Evaluating a fertility program from the ground up
March 17, 2016 By Mike Jiggens
GOLF clubs may have been using the same fertility programs for several years—and perhaps they have been working fine—but it’s good sometimes to step back and look at how things have been done and ponder if maybe there is a better way.
Such is the opinion of agronomist Dr. Eric Miltner of Koch Turf & Ornamental, who spoke to golf superintendents in December at the 27th annual professional turfgrass seminar in Waterloo, sponsored by Ontario Seed Company and Nutrite.
He said he respects the adage which suggests if something isn’t broken that there is no need to fix it, but added that because fertility is so critical to a golf course, the practice should be carefully scrutinized.
The No. 1 reason to fertilize, Miltner said, is to enhance plant health.
“If you don’t have healthy turf, what have you got? You probably don’t have a job.”
Aesthetics ranks only third on his list of the most important attributes of fertilizer. Next to plant health, playability must rank toward the top, he said, noting that speed and ball roll have been emphasized more over the past 10 to 15 years.
Fertilization, mowing and irrigation are the three primary cultural practices Miltner said he learned while in school while a fourth might be surface management or soil cultivation. Although superintendents spend much of their time controlling pests, he said that isn’t so much a primary practice as it is secondary because pest management can be performed through an adjustment of the three primary practices.
“That’s what IPM (integrated pest management) is all about.”
The three primary practices are an important consideration in establishing a management program.
“Fertilization—nutrition—is the building block for a lot of things.”
When fertilizing, there is a visible response in the plant with its colour. Growth rate is important, he said, because it relates to ball roll and clipping management.
“If your growth rate is faster than you can keep up with mowers, that’s no good and nobody wants to deal with that.”
Density, Miltner added, is equally key for playability.
Various stresses will challenge golf turf quality, including foot and cart traffic, divots, plant diseases and weeds.
“A fertilization program is really a key in all these things. It can be a base for managing a lot of different things that go on on the golf course. If we have all these nutrients in the soil, why do we have to fertilize?”
Fertilization is supplemental nutrition. Miltner said golf course superintendents are counting on what is already in their soil to provide the base of their nutritional needs, but they need to understand what is in the soil, what is available and how the plant gets to it. Fertilization is then used to supplement that.
He urged his audience to think about their fertility programs, starting with the soil itself.
“Take inventory of your property, understanding it.”
A superintendent may have been employed at the same golf course for the past 20 years and knows virtually every square inch of it, but someone who has been on the property only a year or two still has a lot to learn about the environment and everything there.
“It’s important to look at everything you’ve got in your tool box,” Miltner said, adding it takes years to learn about a property and its soils.
Geography and climate will dictate which plant species can and can’t be grown. Even within a common geographic area, a huge difference can exist between the species used. As an example, he cited two golf courses in a region of Washington State which had similar climates and weren’t located far apart from one another. But they had different courses of management because of the species grown at each location.
One course was planted to ryegrass but was transitioning to poa annua. The other course—Chambers Bay, site of the 2015 U.S. Open—was planted to fine fescue yet was also transitioning to poa. Because of the different turfgrass species, they had to be managed differently. The superintendent would have to learn an entire new way of doing things from one course to the other.
Miltner said it is important to understand the species grown as well as their requirements. Understanding the differences between species is apt to lead to vastly different fertility requirements.
Soil knowledge is equally important, he added. Differences in texture can contribute to compaction issues which impact playability and turf health. Heavy clay soils may have a greater cation exchange capacity yet may drain poorly.
The amount of organic matter in the soil will make a difference with cation exchange capacity, water-holding capacity and drainage.
Over the vast acreage of a golf course, that can change dramatically based on such things as location and grade. As the terrain on a golf course changes, there may be thinner topsoil and less organic matter in higher elevations while the topsoil may be deeper with better fertility characteristics in low-lying areas.
How well an irrigation system works and its location can impact the way a golf course is fertilized, Miltner said.
Several U.S. states have restricted phosphorus use on golf courses while others have imposed nitrogen restrictions. This has forced many courses in the United States to submit written best management practices for how they fertilize their golf courses.
“It’s getting pretty challenging in a lot of places.”
A superintendent’s budget and what is available to him will have an impact on his fertility program. There are also expectations from owners, managers and members about what needs to be done on the golf course while outside groups may be applying pressure toward the superintendent about what he might be doing to the environment.
“It’s a tough one, but one you can’t ignore. If people start asking questions, you need to be prepared how to answer those questions.”
Miltner said the superintendent should respond by saying he is educated and knows his science and understands where his nutrients are going and is able to account for the nutrients he is using.
Soil testing is important to determine the soil’s needs, he said, adding physical testing should be done in addition to testing for pH levels, salt, nutrients, exchange capacity and irrigation water quality.
“Get a feel for the physical nature of the soil on your golf course and especially those acres that are different and respond differently.”
He suggested taking a good look below the surface to detect clues about what might be happening. A soil probe should always be close at hand and sampling should be done from similar areas. Using the same lab for analysis is critical, he added.
“Every lab does things a little bit differently.”
Miltner suggested finding a good lab and sticking with it so that the analyses are consistent.
Keeping records is an effective quality check of a program, he said.
Miltner spoke about the 4R nutrient stewardship program which was initiated to educate activists, government regulators and the general public that turfgrass professionals are doing everything they can to manage nutrients responsibly. The public advocacy initiative was launched by the International Plant Nutritionists Institute, putting everything into simple terms anyone can understand.
The four Rs means using the right product at the right time at the right rate in the right place.
“There’s not just one right way to fertilize. There’s not just one right product. There are a lot of options and a lot of good ways to do it right.”
Miltner offered a refresher to his audience pertaining to nitrogen, phosphorus and potassium. Nitrogen is needed for chlorophyll which builds up in the plant, allowing it to green up. Amino acids are the building blocks for everything in the plant, he said, adding almost every amino acid contains nitrogen. Nitrogen is the element most efficient in soils relative to plant use.
Responses from the plant from nitrogen use include colour, increased density, shoot growth rate and an impact on pathogen activity. The increase in density which works to choke out weeds is a secondary effect.
Miltner said there are about nine U.S. states which have restricted phosphorus use on turf. Critics suggest the element is unnecessary for the plant, that it pollutes water and shouldn’t be used at all. It is, however, essential for energy transfer in the plant and that energy drives various kinds of cellular reaction.
“Phosphorus is incredibly necessary, and there’s no substitute for it.”
Root growth, especially during establishment, depends on phosphorus for cell division, he said. Phosphorus-deficient turf is characterized by a reddish-purple colour, but generally there is sufficient phosphorus in soils to supply turf. It is rare, he said, but does happen.
Spring and fall are the best times of the year to apply phosphorus, especially on cool season turf, when the plant is least stressed and is growing fastest and can better take it up. Phosphorus is fairly immobile in the soil and tends to stick around in spite of what many will claim.
Miltner warned to use caution with phosphorus in areas where there is surface water and around ponds.
Potassium is essential for regulating turgor pressure which is key in water management and how the plant uses water. Without adequate potassium fertilization to activate the guard cells which control the stomata, wilt can occur. It is also the nutrient for stress tolerance.
Spring and fall, when the plant is under the least amount of stress, is the best time for potassium application.
“Try to stay away from applying it in the summer. With plant stress, it’s not going to utilize it as well.”
It’s also an environmental concern that potassium could get into water, but it’s more of a concern of efficient nutrient use so as not to carelessly throw away fertilizer dollars. Polymer-coated fertilizer products will stick around better during the winter or in sandy soils or sand-based tees and greens.
Nitrogen is much more complicated than the other elements with more sources, including readily-available, and more options. Quick-release soluble sources include urea, ammonium sulfate and nitrate sources such as ammonium nitrate and potassium nitrate.
Urea, Miltner said, is a little different than ammonium sulfate or ammonium nitrate, but, from the standpoint of how it is used and the plant response, they share similarities. Urea releases quickly—usually within a week—but that may be generous, he said. When watered in and as soon as it dissolves into the soil, it becomes immediately available to the plant. The release normally occurs in a couple of days.
While the longevity of release is one thing, the longevity of plant response is another, Miltner said. If something releases over eight weeks, there will be a plant response of about 10 to 12 weeks. If urea releases in a couple of days, there will be two to four weeks’ response, depending on the conditions.
He said that although there are no problems with traditional readily-available sources, they don’t have enhanced efficiency. They work, but to be used efficiently, they must be applied at low rates and frequently. Many superintendents will use urea of another quick-release source in their spray tank, dissolve it and spray their greens at a low rate every week, every 10 days or every other week. It’s an efficient way to fertilize, he said, but when rates reach one-third to a half-pound, inefficiencies of loss will occur because there is more soluble nitrogen in the soil than the plant can use.
When there is more than the plant is able to use, leaching occurs as well as runoff and volatilization. Miltner said low rates applied frequently is ideal for spoon-feeding golf greens, but it can’t be done everywhere because of the high cost of labour associated with it.
Enhanced-efficiency products, such as stabilized nitrogen, “is the new kid on the block.” The technology has existed for decades in the agriculture market, but has only been around for turf use about the last 10 years.
Stabilized nitrogen has a nitrogen stabilizer added to it which doesn’t change the nature of the urea, but affects some of things happening in the soil and, in the end, holds the fertilizer as urea or as ammonium in the soil for a longer period of time, making it more plant-available.
The stabilizer blocks the urea to slow it down.
“By slowing it down, it decreases the amount lost to the atmosphere.”
Miltner said it is not knocked out completely and that there will still be some loss to volatilization, “but it knocks it back a long way.”
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