual cost of using a Premium Fertilizer needs to be examined. Many people make the mistake of looking at the cost per pound as a way to evaluate the price. 8-8-8 and other ammonia nitrogen blends are mixed with dirt to facilitate the spreading of the eight percent of the bag that is nitrogen. Premium Fertilizers use a light weight material such as vermiculite that the active part of the product is bonded to. The idea is to make the product light weight that you don’t have to bring a dump truck in order to get enough fertilizer to do a yard. Look at the coverage (5000 sq. ft. etc.) to get a better cost comparison in fertilizers between brands of fertilizer.
Lime
Liming is necessary since the predominate soil in the Piedmont Carolinas is clay. Clay is made up of extremely small particles which tend to bind or stick together. An extreme example of this is when the sun bakes the ground into a hard brick like surface. Lime has the effect of breaking apart or loosening the clay soil.
Lime is applied for two basic reasons: to reduce the soil acidity (raise the pH) and as a source of two very important plant nutrients, calcium and magnesium. When soils are too acidic, many important nutrients including nitrogen become less available (cannot be used or absorbed) to plants even thought they may be present in the soil. Other elements at low soil pH are so readily available that become toxic to
the plant. This is the case with aluminum. 
Lime is also an economical source of calcium and magnesium. Our soils are naturally low in both these nutrients. The soil in this area is predominantly clay so it usually takes more lime than what is normally called for. Soils around Mecklenburg County usually range from slightly acidic (pH of 6.0 to 6.8) to very acid (pH of 4.0 to 5.0). A one unit decrease in the pH number represents a 10 fold increase in soil acidity. Most of our soils, if they haven’t been limed, are in a range from 4.5 to 6.0. Some plants such as azalea , rhododendron, pine, and spruce grow best in a soil pH between 5.0 and 5.5. Most other plants grow best between 5.6 and 6.8 because nutrients are more available.
Factors which make soils acidic are leaching from rainfall and irrigation, decay of organic matter and application of fertilizers. If you fertilize regularly, you need to be liming regularly. At some point a dollar spent on lime is going to produce much better results in plant health and growth than another dollar spent on fertilization.
When To Lime?
The best way to find out is to have your soil tested. We have a soil test kit that you will learn how to use or we sell a soil test kits for home use. You can send a sample to the Extension Service in Raleigh for a free test, but takes approximately eight weeks for the results. As a rule of thumb it takes 40 lbs. per thousand square feet to raise the pH by one. Don’t apply at more than the 50 lbs. rate at any one time. Turning in lime, as in preparing a garden, is the best application method. Application in early winter will allow the lime to loosen the soil by a combination of chemical action and the mechanical action of freezing and thawing. Lime can be put out anytime of the year, even in the summer because it has no saltiness. Dolomitic lime is found in two basic forms-powdered and pelletized. They have the same liming effect. Pelletized lime is simply powdered lime formed into a pellet. Pelletized lime is a little more expensive, but a lot less messy to apply.
Helpful Hint: Always thoroughly wash there spreader and spray with a lubricant such as WD-40 since lime is highly corrosive and will cause any metal parts to quickly rust and greatly reduce the life of a spreader.
Lime and manure should not be applied together. The lime works chemically on the manure and the benefits are lost.
