University of Kentucky HENV-402 College of Agriculture, Food and Environment Cooperative Extension Service Water Quality and Nutrient Management at Home Brad Lee, Suzette Walling, and Gregg Munshaw, Plant and Soil Sciences; and Rick Durham, Horticulture

ertilizers and other lawn amend- ments benefit the residential land- scapeF by providing or supplementing the essential nutrients for plant growth and maintenance. Commercial are commonly formulated based on three major nutrients: (N), phospho- rus (P), and potassium (K). Each nutrient plays an important role in plant develop- ment; however, improper application of fertilizers and amendments may increase the risk of non–point source of surface and ground waters. Nutrients and Algae Figure 1. A. Satelite image of a toxic Lake Erie algal bloom which resulted in In a balanced system, the major nutri- a “do not drink” advisory for Toledo’s drinking water system in August 2014. B. ents (N and P) contribute to soil health Photo of algae bloom in Lake Erie from a boat, July 2017. and plant growth. However, runoff of surplus nutrients (particularly P) to fresh- water bodies can result in eutrophica- tion, creating a nutrient rich water body for algae growth. This process can to hazardous or nuisance algal blooms (HNABs). These blooms may appear as Urban (Lawn & Garden) a green scum on the water surface or as

thick mats below the surface. (lbs. / acre) Large growths of algae (Figure 1) can decrease oxygen levels in water and 60 limit light to plants that provide food Soil Test P Test Soil and shelter for aquatic organisms, and Agriculture may produce toxins that are harmful to

aquatic and terrestrial organisms. Some 50 100 150 200 2 of the toxins are known to cause skin 19901 1995 2000 2005 2010 2015 irritation, rashes, or even more serious Year damage in humans and their pets. Natural P in Kentucky Figure 2. Average soil test P levels of approximately 1 million samples col- The amount of P in soils is strongly lected from urban and agricultural soils between 1990 and 2014. related to the naturally occurring amount in the soil’s parent material. For example, Kentucky farmers are knowledgeable their plants actually need. In addition, the limestone parent material from about the level of P in their soils and most many homeowners over apply which soils in the Bluegrass region form apply only when fertilizer is needed or because they do not know the amount is naturally high in phosphate. However, when fertilizer is affordable. However, in of nutrients needed nor do they realize there are other parts of the state, such the urban areas of Kentucky, landown- the concentration of nutrients within as the western Pennyrile region, where ers are much less knowledgeable about different fertilizer sources. This problem the limestone parent materials and soils soil nutrient levels and often apply P is compounded by marketing campaigns are naturally low in phosphate. Many fertilizer without knowing how much by fertilizer vendors suggesting that a

Cooperative Extension Service | Agriculture and Natural Resources | Family and Consumer Sciences | 4-H Youth Development | Community and Economic Development particular brand of fertilizer is required can pick up after our pets and keep the landscapes will need regular N fertiliza- for a successful lawn or garden. Soil test grass and leaves out of the storm sewer, tion to remain healthy. Nitrogen, when results over the past 25 years show that but how should we manage our applica- properly applied, encourages growth of most Kentucky urban soils already have tions of fertilizer and other plant nutrient small trees and aids in the maintenance more than enough P and no additional amendments responsibly? and appearance of large trees. Nitrogen applications are required. also promotes thick, lush green lawns The agricultural sector has responded What You Can Do at Home that can reduce weed populations by to government incentives and economic The goal is to optimize fertilizer ap- crowding them out. Unless a soil test drivers to reduce P applications, resulting plication–in other words, to promote indicates that P or K is required, only in soil P levels that have decreased over healthy plants without applying excess. apply N. time. However, results from home and The key to good lawn care practices is to Right Rate garden soil tests show the opposite trend, follow the Five Rs of nutrient manage- with soil P levels increasing over time ment. For most landscape situations, two N applications (recommended application (Figure 2). The high level of P in lawn and • Right source. Know what is in the fer- garden soils indicates that many of these tilizer bag and match it to plant needs. rate is 1 pound of actual N per 1,000 square feet) are adequate. Remember soils are at a high risk for P becoming • Right rate. Supply the right amount soluble, indicating a higher likelihood of of nutrients for plants. that the N rate on the bag is given as a percentage. A fertilizer bag labeled 44-0- P being transported downstream by run- • Right time. Apply when fertilizer will off. It is important that the urban sector be most beneficial for plants. 0 will have 44 percent N, so you only need apply about 2¼ pounds of fertilizer to reduce P applications to avoid increased • Right place. Apply fertilizers near risk to our lakes and streams. plants. 1,000 square feet of lawn to apply a pound of N. To calculate how many pounds of • Right price. Don’t pay for something Urban Sources and you don’t need. a fertilizer you would need to supply a Transport of Nutrients standard application, simply divide 100 Right Source by the N percent on the bag. For example, We all contribute to nutrient pollu- Fertilizers are plant nutrient supple- the fertilizer mentioned above contains tion. As consumers, we contribute to ments that are applied to soils. These soil 44 percent N. If we divide 100 by 44 we industrial nutrient pollution through amendments should only be applied to get 2.27. Applying 2.27 pounds of what’s , generation of soils that cannot provide adequate nu- in the bag will supply the lawn with one electricity, driving cars, and consump- trients for plant growth. Commercially pound of N. tion of agricultural goods, just to name prepared fertilizers have standardized a few activities. Nutrient pollution can Right Time labels to indicate the percent of the pri- also come from our yards in the form of mary nutrients, which are always listed in Fertilizing in the fall is the best time fertilizers and other lawn amendments, this order: N, P (indicated on the label as for cool-season lawns (fescue and blue- from pets, poorly maintained P2O5), and K (indicated as K2O). P and K grass), trees, and shrubs. The applications septic systems, and yard waste (e.g., are always expressed as oxides (P2O5 and should be split with the first application grass clippings). In urban environ- K2O), although neither P2O5 nor K2O are just as the trees are going dormant (leaves ments, nutrients are carried directly to present in fertilizers. Organic materials changing color) and the second applica- waterways by stormwater runoff. Recent also supply some levels of these nutrients tion six weeks later. Splitting the two N research shows that nutrients from lawn but will have more variable composition, applications six weeks apart will encour- fertilization and pet waste are the major depending on the source material (Table age greener turf in winter, less spring contributors to N and P in urban areas, 1). It is important to know the needs of mowing, less heat stress, and fewer weeds with P being the primary nutrient trans- your plants and what you are applying and disease. Ideally, you want to apply ported through stormwater runoff. We to avoid excess. However, most urban fertilizer applications just prior to rain or run the sprinklers for a few minutes after application. This minimizes the chance Table 1. Various organic amendments, their analysis, and the amount required to fertilize a lawn with 1 pound of actual nitrogen per 1,000 square feet. is included that the nutrients will burn the plants. for comparison. Perennial flowers will benefit from a Amount Needed for 1 lb split application in spring with the first Actual Nitrogen per 1000 application in early April when plants are Fertilizer Analysis (N-P-K) sq. ft. emerging and a second application six Cow Manure 0.5-0.3-0.5 200 weeks later. Annual flowers and warm- season grasses (zoysiagrass, bermudag- Cottonseed Meal 3-1-1 33 rass) should be fertilized at six-week Fish Pellets 7-7-2 14 intervals over the summer. Vegetable Kelp Meal 2-1-3 50 gardens should be fertilized at the time 6-2-0 17 of planting, either spring or later summer. Urea 46-0-0 2.2 Right Place not on the plant. Use water from a hose tional P or K is required, applying these Just as important as where to apply to wash fertilizer granules from plant leaf specialty lawn fertilizers will not benefit fertilizer is where not to apply it. If you and stem surfaces, but not so much water the lawn or garden and often simply lead are using a rotary fertilizer spreader, con- that the fertilizer is washed away from the to . If Kentucky lawns do sider attaching a piece of cardboard or soil surface. Never apply fertilizers within not require P or K, why would we pay for other device to the side of your spreader 10 feet of surface waters. these nutrients? A comparison of fertil- when applying near impervious surfaces, Right Price izer prices (per pound of N) is shown in drains, or water sources to deflect fertil- Table 2. izer only toward the lawn and to protect Fertilizers are often packaged with Based on the prices in Table 2, urea these areas (Figure 3). Despite best things that your lawn and landscape is the least expensive N source. Other efforts, occasionally fertilizer particles may not need. Further, advertisements products may contain only N (similar to will fall on impervious surfaces. In these on television show beautiful landscapes urea), but the N can be in both soluble cases, the fertilizer particles should be that were produced using various brands and slow-release forms. These products blown or brushed back into the lawn. of fertilizers. While there are some reduce environmental impact and plant For steep slopes, make sure the ap- benefits of specialty lawn fertilizers phytotoxicity by slowly releasing N over plied fertilizer falls on vegetated areas (reduced burn potential, small particle time. Slow-release N products cost more so it stays in place rather than rolling sizes, slow-release N), when it comes to than urea, but the benefit may be worth downhill. If you are applying fertilizer the plant, the only thing that matters is the additional cost. Other products that to established plants other than turf, it is that the required nutrients are available contain P and/or K are more expensive best to apply fertilizer near the plants but in the soil. If you are not soil testing, or and are only recommended when a soil if the soil test report states that no addi- test confirms P and K are needed. Testing Your Soil A soil test is a chemical analysis of your soil. The basic test provides infor- mation on the plant available content of the major (P and K) and minor (calcium, magnesium, ) nutrients in your soil as well as the soil pH. The process for collecting a soil sample for a soil test is simple. All you need are a shovel, garden trowel, or soil probe (avail- able for loan at your County Cooperative Extension office), a clean and dry bucket, and a soil sample bag. Before collecting your soil sample, assess your landscape and identify the major areas you want to sample such as the lawn, flower beds, or garden. Work by area and collect samples from several random locations, keeping Figure 3. Lawn fertilizer spreader with cardboard taped to one side to keep the soil from each area separate. Using fertilizer off of impervious surfaces such as a driveway, street or sidewalk. your shovel/trowel, insert the blade

Table 2. Various fertilizer sources and prices per pound of nitrogen (2018 Lexington, Kentucky prices). Price per Pound of Fertilizer Analysis (N-P-K) Bag Size (pounds) Price of Bag ($) Nitrogen ($) Urea 46-0-0 50 36.94 1.58 10-10-10 10-10-10 40 11.90 2.98 Nature Safe 8-5-5 50 32.50 8.13 Miracle-Gro All Purpose 24-8-16 4 8.99 9.36 Plant Food Miracle-Gro Water 36-0-6 5 14.99 8.33 Soluble Lawn Food Scotts Turf Builder Lawn 32-0-4 14 15.99 3.57 Food Milorganite 5-4-0 36 12.99 7.22 about 4 to 5 inches deep. Move the blade Remember • Right place. Fertilize only your lawn back about an inch and again insert it into • Right source. Get a soil test and apply or garden; do not spread fertilizer on the soil. Remove the turf and plant debris only what your lawn and garden need. concrete or near a waterway. at the top, and place the soil in the bucket. (Usually Kentucky urban lawns and • Right price. Price per pound of N If the soil is wet and difficult to mix, -al gardens do not need additional P or K.) can range widely. The least expensive low it to air dry for a day or two. Once • Right rate. A majority of lawns need source of N is currently urea (46-0-0). dry, mix the soil while breaking up large only two pounds of N per 1,000 square For more information about your home clods. Remove a large handful and place feet per year. and the environment, visit the University in the labeled soil test bag. Repeat this for • Right time. For cool-season lawns of Kentucky Environmental and Natural each area, resulting in a soil sample bag (including trees and shrubs), apply Resource Issues webpage at https://water. representative of each major area of the split applications of N in the fall; ca.uky.edu. landscape. warm-season grasses should have split For more information on how to collect applications of N in the summer. a soil test and other turfgrass management information, visit the University of Ken- tucky Turfgrass Science webpage: http:// www.uky.edu/Ag/ukturf/lawns.html.

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