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LAWNS |
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KEY CONCEPTS
A. MowingC. Fertilization
1. Fertilizer ratios3. Timing of fertilizer applications
4. Combined fertilizer-herbicide products
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FERTILIZATION
Mowing and watering are widely accepted practices in lawn care. However, some people ignore fertilizing the lawn. This neglect may be motivated by a desire to save money or time. However, fertilization is necessary to maintain an attractive, healthy lawn. Fertilized lawns are more vigorous and result in better resistance to environmental stresses, weed invasion, disease infection and insect infestation.
Unnatural demands are placed on turfgrass plants. They are grown very close together, often in poor soil. There may be nearby shrubs and trees competing for nutrients. Grass clippings are regularly removed, when they should be returned to the soil to replenish nutrients. The three most important nutrients needed by turfgrass are nitrogen, phosphorous and potassium.
Nitrogen is the most important nutrient needed by turfgrasses. It promotes leaf growth and rich green color. It is, however, the element that most quickly leaves the soil. It is leached out of the soil with rain and supplemental watering. When nitrogen is lacking, growth slows and the grass becomes a pale, yellowish color. Heavy applications of nitrogen cause rapid growth and the need for frequent mowing. Unnecessarily rapid growth can promote undesirable thatch buildup. Fast-release nitrogen incorrectly applied can burn turfgrass.
Phosphorous promotes strong root growth and is especially important in the development of new lawns. Phosphorous does not readily move through the soil. Therefore, it is beneficial to apply phosphorus based on a soil test and work it into the top 3 to 6 inches of soil before planting a lawn.
Phosphorus is needed by grasses in small amounts. Therefore, most balanced lawn fertilizers contain a low percentage of phosphorous.
Potassium promotes hardiness, disease resistance and ability to recover from injury. This is particularly important in lawns that are subjected to heavy foot traffic. Fertilizers usually contain a small percentage of potassium. Potassium slowly leaches from soil.
Calcium, sulfur and magnesium are needed for healthy lawns. Calcium is normally present in soils in adequate amounts. If soil testing indicates the need for lime, dolomitic limestone supplies calcium and magnesium. Lawns that do not "green up" after nitrogen applications may have soil deficiencies of iron or sulfur.
Lime is needed when a soil test reveals a pH that is below 5.5. Grass will perform poorly in soil that is this acidic. Nutrients are unavailable to plants when the soil reaction is too acidic. Lime should be added based on soil test recommendation. Use only ground limestone, dolomitic lime or high-calcium lime on lawns.
Lime is not a substitute for fertilizers. It alters soil acidity so nutrientss may become more available to turfgrasses. A word of caution to those who would add lime without doing a soil test. Too much lime in soil can bind soil nutrients so they are unavailable for uptake by roots. Like phosphorus, lime moves through the soil very slowly.
Don't guess; take a soil test. Then choose a fertilizer recommended on the soil test results. Two main areas of concern when puchasing commercial fertilizers are type of nitrogen and nutrient ratio.
Carefully read the label for the type of nitrogen in the fertilizer. Products containing 30% to 50% slow-release nitrogen are recommended. Slow-release nitrogen is called "WIN" or water-insoluble nitrogen. It provides a steady supply of nitrogen over several weeks. "WSN" means water-soluble or fast-release nitrogen. It is readily available for quick greening when watered in. Better quality lawn fertilizers will contain both fast- and slow-release nitrogen for a combination of quick greening and even growth over time.
Fertilizer ratios best suited for established Ohio lawns are 3-1-2 or 5-1-2. These ratios are the percentage of nitrogen to phosphorous to potassium, (N-P-K). Numbers, such as 10-3-7 or 29-4-8, also indicate the percent by weight of each nutrient. These percentages are close to the desired ratios and would be suitable for use.
Be careful when applying fast-release nitrogen fertilizer or fertilizer with 20% or more nitrogen to avoid FERTILIZER BURN. These types can burn if application overlaps and if they are not watered in. Burn will occur if a granular fertilizer is applied to wet grass. Remember, apply fertilizer to a dry lawn, avoid overlapping, and water it into the soil.
Organic sources of nitrogen, except blood meal, are slow-release forms. Soil microbial activity releases the nitrogen in organic fertilizers. Reaction of turfgrasses to organic fertilizers is, therefore, slower.
TIMING OF FERTILIZER APPLICATIONS
Timing is important for even growth of turfgrass. A full application in late fall (October to mid-November) followed by a light application in April or May and late August to early September keeps the lawn green without excessive spurts of growth. When weather conditions are hot and dry, grass growth slows. Plants have much lower nutrient needs during summer and fertilizer need not be applied. To maintain a green appearance during summer, supplemental watering is recommended.
If there is only one opportunity to feed turfgrass, it should be in late fall. Research has shown that late-fall fertilizer applications are the most effective for healthy lawn development and appearance. Late-fall application, combined with light, spring and late-summer/early fall applications, results in excellent growth.
A suggested feeding schedule for Ohio lawn grasses follows:
COMBINED FERTILIZER-HERBICIDE PRODUCTS
There are several combination products on the market. They fertilize the lawn and kill weeds and are referred to as weed-and-feed products. Use them only when a weed problem has been identified and it is the correct time to control the weed and to apply fertilizer. Use of combination products without the presence of weeds, to be on the safe side, is wasteful and environmentally unsound.
It is important to know the growth cycles of weeds. Herbicides are most effective when the weed is young and actively growing. The best time for herbicide application may not be the best time to fertilize.
FERTILIZER SPREADERS AND APPLICATION RATES
The two commonly available ways to apply fertilizers are by drop spreader and broadcast spreader. These two spreader types are used for dry fertilizer products.
Drop spreaders require more passes across the lawn than broadcast types. Be careful to overlap wheels so stripes of unfed lawn do not appear. However, overlapping too much may result in overapplication or burning. In either case, uneven greening is the result.
Broadcast spreaders throw fertilizer over a wider area by a whirling wheel.They require fewer passes because each pass covers a much greater area. It is, therefore, easier to use broadcast spreaders on larger lawns. Check the width of the pass on pavement to determine how far to space passes.
Both types of spreaders have adjustable settings that correspond to application rates on fertilizer bags. Purchase fertilizer products that have a uniform size for uniform application. Be sure to shut off the spreader when approaching the end of a run and keep it closed while turning, backing up or stopping. Use a normal walking gait. This will produce an even dispersal. If spills do occur, gather up excess fertilizer and flood the area with water to avoid fertilizer burn.
A third method of fertilizer application is the hose-attached sprayer. These sprayers use liquid products. Accuracy of rate and evenness of application are sacrificed for ease of application. These products contain very dilute levels of nutrients and may require reapplication at two-week intervals until the recommended amount of nutrients is applied.
With any method chosen, it is important to read and carefully follow label directions.
MYTH: If some fertilizer is good, more must be better.
Heavy applications of fertilizer will result in excessive growth. You will need to mow more often. Excessive applications also increase susceptibility to certain lawn diseases, causing thatch buildup, and may injure or kill the grass. Too much fertilizer during periods of slow growth or dormancy can stress turfgrass. Lawn fertilizer applications should coincide with turfgrass growth.
MYTH: Combinations of fertilizer and herbicides get the job done faster and cheaper.
Fertilizers and herbicides should be applied when they are needed. Kentucky bluegrass grows faster during spring and fall, and fertilizer should be applied during these seasons. Herbicides should be used specifically for identified weed problems. If proper timing is ignored, combination products may have minimal effect.
MYTH: Nature takes care of its self; fertilizer is not needed.
Turfgrass needs a low level of supplemental nutrients. The lawn is not a natural environment. When clippings are collected, the soil is robbed of nutrients that should be recycled back into the soil. Most lawns are grown on compacted, urban soils that are not ideal for growth. Nutrient supplements in the form of fertilizer are needed.
MYTH: Plant food is plant food; if it is good for the roses and bushes, it should be good for the grass. All those numbers are too confusing.
Fertilizers are not plant food. Plants manufacture their food using nutrients as building blocks. Fertilizer contains nutrients. Fertilizers for lawns should not be used on flowers, vegetables or fruits unless those plants require a similar ratio of nutrients. Fertilizers for established lawns are high in nitrogen. When used on flowering plants, these products will produce lush foliage at the expense of flowers.
MYTH: All fertilizers contain the same chemicals, so use whatever is on sale or cheapest.
Lawn fertilizers should be selected according to season, whether or not the lawn is established or newly seeded. Lawn fertilizers should contain both slow- and fast-release nitrogen. The slow-release nitrogen should be 30% to 50% of the total nitrogen. This provides nitrogen for even, seasonal growth. The fast-release nitrogen is for quick greening. Quality fertilizers have uniform particle size for uniform application. Cheaper fertilizers have particles of variable size and often large particles that do not pass through a spreader.
MYTH: Organic fertilizers are better.
Most organic fertilizers are much less likely to burn plants. However, their nutrients are made available to plants through microbial activity which means slower release. Organic fertilizers are also more expensive and have lower N-P-K ratios.
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