MANAGEMENT PRACTICES FOR
SMALL, MEDIUM, AND LARGE LAWNS
IN THE PACIFIC NORTHWEST
Lawns are ubiquitous in the Pacific Northwest. Lawns are always found in both urban and suburban environments. Lawns are also found on small farms throughout the region.
It is estimated that there are over 1,500,000 lawns in urban and suburban areas of the Pacific Northwest. These lawns range in size from a few thousand square feet on a small lot in Seattle to over 100 acres in a city park.
Lawns are also found in rural areas on small farms. Small farms range in size from 1 to 20 acres. There are approximately 12,000 small farms in Idaho, Oregon, and Washington. The number of small farms is growing rapidly and may double by the end of the decade. Since many small farms do not depend on crop and/or livestock receipts for the majority of income a significant portion of land is often covered by lawn.
A well maintained lawn is a source of pride. Homeowners often spend a lot of time and money ensuring that their lawn is healthy and beautiful. The well maintained lawn is an attractive part of the landscape, and adds value to any real estate property. In an urban setting the lawn ties together the home and landscaping. The lawn basically improves man's environment. It serves to moderate temperature extremes, reduce the impact of air pollution, and protects the soil by preventing erosion.
Many people apply pesticides and fertilizers to their lawns to keep them looking good. Wise chemical use is needed because poor management of chemicals may harm the environment. Chemical runoff and/or leaching from lawns may result in hurting both surface and groundwater quality. Because our underground sources of drinking water (aquifers) are often situated in areas where lawns are found, prudent chemical management is necessary to protect this resource.
The purpose of this slide set is to provide a background that will enable a homeowner and/or landowner to utilize best management practices that will allow him/her to produce a healthy, good looking lawn without negativley impacting the environment.
|1. Slide Title|
This slide set is entitled "Best management practices for small, medium, and large lawns in the Pacific Northwest." Funding for the development of this slide set was provided by a grant from the Pollution Prevention Program of EPA Region 10. Owners of small farms and suburban and urban dwellers that have lawns and utilize the best management practices introduced in this slide set will help protect both surface water and groundwater quality in the Pacific Northwest.
Your lawn is something you should be proud of! It is an attractive part of your landscape. In fact, a well-maintained lawn adds value to your property. Your lawn helps to tie your home and landscaping together.
|3. Lawns and the
A healthy, good looking lawn actually helps improve your living environment. On a hot day your lawn reduces the glare of the sun. Your lawn can also help keep surrounding areas cooler. A well-maintained lawn is much more attractive than pavement! Your lawn will attract birds and other wildlife. On windy days your lawn will trap dust particles from the air. And most importantly your lawn protects the soil on your property from erosion.
|4. Lawn Concept|
To protect the lawn and surrounding environment we use best management practices. The term best management practice is often shortened to BMP.
|5. BMP Concept|
Best management practices can be defined as implemented management strategies which eliminate or minimize environmental pollution. Extensive research has been conducted to design BMPs for both large and small areas of lawns. These practices can be used on lawns covering multiple acres or on lawns covering only a few thousand square feet.
|6. BMP Concept|
Best management practices have been designed to be compatible with healthy lawn management systems. Best management practices that you will see in this slide set can protect the environment without compromising the aesthetic quality of your lawn.
|7. Lawn BMPs|
This slide set contains BMPs for pest management and nutrient management. When you use the following BMPs you protect both the surface and groundwater quality of your local community. These BMPs will also provide you with a healthy lawn that is both safe and beautiful.
|8. Pesticide Concerns|
Why should you be concerned about pesticide use on your lawn? Well, many homeowners use more pesticides on a square foot basis than farmers do in large scale production agriculture. Unlike many farmers, most homeowners have not been exposed to education programs that teach the mechanics necessary to safely use and apply pesticides. Economics reduce the overall amounts of pesticides used on a large farm; however, economics are much less important on land parcels that are less than 10 acres in size.
|9. Pesticide Concerns|
Pesticide over-use will often harm or kill beneficial insects associated with your lawn. In addition, earthworms in your soil, birds, and pets can also be harmed or killed. Certain pesticides can also harm the applicator -- you -- if over-used or misapplied.
|10. Pesticide Concerns|
Pesticide over-use can harm your lawn and the surrounding environment. For instance, over-applications of pesticides may result in chemicals running off the surface of your lawn during rainfall or irrigation events. The pesticides in the runoff water could reach local streams, rivers, and/or lakes. On the other hand, some pesticides could leach through your soil and contaminate groundwater. This is the groundwater that is likely your source of drinking water. Over-application of pesticides may result in the accumulation of residues in the soil. These residues may be directly toxic to grass growth.
|11. Pesticide Concerns|
Over-application of pesticides will often result in pest resistance to the applied chemical. Naturally occurring mutations may create super insects or weeds which will be almost impossible for you to control with pesticides in the future.
|12. Common Lawn Pests|
There are many pests that attack lawns. These pests fall under four broad categories. These categories include weeds, insects, diseases, and other pests.
Weeds are simply plants growing in the wrong place. In the case of your lawn a weed is any plant that is not the variety of grass that was originally seeded to produce your lawn. There are over 30 weeds common to lawns in the Pacific Northwest. Most of these weeds can be easily eliminated from your lawn. Besides using pesticides, there are management options that discourage competition from weeds. Some options include mowing to the proper height, not over-fertilizing, and not over-watering. Chemicals applied to lawns that kill weeds are called herbicides.
Several dozen different insects live in your lawn at any one time. Most of these insects are harmless. In fact many insects are actually beneficial. These beneficial insects prey on insect pests that harm your lawn. Only a very few kinds of insects actually can damage your lawn. Chemicals applied to lawns to kill insects are called insecticides.
Lawns are susceptible to several different diseases. You need to remember that many of the diseases that attack lawns are caused by improper management by the landowner. Some potential management problems include improper watering, improper fertilization, lack of thatch removal, and choosing the wrong grass cultivar for the climate. Chemicals that are applied to lawns to control disease problems are usually called fungicides.
|16. Other Pests|
There are several categories of non-insect pests that attack lawns. These include rodents such as moles and gophers, nematodes, snails and slugs, and ants. Chemicals used to kill rodents are called rodenticides. Chemicals used to kill nematodes are called nematicides.
|17. Pest Management
There are five different BMPs that should be utilized on your lawn for effective and environmentally sound pest management. The first and most important pest management BMP is to know what is in your lawn. This is important for small, medium, and large-sized lawns. You should be familiar with the variety of grass you are growing. Know its growth characteristics. Identify the weeds in your lawn. Learn about common pests and diseases that may afflict your lawn. Identify your insect pests! Identify your lawn diseases!
How do you identify pest problems? First, observation is very important. Find the pest; note where it is found on your lawn; draw a picture or collect a sample. You have three alternatives for identifying the pest. First, you can buy a book, often called a key, with which you can match your pest to a photograph. Your second alternative is to take your collected sample to your local home and garden center for identification. Your third alternative is to contact your local Extension office. The Extension agent in your county can help with identification and provide advice to address your pest.
When a pest problem is identified, use the most environmentally sound solution! This BMP involves using a strategy which may be more labor intensive than using chemical or pesticide controls. For instance, it is more environmentally friendly to hand pull weeds in your lawn instead of using a herbicide. A change in water management may be an alternative to a fungicide for controlling a disease in your lawn.
|20. Correct Pesticide
If alternative solutions do not remedy your pest problems, pesticides may become a viable alternative. When used correctly, pesticides kill your pest and do minimal harm to other life in your lawn. Using pesticides correctly is a lawn BMP after the first two BMPs covered in this slide set have been evaluated for your lawn conditions. When using a pesticide you must read and follow the directions on the label of your pesticide container strictly.
|21. Pesticide Use|
To use pesticides correctly you must match the pesticide with your pest problem. Proper pest identification and following the label on your pesticide container are key points here. Use the correct pesticide application rate. Rates too high may harm beneficial insects, the lawn itself, and/or the environment. Buy only the amount of pesticide that you need. Excess chemical should not be stored for a long period of time.
|22. Storage and
Store and dispose of pesticides properly. Remember: you should buy chemicals in small quantities only -- so you won't have to worry about storage and disposal problems. If you have to store a leftover chemical, it should be placed in a secured area -- such as a cabinet that can be locked. Never store pesticides in your well pump house! When a chemical is no longer of use to you, dispose of it in the proper manner. Check federal, state, and local laws for proper disposal methods for your particular pesticide.
|23. Water Use|
The final pesticide management BMP is about water use. It is important to use water wisely on lawns. Pesticides in the soil move with water. Over-watering may cause the pesticide to leach. Leaching may cause groundwater contamination. Water management and pesticide management are closely related. You must do a superior job of each type of management to protect the environment.
Another group of chemicals that are extensively used on lawns are fertilizers. The terms fertilizers and nutrients are often interchanged. Why should you be concerned about fertilizer use on your lawn? Well, people apply large quantities of nutrients to their lawns. These nutrients can be applied as commercial inorganic fertilizers or as organic materials such as manures. Whether organic or inorganic, both types of materials supply a large quantity of plant nutrients to lawns. In fact, on a square footage basis, homeowners often apply more nutrients to lawns than farmers do to commercially grown crops in production agriculture.
The major problem with excessive use of fertilizers is the potential negative impact on the environment. Fertilizers can run off the soil surface and contaminate nearby rivers and lakes. Fertilizers also have the potential to contaminate groundwater when over-applied. The nitrogen applied to lawns is converted to nitrate by biological processes in the soil. Nitrate is mobile in soils and can leach into the groundwater. High levels of nitrates in water collected from wells can be hazardous to your health.
Over-fertilization is one of the primary causes of lawn problems. Nutrient over-use can result in poor plant health. The combination of large amounts of fertilizer, too much water, and water at the wrong time of day sets up the perfect environment for many turfgrass diseases. Diseases such as necrotic ring spot show up much more frequently in intensively managed, highly fertilized lawns.
Excessive fertilizer use may also result in excessive weed invasion. When given a nutrient-rich environment there are several weeds that become very competitive with the grasses you are trying to grow!
Lawns in the Pacific Northwest generally need additions of only four nutrients. These nutrients include nitrogen (N), phosphorus (P), potassium (K), and sulfur (S). If your soil pH exceeds 6.8 your lawn may also require additions of iron (Fe). Soils in the Pacific Northwest contain adequate levels of boron (B), chlorine (Cl), copper (Cu), manganese (Mn), molybdenum (Mo), nickel (Ni), and zinc (Zn) to meet your lawn's nutrient needs. Improper use of either nitrogen and phosphorus fertilizers on lawns can have a negative impact on water quality in your community.
|29. Nutrient BMPs|
There are four different BMPs that should be utilized for effective and environmentally sound nutrient management on your lawns. The first nutrient BMP encourages you to base fertilizer application rates on a sound scientific strategy. These two strategies are: soil testing strategy and nutrient ratio. Implementation of either strategy should ensure both a lawn that is healthy with the correct amount of plant nutrition and the protection of surface and groundwater quality.
|30. Soil Testing
The soil testing strategy bases lawn fertilization rates on a laboratory analysis of a soil sample collected from your lawn. This strategy consists of three steps: (1) taking the soil sample, (2) having the soil sample analyzed for its nutrient content, and (3) applying nutrients based on research data compiled by the regions three land grant universities -- Oregon State University, Washington State University, and the University of Idaho.
|31. Soil Sampling|
It is not difficult to get a good representative soil sample from your lawn. If you need information on how to take a soil sample contact your local county Extension office. Your soil sample should be collected early in the spring -- about one month before you plan to fertilizer your lawn. You can use a soil probe or shovel to collect the soil sample.
|32. Soil Sampling|
To get a representative sample of your soil in your lawn, take 12 to 15 subsamples to a depth of six to eight inches. Mix the subsamples together, and take a quart sample from the mixed sample. Make sure you exclude any surface debris that can change the soil test results, including grass blades. The more subsamples you take, the more representative your soil sample will be.
|33. Soil Sampling
This slide shows a recommended soil sampling pattern across a typical lawn. The dashed line shows a random walking pattern across the lawn. Soil samples should be collected at every spot marked with an X. A total of 15 subsamples would be collected from this example lawn. Based on this zigzag sampling pattern, samples would be collected from all areas of the lawn.
|34. Soil Analysis|
After collection, ship your quart of soil to a soil testing laboratory for analysis. There are several private commercial laboratories in the Pacific Northwest that can perform a soil analysis. In addition both Oregon State University and the University of Idaho will analyze soil samples. Your soil sample should be evaluated for pH, percent organic matter (% OM), phosphorus (P), potassium (K), and sulfur (S).
Fertilizer recommendations for your lawn will be based on this soil analysis. Percent organic matter is used to determine nitrogen needs. Soil P, K, and sulfate-S are used to determine fertilizer needs of P, K, and S, respectively.
Your nitrogen fertilizer recommendation for your lawn is based on the percent organic matter in your soil. Note that the nitrogen application rate in this table is per 1,000 square feet of lawn area. You can see from this table that the amounts of nitrogen required per 1,000 square feet range from 1 to 5 pounds. For example, if your soil test indicates that you have 2.4% organic matter in your soil, you would need to apply 4 pounds of nitrogen per 1,000 square feet of lawn. Based on research, this nitrogen fertilization rate should be adequate to produce a healthy green lawn, but conservative enough to protect the environment from excessive levels of soil nitrogen.
This chart will allow you to apply the correct rate of phosphorus to your lawn. As with nitrogen, the fertilizer rates are based on 1,000 square feet of lawn area. There are two common methods of determining soil phosphorus used in the Pacific Northwest. They are sodium bicarbonate and sodium acetate. Check your soil test report for the method used to determine phosphorus and use the appropriate column on this chart. For instance, if your soil test report indicated that your soil had 4.4 parts per million (ppm) phosphorus based on the NaHCO3 method you would apply 1 pound of P2O5 per 1,000 square feet of lawn area.
This potassium chart reads similar to the nitrogen and phosphorus data tables previously shown. A potassium soil test value of 120 parts per million would require a K2O addition of 2 pounds per 1,000 square feet of lawn area.
|39. Sulfur Requirement|
Soil samples testing less than 10 parts per million sulfate-sulfur require a sulfur addition of 1 pound per 1,000 square feet of lawn area. By using the N, P, K, and S charts in this slide set together with a soil test report you can make an excellent fertilizer recommendation for your lawn. This recommendation will adequately meet your lawn's nutrient requirements and protect water quality in your community.
|40. Nutrient Ratio
The nutrient ratio strategy is a viable alternative to using soil testing. In fact, this strategy is more widely used than soil testing. This strategy is scientifically sound and does not require the expense involved with soil analysis. In the nutrient ratio strategy no soil sample is taken. Instead the nitrogen application rate is based on the length of the lawn's growing season. After the nitrogen rate is determined, phosphorus, potassium, and sulfur rates are based on ratios to the nitrogen application rate.
|41. Growing Season|
To use the nutrient ratio strategy you must estimate the length of the growing season for your lawn. Basically, you determine the number of months of active grass growth. Do not count months where the average daily temperature is above 80 degrees unless the lawn is watered.
Let's do a sample problem to calculate the number of months of active lawn growth. This example problem calculates the time period for grass growth in Moscow, Idaho. In Moscow, grass starts to actively grow in mid-April. Growth often ceases by mid-October. In July and August temperatures usually exceed 80 degrees; however, supplemental water is added in Moscow during these months. So, we have active grass growth from mid-April all the way through mid-October -- a total of 6 months.
The nutrient ratio strategy suggests that 0.5 pounds of nitrogen are needed on a 1,000 square foot basis per month of active grass growth. If we use the Moscow, Idaho example where we had six months of active growth then we can calculate our total nitrogen fertilization requirement. Six months of active grass growth X 0.5 pounds N = 3.0 pounds of N needed. Consequently, 3.0 pounds of nitrogen are needed per 1,000 square feet of lawn area in our example.
|44. Nutrient Ratio|
Once you have determined the nitrogen need, phosphorus, potassium, and sulfur needs are based on a ratio to the nitrogen requirement. The currently accepted nutrient ratio for balanced nutrition in lawns is: three parts nitrogen, to one part phosphorus, to two parts potassium, to one part sulfur. This is often referred to as a 3:1:2:1 ratio.
Let's do another example problem. How much nitrogen, phosphorus, potassium, and sulfur do I need if my lawn is actively growing for six months per year? We already know how to do the nitrogen calculation - 0.5 pounds nitrogen per 1,000 square feet X 6 months is equal to 3.0 pounds of nitrogen per 1,000 square feet. Now using the 3:1:2:1 ratio we can determine the P, K, and S need. This would be 1 pound of phosphorus, 2 pounds of potassium, and 1 pound of sulfur per 1,000 square feet.
|46. Example (cont.)|
Now that our nutrient need has been determined we should go out and buy a lawn fertilizer with a nutrient content as close to a 3:1:2:1 N, P, K, S ratio as possible. Or, if we can not find a fertilizer with a close enough ratio we can mix several fertilizers together to obtain our desired nutrient analysis.
|47. Timing of Fertilizer Application
The second nutrient management BMP deals with the timing of fertilizer applications to your lawn. Timing of fertilizer application is important as it affects the efficiency of nitrogen and sulfur use by lawns. High efficiency will produce healthy green lawns and protect the environment. Conversely, poor efficiency often translates into either surface or groundwater pollution. The goal of this best management practice is to apply fertilizer at the time the lawn needs it most.
|48. Fertilizer Timing|
When the entire fertilizer requirement for the lawn is applied at one time efficiency is reduced and the environment is placed in jeopardy. You should use split applications on your lawn when you use either the soil testing or nutrient ratio fertilization strategy. Divide the total nutrient application required for the year by four and apply one quarter of the requirement in the early spring -- around Easter, one quarter in late spring -- around Memorial Day, one quarter in the late summer -- around Labor Day, and one-quarter in the fall -- around Halloween. The use of holidays makes it easier to remember when to make a split application. The fall application is made after grass growth has almost come to a halt; however, some nutrients will still be taken up by roots and the rest will be in the soil so the grass can get off to a good start when it breaks dormancy in the spring.
|49. Example Problem|
Let's do another sample problem. If your yearly requirement for nitrogen is 3 pounds per 1,000 square feet, using split applications, you would apply nutrients as follows: 0.75 pounds N around Easter, 0.75 pounds N around Memorial Day, 0.75 pounds N around Labor day, and 0.75 pounds N around Halloween. If you are using the nutrient ratio strategy you are also splitting portions of P, K, and S. If you are using the soil testing strategy you are splitting P, K, and S applications if your soil analysis indicated a nutrient need.
The third nutrient management BMP which can be used to protect the environment involves the use of slow-release fertilizers. Slow-release fertilizers improve nitrogen use efficiency by plants. Nutrients are released into the soil slowly over time. Consequently, nutrients become available to plants as they are needed. Slow-release fertilizers are environmentally friendly materials as they reduce the potential for leaching losses into groundwater.
Slow-release fertilizers should be used on many lawns. These materials have an environmental advantage on sandy soils and in situations where the grass is not growing rapidly -- such as in the early spring and late fall. If you are not going to split fertilizer applications, that is, you are only using one application of fertilizers per year you should make sure that you use slow-release fertilizers. Commercially, slow-release materials are referred to as WIN. WIN stands for water insoluble nitrogen. In slow-release materials the fertilizer is encapsulated and not readily available to the plant.
This slide shows the difference between a slow-release and a regular or quick-release nitrogen fertilizer. The slow-release fertilizer on the left is encapsulated. This coat may be made of elemental sulfur, plastic, or other materials. As microbes in the soil attack and create holes in the capsule, nitrogen fertilizer will slowly leak out. By varying the thickness of the capsule, manufacturers can control the rate of nitrogen release. On the other hand, a quick-release fertilizer granule is rapidly solubilized by soil moisture. All of the nitrogen is immediately available to the plant.
This slide shows what can happen if you add excess water to your lawn. In the case of the slow-release fertilizer the nitrogen that has already leaked out will be leached below grass roots. On the other hand, with the quick-release fertilizer, virtually all of the nitrogen is lost by leaching. The slow-release material will continue to leak nitrogen out into the soil -- providing adequate nitrogen for grass growth. It is easy to see which type of fertilzer is better for the environment!
|54. Water Management|
The final best management practice for nutrient use considers water management. You should use water wisely on lawns. Remember that nutrients in the soil move with water. Over-watering may cause nutrient leaching and result in environmental damage to your groundwater supply. If you apply excess water and you get runoff from the soil surface, nutrients may contaminate local rivers, streams, and/or lakes.
|55. Water Timing|
Lawns should be watered between 6 AM and noon. This timing is optimum because cooler weather discourages evaporation losses of water and there is less wind in the morning. Morning is better than night because of potential disease considerations.
|56. Depth of Water
It is better to water your lawn less frequently to the effective rooting depth of the grass than to apply small amounts of water every day. You should apply water to a depth of about six inches. There are plenty of roots at this depth to intercept plant nutrients. Watering to deeper depths may cause leaching of nutrients. Frequent shallow applications of water -- less than two inches of wet soil, encourage evaporation losses of water.
Remember, to protect the environment, your lawn management program must consider BMPs for pest management and nutrient management. Water management is a component of each. Utilization of the BMPs presented in this slide set will make you a steward of the environment. In most cases these BMPs will not increase your costs. In fact you will probably have a better looking, healthier lawn! Remember that your lawn management system can be environmentally friendly!
This slide script, WQ-23, was prepared by R. L. Mahler
and K. A. Loeffelman of the Soil Science Division, University of Idaho,
Moscow, Idaho 83844-2339.
This slide set and script was funded by a grant from the Pollution Prevention Program of the Environmental Protection Agency, Region 10.
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All contents copyright © 1997-2003. College of Agricultural and Life Sciences, University of Idaho. All rights reserved. Revised: January 3, 2003