7 - Nutrient Management
Proper nutrient management is critical for maintaining healthy turf and an aesthetically pleasing surface for playability. The NMP indicates timing, amount, and form of nitrogen (N) and phosphorus (P), plus other nutrients that can be applied to an area based on soil properties, topography, land use, and proximity of fertilized areas to water bodies and groundwater resources. It provides education regarding site characteristics, environmentally sensitive areas, soil composition, fertilizer application rates, soil testing results and method, plus appropriate actions for spill response.
The appropriate application of essential nutrients allows turfgrass to recover from damage and player wear. Conditions such as drought, disease, and insect pests increase turfgrass stress – proper application of nutrients helps build turf resistance to these stressors. The goal of a proper nutrient management program should be to apply minimal nutrients to achieve an acceptable playing surface in the most efficient manner, helping the plant to recover from the stresses that it faces. Proper fertilization, in combination with other cultural practices, allows for sustainable turfgrass while reducing chemical inputs.
It is crucial to have an understanding of application rates and timing for effective use of applied nutrients at minimal environmental risk. Proper management helps prevent leaching or runoff in order to protect surface and groundwater resources. The State of Wisconsin has nutrient management regulations in place to protect water quality of these resources throughout the state.
A thoughtful and comprehensive nutrient management plan (NMP) is important for minimizing environmental risks and managing maintenance costs.
Regulatory Considerations
Wisconsin DNR administrative rule NR-151 requires NMPs for fertilized areas greater than five acres. Reference: https://docs.legis.wisconsin.gov/code/admin_code/nr/100/151
The turf portions of NR-151.10-15 and DNR Turf Nutrient Management Technical Standard (1100) provide current requirements and changes to the administrative rule. https://dnr.wi.gov/topic/stormwater/documents/dnr1100-turfnutrientmanagement.pdf
Reference NR-151 Rule Changes at https://dnr.wisconsin.gov/topic/Nonpoint/nr151Strategy.html
University of Wisconsin-Madison Turfgrass Science NMP checklist for compliance with DNR Technical Standard 1100 (NR-151.13(1)(b)3 and NR-151.14) https://turf.wisc.edu/2016/05/assistance-for-creating-a-nutrient-management-plan/
NR-151 video overview from University of Wisconsin-Madison Turfgrass Science: https://www.youtube.com/watch?v=RxzaF81j2Bk
University of Wisconsin-Madison Turfgrass Science DNR Turf Nutrient Management Technical Standard (1100) fact sheets: https://turf.webhosting.cals.wisc.edu/wp-content/uploads/sites/211/2016/05/NR-151-Fact-Sheets-All.pdf
Reference DATCP fertilizer certification and licensing regulations: https://datcp.wi.gov/Pages/Programs_Services/PesticidesFertilizersCertificationLicensing.aspx
Be sure to follow any additional local regulations and ensure BMPs are tailored to local requirements as needed
Best Management Practices
Comply with Federal requirements, Wisconsin NR-151, the DNR Turf Nutrient Management Technical Standard (1100), and any local regulations
Identify who will develop and implement the NMP; the nutrient management planner should be qualified with certification of professional management, a bachelor’s degree in turfgrass science or related field, or experience equivalent
Conduct a site analysis
Undergo soil tests, understand pH levels, conduct plant tissue sampling. Conduct a water analysis annually
Establish a written NMP incorporating five key components (site characteristics, site map, fertilizer application rates/restrictions, soil testing results/methods, and spill-response plan)
Comply with NR-151 requirements based on high-traffic areas, low traffic areas, and newly established turfgrass
Consult with University of Wisconsin-Madison Turfgrass Science for N application rate guidelines as needed beyond NR-151 guidelines
Identify and map surface water management areas and ground water management areas; follow DNR and University of Wisconsin-Madison Turfgrass Science nutrient management guidelines
Choose the appropriate spreader for a given fertilizer material; calibrate and conduct preventative maintenance on application equipment according to manufacturer’s recommendations; include dates of calibration and names of employees conducting calibration in the NMP
Incorporate a general fertilizer application schedule by area into the NMP showing the amounts of N and P to be applied during each month of the growing season
Incorporate an overview of routine procedures for establishment, overseeding, and re-establishment of turf areas into the NMP. (i.e., how divots are filled, or practice tees managed) Include timing and fertility practices for seeding
Understand the components of fertilizers, labels, and functions of each element
Apply nutrients when turfgrass is actively growing
Apply slow-release N fertilizers at appropriate time of year to maximize product release characteristics
Use light, frequent applications (spoon feeding) to provide consistent nutrition and minimize potential for leaching and runoff; alternatively many courses use light, frequent granular applications to meet their needs
Avoid applying fertilizers to soils that are at, or near, field capacity or following rain events that leave the soils wet
Do not apply fertilizer when the National Weather Service has issued a flood watch or if heavy rains are likely
Use caution when loading, applying, and storing nutrients; adhere to proper fertilizer storage, loading, and clean-up procedures
Communicate fertilizer spill-response plan regularly with employees and include in NMP
Keep accurate records of fertilization (including date, location, fertilizer applied, rates, grade, N source, % slow-release N, form, applicator) and include within NMP
Nutrient Management Plan (NMP)
A nutrient management plan should be established in written format and shared with all parties associated with management of the site. The NMP should consist of the following:
FIVE KEY COMPONENTS
A narrative description of the site (acres, location, fertilized acres, soil type, grass species, size of waterbodies, etc.) land use, turfgrass species, soil types, and areas which are environmentally sensitive
Site map with topography, land uses, soil test locations, environmentally sensitive areas, and surface water bodies
Application rates and restrictions for recommended fertilizers by land use designation and environmentally sensitive areas
Results and method used for soil testing
Fertilizer spill-response plan
Source and additional NMP information:
https://cdn.shopify.com/s/files/1/0145/8808/4272/files/A3876.pdf
University of Wisconsin-Madison Turfgrass Science resources for compliance with NR-151: assistance creating NMP, education, NMP template, and NMP checklist:
https://turf.wisc.edu/2016/05/assistance-for-creating-a-nutrient-management-plan/
University of Wisconsin-Madison Turfgrass Science video guidance for developing NMP:
https://www.youtube.com/watch?v=RxzaF81j2Bk
Site Analysis
The site analysis incorporates an understanding of land use, turfgrass species, soil types, and areas which are environmentally sensitive. The land use areas and environmentally sensitive areas should be mapped with topographical mapping, including indication of soil test locations and surface water bodies. The DNR recommends different fertility rates by land use designation. Three designated land use areas include: high-traffic areas, low traffic areas, and newly established turfgrass.
Three types of professional analysis are needed for the foundation of the NMP in order to ensure turfgrass health, performance, and recovery: soil, plant tissue, and water sampling.
Soil Sampling
The purpose of soil sampling is to provide a detailed report which includes measurable variables including pH, organic matter content, salinity, and nutrients available for plant use. It also offers a prediction of a plant’s response to applied nutrients. Proper use of testing results includes analysis, interpretation, and recommendations.
NR-151 requires fertilizers are applied based on appropriate soil tests. The DNR technical standard defines appropriate as each area that is managed differently, has a unique soil type, or displays obviously different turfgrass growth.
Take 10 to 15 random soil core samples from each area. Each sample should be from the same depth, a six-inch depth (or four-inch for golf greens and tees). Break the cores and mix them together in a clean plastic bucket, removing debris. Determine a labeling system and place two cups of the mixed soil in a labeled bag for the soil testing lab.
Select a laboratory which uses a nutrient extraction method appropriate for the soils. The Bray-1 and Mehlich-3 soil tests have been properly calibrated for turfgrass grown on native soil and sand-based root zones in Wisconsin. Both tests have been shown to provide reliable results for phosphorus and potassium.
Soil analysis combined with proper plant tissue sampling can provide the best picture of what is missing and what needs to be done to remediate the soil.
Best Management Practices
Accurate, consistent sampling is essential to providing useful information over any period of time
Divide course into measurable components based on DNR technical standard definition: areas managed differently, with unique soil types, or that display obviously different turfgrass growth
Take 10-15 samples from each area, break cores and blend together to get a uniform and representative mixture; place in a clean plastic bucket, removing debris; determine a labeling system, place two cups of the mixed soil in a labeled bag for the soil testing lab
Each soil sample should be taken at an equal depth; 6” depth or 4” for golf greens and tees
If the location has correlation data between a given nutrient applied to a soil and a response to that nutrient by turfgrass, then recommendations may provide expected results; if the location does not have correlation data, then soil test recommendations may be of little value
Use Bray-1 or Mehlich-3 soil tests and remain consistent in using extraction method when comparing test results from different periods of time
Soil test with a lab as approved by the University of Wisconsin
Keep soil tests from previous years for observation of changes over time to help make appropriate decisions in the future
Plant Tissue Analysis
Plant tissue analysis is valuable for helping to guide nutrient management decisions when used in conjunction with soil samples taken from the same areas. Clippings are analyzed for nutrient concentration in the plant. These values are compared to a critical level range indicating deficiency, sufficiency, or excess. Monitor the following for tissue analysis: turfgrass quality, clipping yield, and performance. Record and analyze these variables to help guide future nutrient management decisions. Two to four tests per year is common on greens and one to two tests per year on tees and fairways.
Best Management Practices
Tissue samples may be collected during regular mowing
Do not collect tissue after any event that may alter nutrient analysis
Place tissue in paper bags; do not use plastic
If possible, allow tissue samples to air dry before mailing them
Poor quality turfgrass that is of concern should be sampled separately from higher quality turfgrass
When turfgrass begins to show signs of nutrient stress, a sample should be collected immediately
More frequent tissue sampling allows more accurate assessment of turfgrass nutrient status and how it changes over time
The quantity of tissue analysis should be based on individual site needs; two to four site tests per year are common on greens while one to 2 tests per year are common on fairways and tees
Keeping tissue tests from previous years will allow for observation of changes over time
Tissue testing can provide good evidence of the impact of nutrient management programs
Water Sampling
The largest input to turfgrass is often water applied through irrigation. Impacts of water quality can have significant impacts on soil nutrients, soil structure, and nutrient availability. Water tests, along with soil sampling, will provide the greatest level of understanding to the proper ratios of applied nutrients required. Keep accurate records to show impact from the NMP. Managing a spreadsheet of sampling over time assists in understanding long-term impact on soil and plant health.
Reference Water Quality and Surface Water Management for additional BMPs.
Soil Properties Map
The University of Wisconsin-Madison Turfgrass Science has developed step-by-step guidance for obtaining maps of soil properties for the golf course NMP as required for compliance with NR-151:
Video guidance: https://www.youtube.com/watch?reload=9&v=7naJusJ_TYw
Document guidance: https://cdn.shopify.com/s/files/1/0145/8808/4272/files/A3876.pdf
Source for obtaining maps of soil properties: https://websoilsurvey.sc.egov.usda.gov/App/HomePage.htm
Surface Water and Groundwater Management Areas
The NMP must identify Type I and Type II surface water management areas (SWMAs). Type I are represented by areas on slopes within a specific distance from a lake or perennial stream or river. These are environmentally sensitive areas due to potential for runoff down the slopes. The following guidelines should be followed:
Water-soluble fertilizer should be used within Type 1 SWMAs
Fertilizers containing 50% or less slow-release N should be used
Indicate area on a map
Describe area including site, location, size, and restrictions in a table
Type II SWMAs are designed to protect areas within 20 feet of any navigable water, including intermittent streams that are navigable. The following guidelines should be followed:
Only liquid N and P may be applied, at a rate of no more than 2 lbs N/1000 ft2 annually
Drop spreaders can be utilized to apply granular fertilizer to putting greens and surrounds within 20 feet of a waterbody
Indicate area on a map
Describe area including site, location, size, and restrictions in a table
Groundwater management areas (GMAs) are designed to protect areas in which potential for groundwater contamination is relatively high. These exist where Hydrologic Group A2 soils occur, or where depth to water table is less than 12 inches, or depth to bedrock is less than 20 inches. This data may be found on soil survey maps. The following guidelines should be followed:
Fertilizers with at least 50 percent slow-release N should be used
Indicate area on a map
Describe area including site, location, size, and restrictions in a table.
Examples and assistance identifying SWMAs:
https://cdn.shopify.com/s/files/1/0145/8808/4272/files/A3876.pdf
High-traffic areas, low traffic areas, and newly established turfgrass
The DNR recommends different fertility rates based on land use designation. Three designated land use areas include: high-traffic areas, low traffic areas, and newly established turfgrass. These areas are recommended per the DNR Turf Nutrient Management Technical Standard (1100) guidance.
High Traffic Turfgrass Areas
High traffic turfgrass areas are defined as having more than ten users per acre per week and are regularly mowed and irrigated. Reference Table 1 for P applications by soil test interpretation and Table 2 for maximum annual N applications which vary by land use and soil type.
Low Traffic Turfgrass Areas
Low traffic turfgrass areas are defined as having fewer than ten users per acre per week and also include areas that are not mowed, regardless of use. Reference Table 3 for P applications. There are no land use or soil type adjustments for N and P guidelines for low traffic areas. N applications on low-traffic turfgrass areas should not exceed 4 lbs N/1000 sq ft annually when clippings are removed. When clippings are returned, not more than 3 lbs N/1000 sq ft should be applied unless the turf area is three years old (or less), in which case up to 4 lbs N/1000 sq ft may be applied.
Newly Established Turfgrass
The establishment period is identified as the 12-month period following seeding or installation of sod. If soil testing prior to establishment is not practical, apply no more than 1 lb N/1000 sq ft using a starter fertilizer and document why tests were not obtained. If a soil test is obtained, or if levels are known from a prior sampling, follow P guidelines as shown in Table 4. Note different interpretations for seeded and sodded areas.
Fertilizers Used in Golf Course Management
There are 17 nutrients essential for turfgrass growth. The components of fertilizers are important to understand in order to make informed decisions and appropriate applications. Nutrients are separated into two categories: macronutrients & micronutrients. Turfgrasses obtain oxygen, hydrogen, and carbon from the atmosphere and water, the remainder are obtained primarily through roots in the soil. (some may be obtained by foliar applications).
Macronutrients include nitrogen, carbon, oxygen, phosphorous, potassium, calcium, magnesium, and sulfur – these are required in relatively large amount.
Micronutrients such as iron, manganese, zinc, boron, molybdenum, copper, chlorine, and nickel are usually required in lower amounts.
Consult with University of Wisconsin-Madison Turfgrass Science for fertilizer sufficiency ranges in the location.
Macronutrients
Macronutrients are required in greater quantities and include Nitrogen (N), Phosphorous (P), & Potassium (K). Understanding the role of each of these macronutrients within the plant will provide you with a greater understanding of why these nutrients play such a key role in proper turf management.
The Role of Nitrogen
N is typically required in greater quantities by turfgrasses than any other element except carbon (C), hydrogen (H), and oxygen (O). N plays an important role in numerous plant functions including being an essential component of amino acids, proteins, and nucleic acids.
The goal of all applied nutrients is to maximize plant uptake while minimizing nutrient losses; understanding each process will increase ability to make sound management decisions and increase profitability while reducing environmental risk
To aid in this, understand the fate and transformation of N along with the release mechanisms and factors affecting N release from various N sources
Understanding how certain N sources should be blended and applied is essential. In many cases, N sources are applied without regard to how they are released. Each N source is unique and should be managed accordingly. Applying a polymer coated urea in the same manner as a sulfur coated urea greatly reduces the value of the polymer coated urea. Similarly, applying a 2 lb rate of N from an ammonium sulfate may cause burning but on the other hand, applying a 2 lb rate of a polymer coated urea may not yield the quick response of an ammonium sulfate urea. Rate, release curve, application date, location, seasonality, and turfgrass species should all be considered in the nutrient application decision.
Role of Phosphorous
Phosphorous (P) is essential for plant growth and is involved in the transfer of energy within the plant. The role of phosphorous is important in seed germination, seedling vigor, and rooting responses. It can be abundant in some soils and is a major contributor to eutrophication of water bodies. It should never be added to turf without a specific reason. Deficiency symptoms include slow growth and weak stunted plants. Initially, dark green color may be observed. Later, lower leaves may turn reddish at the tips and then the color may progress down the blades. Soil and tissue testing will be the best tools to arrive at requirements and sufficient application rates.
P fertilizer sources:
Diammonium phosphate
Concentrated super phosphate
Monoammonium phosphate
Natural organics
Role of Potassium
Potassium (K) is an essential element directly involved in maintaining the water status of the plant, turgor pressure of cells, and opening and closing of the stomata. K needs to be maintained at sufficient levels because of its major “health” influence strengthening the turf plant against the stresses of cold, heat, drought, disease, and traffic wear. K is a key driver of osmoregulation which has been documented to increase stress tolerance. It is very mobile in the plant, and soluble and mobile throughout the soil profile. Deficiency symptoms include interveinal yellowing of older leaves, plus rolling and burning of the leaf tip. Tissue concentrations of less than one percent are considered deficient.
K fertilizer sources:
Potassium sulfate
Potassium chloride
Potassium nitrate
Secondary Macronutrients
Secondary macronutrients are essential to plant function and are required in amounts less than N, P, and K, but more than micronutrients. These include calcium (Ca), magnesium (Mg), and sulfur (S). These elements can be vital when low quality water is applied as a water source.
Micronutrients
Micronutrients are as essential for proper turfgrass health as macronutrients, but in very small quantities compared to macronutrients. Micronutrients include (Fe), manganese (Mn), boron (B), copper (Cu), zinc (Zn), molybdenum (Mo), and chlorine (Cl).
Soil pH
Identifying and maintaining pH levels is important for turfgrass growth. Soil pH is the result of chemical reactions that take place in the soil and affect the degree of acidity or alkalinity of a soil solution. Nutrient availability, along with flora and fauna activities, are closely associated with soil pH.
The optimum soil pH for turfgrass in Wisconsin is in the range of 5.5 to 8.2. Kentucky bluegrass does best with a pH between 6.5 to 7.0 while ryegrass can tolerate a slightly lower pH. The soil pH is usually a function of precipitation in a region which induces more leaching of Ca, Mg, and K ions which are replaced with H and Al ions. Other factors that affect soil pH are parent material of the soil, organic matter content of the soil, and fertilizing practices. Nitrogen applications generally have an acidifying affect because of the release of H ions.
At extreme pH values, certain essential nutrients become less available, while others become more available leading to excessive availability. At highly acidic levels of pH, there is a decrease in microbial activity which can lead to decreased mineralization and decomposition of organic matter causing potential loss of favorable soil structure, and excessive thatch buildup.
Correcting Acidic Soils
When soil test shows an acidic soil, the following materials are most common:
Calcitic limestone- CaCO3
Dolomitic limestone- CaMg(CO3)2
Soil tests are the only way to determine if the turf soil requires lime. The rate required for liming materials is partly determined by soil texture. Soils with more clay and silt require more lime than sandier soils. Soils with higher organic matter content may also require more lime than a soil with a lower organic matter content. To increase soil pH, apply a liming material (calcium carbonate, calcium oxide, dolomitic limestone) that contains Ca and neutralize acidity.
Lime moves slowly through the soil profile at a rate of 0.5 inch to 1 inch per year. It may take two or more years for the lime to increase the pH of the root zone. Test soil every two years to determine pH and make corrective applications. It is important to apply corrective measures before pH drops too low. Fall applications are best as are applications during aeration to move lime more quickly into the root zone.
Correcting Soil Alkalinity
To lower soil pH, products containing elemental sulfur (calcium sulfate, magnesium sulfate, potassium sulfate) should be applied. It is critical to understand the site’s soil nutrient balance before making applications. Applications should be tailored to correct imbalances.
Best Management Practices
Maintain a pH in the range of 5.5 to 8.2 to optimize nutrient availability and reduce fertilizer requirements
To increase soil pH, apply a liming material (calcium carbonate, calcium oxide, dolomitic limestone) that contains Ca or Ca/Mg and neutralizes acidity
To lower soil pH, products containing Sulfur (S) should be applied
In some cases, utilizing injection pumps into irrigation water to address pH can be beneficial
Application & Management
Calibration & Equipment
Calibrating application equipment is necessary to accurately measure how much fertilizer is being applied. Calibration and preventative maintenance should be administered in accordance with manufacturer’s recommendations or when wear or damage is suspected. Sprayer and metering pumps on liquid systems need to be calibrated regularly. Proper calibration reduces environmental risk and improves cost savings. Include dates of calibration and names of employees conducting calibration in the NMP.
Choose the appropriate spreader for a given fertilizer material. Spreader types include walk-behind rotary, drop spreader, bulk rotary or pendulum type spreaders, and spray. For example, granular fertilizer is usually applied with a rotary spreader. When applying it near waterways, cart paths, or other non-target areas, always use a deflector shield to prevent inappropriate distribution. An example of the wrong spreader choice includes applying sulfur-coated urea through a drop spreader, this could damage its coating and lead to an application of soluble urea.
Foliar feeding and liquid fertilization (fertigation) involve the use of a soluble nutrient. Fewer total pounds are applied at any one time, nutrients are used more rapidly, and deficiencies are corrected in less time. Frequent “spoon feeding” is effective for avoiding accidental fertilizer losses to the environment while also reducing the potential for spikes or low growth rates that impact play, turf recovery, clipping yield, weed establishment, disease outbreaks, and aesthetics.
Area & Timing
Incorporate a general fertilizer application schedule by area into the NMP showing the amounts of N and P to be applied during each month of the growing season. Incorporate an overview of routine procedures for establishment, overseeding, and re-establishment of turf areas into the NMP. (i.e. how divots are filled, or practice tees managed) Include timing and fertility practices for seeding.
The reduced height-of-cut and excessive traffic damage on putting greens results in an increased need for growth prompting an increase in nutrition needs. Tees and landing areas often have higher fertility requirements than fairways and roughs because they suffer constant divot damage. Fairways and roughs often require fewer nutrient inputs because of increased height-of-cut, less damage, and clipping return.
Avoid applying fertilizer to soils that are at, or near, field capacity or following rain events that leave soils wet. Do not apply fertilizer when the National Weather Service has issued a flood warning or if heavy rains are likely.
Record-Keeping
Keep accurate records of fertilization (including date, location, fertilizer applied, rates, grade, N source, percentage of slow-release N, form, and applicator) and include within the NMP. Reference record-keeping example at https://cdn.shopify.com/s/files/1/0145/8808/4272/files/A3876.pdf
Storage & Transport
Proper fertilizer storage, loading, and clean-up are important to reduce environmental risk. Load fertilizer into application equipment away from wells or surface water bodies. If a hard surface pad is not available, a tarp can be spread to collect spillage. Clean up spilled material immediately and apply as fertilizer; keeping in mind that if using a granular fertilizer, spilled material could be contaminated with debris, and not sprayable. If fertilizer is deposited on cart paths, parking lots or other impervious surfaces, sweep the material onto the turf to be properly absorbed.
Overall Site Map
A comprehensive map should be included in the NMP which details the turfgrass area. It should include general fertilized areas, soil test locations, SWMAs, GMAs, and any other key areas on the site.
