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Turf Science: More Green For Less Dough

By Erik Skindrud, LCN Editor

Professor Mike Henry applies nitrogen fertilizer to zoysiagrass near Irvine, Calif. Zoysia grows slow and requires less mowing than comparable varieties while displaying acceptable winter green, as seen here in January. (Limited amounts of fertilizer held keep the green; the left side of this test-plot has been kept fertilizer free.) Photos by Erik Skindrud

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New turfgrass varieties and maintenance practices produce durable green with less water and fertilizer. Read on, because it doesn't take a turf scientist to understand that this can save you and your business time and money.

Golf course managers don't see turfgrass the way landscape contractors do. On a golf course, never-ending green is the highest priority. Limits aren't placed on water, fertilizer, pesticidesor on a work crew's sweat and toil.

It's different for the contractor who plants turf and irrigation in residential and commercial settings. With most sites connected to municipal water supplies, property owners face fines if they go over irrigation limits. What's more, increasing numbers of property owners are leery about pesticides and fertilizer. Whether their concerns are justified or not, many homeowners would be pleased if you told them that you're keeping their lawn green organically that is, without artificial fertilizer or pesticides.


Conservation Means Money

Each one of these rectangular turf plots is divided lengthwise into halves receiving fertilizer and halves receiving no fertilizer. The difference nitrogen fertilizer makes is especially apparent in the tall fescue plot nearest the camera. The name of this ongoing University of California study is Winter Color Enhancement for New Warm Season Grasses. (Tall fescue, of course, is classed as a cool-season turf.)

At first glance, it might seem that forgoing traditional pesticides might mean more work for you and your crew. In fact, recent findings suggest that cutting back on water and fertilizer means that you can spend less time mowing, which can translate into reduced labor costs for you and your business.

Some of these results come from the University of California's agricultural test facility near Irvine, Calif. Over the past decade or so, turf scientists like Mike Henry, Vic Gibeault and Vincent Lazaneo have found that warm season turf varieties like hybrid Bermudagrass and zoysia do well with less fertilizer and water than is generally recommended. What's more, new types like buffalograss and paspalum perform well with limited water in arid areas across the South and West.

A Spectrum Care Landscape worker mows overseeded ryegrass in Southern California in January. A number of municipalities (Tustin, Calif. is seen here) employ landscape contractors to handle maintenance duties. The same crew handled the overseeding job in Octoberin March or April they will cut the grass short again to encourage warm-season turf to take over.

Another key finding is that Bermudagrass and zoysiadespite their warm-season reputationwill stay green long into the winter if temperatures generally stay above freezing. Adding a little fertilizer in fall and winter can go a long way to maintaining what the researchers call acceptable turf quality far into the winter months.

A lot of people ignore their turf in the fall and winter, because they think it's supposed to turn brown and go dormant, University of California researcher Mike Henry said. But if you continue your fertilization, you can enhance and maintain that good green color throughout the winter. In the warmer-winter regions, there are a lot of turfgrass types that hold pretty good winter color if they're maintained and fertilized.


Choose Your Turf

A team from Spectrum Care Landscape scalps and renovates a warm-season St. Augustine turf lawn before overseeding with annual rye in October. Within three weeks, the cool-season rye produces lush, green color that lasts until temperatures warm up in the spring.

Back in the 1970s, Prof. Henry was one of the first scientists to introduce seashore paspalum (Paspalum vaginatum) to the U.S. landscape industry. Well-known today, paspalum was one of a new generation of unconventional turf types that offer advantages over traditional varieties. With seashore paspalum, the advantage is salt tolerance and hardiness near ocean breezes.

Buffalograss is a North American native looks a lot like Bermudagrass, but that's where the similarity ends. Like its name implies, buffalograss is native to the arid prairies. The variety has some of the longest roots of any turf type, which enables it to get by with very little water.

Free-growing grasses like this are an increasingly-popular option that requires less water and no mowing. The spray nozzle at right is part of an irrigation system connected to a WeatherTrak controller.

As with other kinds of turf, a bit of knowledge about buffalograss can help save you and your customers money, Henry explained.

If you give buffalograss lots of water and, say, four pounds of active nitrogen per 1,000 square feet per year, you're going to be mowing a lot, and you're going to have lots of clippingsmaybe as much as tall fescue, the professor said. But what buffalograss lets you do is to drastically cut back on irrigationand not die. It will do quite well on 40 percent of the water fescue needs and still look greeneven at the height of summer.

Ryegrass variety is critical to successful overseeding. Be sure to choose an annual ryegrass strain (Gulf Annual Ryegrass from Oregon is shown here). Annual rye will die off and let underlying warm-season turf resume growth in the spring. Perennial rye, on the other hand, would continue to compete with the primary turf.

Zoysiagrass is another type that offers distinct advantages over more-used turf. Zoysia offers landscape professionals the chance to keep turf green with much-reduced amounts of fertilizer. With zoysiagrass, turf stays nicely green with as little as two pounds of nitrogen (pure fertilizer) per 1,000 square feet per year. To keep tall fescue green, you'd need close to six pounds applied at the same rate.

Another zoysiagrass advantage is a slow-growth rate. Compared to buffalograss, with the same amount of fertilizer and water, zoysia produces half the amount of clippingsand needs half the time to keep it trimmed.
That cuts down on labor tremendously, Henry said.

Old-fashioned steer manure is an economical way to get nitrogen and other nutrients to turfgrass. The pungent substance is especially useful for overseeding because it promotes good seed-soil contact. Note that overseeding is also a beneficial practice in spring, where it can help fill-in gaps. Growing from seed, of course, is easier in cooler, moister climates.


Barriers to Use

With those advantages, why don't we see zoysiagrass carpeting lawns across the South and West? The answer has something to do with tradition, and something to do with growth patterns. The slow-growth rate that limits mowing for zoysia lawns is a disadvantage when it comes to planting them. Even so, the variety can be established in warmer weather with success rates that compare favorably to Bermudagrass.

With buffalograss' exceptional drought-tolerance, why isn't it much more common? The answer is that the American native is a better choice in some areas than in others.

Carlos Orea and Ismael Vargas of Vargas Landscaping lay tall fescue sod during a December downpour in Fullerton, Calif. Keeping freshly-planted sod moist is the key to successful establishment. The irrigation emitters placed every three feet here are part of a drip-irrigation system manufactured by Southern California-based Jardinier Corp. Photo by Deniene Husted,

When buffalograss is planted in high rainfall areas or when it is irrigated and fertilized, bermudagrass and other weedy grasses invade a stand of buffalograss, Texas A & M University's Richard L. Duble writes. Buffalograss is best adapted to low rainfall areas (15 to 30 inches annually) or areas that receive thorough, but infrequent irrigation.

Also keep in mind that buffalograss does poorly in shaded sites or in sites that get heavy use. You won't see it on football or soccer fields anytime soon. Also, given artificial irrigation and nitrogen, bermudagrass and other more aggressive grasses will outgrow buffalograss.

One of several dozen drip system emitters is barely visible after the installation of the fescue lawn. Fescue is generally classed as a cool-season turfgrass and requires a higher irrigation rate than Bermudagrass or zoysia. The drip emitters, incidentally, are designed to be unharmed if nipped by a low-set lawnmower.


Remember Two Things

There are two things to remember when it comes to turf. One, it pays to do a little research before you choose your turf type for a project. You may do better (for you and your clients) with one of the newer kinds. (If you aren't sure, ask a horticulturist or a turf expert at a local university extension program.)

Second, you can reduce your fertilizer and irrigation totals significantly. If you know when and how much to apply, you can keep the grass green much longer into the winter season. And that's a win-win for you and your grass.

LCN Editor Erik Skindrud uses a drop spreader to apply nitrogen and pre-emergent herbicide to a Bermudagrass lawn in January. Pre-emergent herbicides can keep crab grass in check for an entire season, but the substance must be applied before seeds sprout in winter or early springdepending on climate zone.

Fertilizer Application: How Much and When.

The amount of fertilizer to apply depends on the fertilizer product (percent nitrogen and release rate), the square footage (area) of lawn, and the purpose the lawn serves (athletic field or low-traffic lawn).

At planting. Fertilize soil before planting seed, sod, plugs or stolons. A general recommendation for a preplant fertilizer for most California soils is to apply 12 pounds of ammonium phosphate-sulfate (16-20-0) per 1,000 square feet (6kg per 100 sq m), rototilled into the top 4 to 6 inches (10 to 15 cm) of soil.

Existing Lawns: Most mature lawns benefit from about 4 pounds of actual nitrogen per 1,000 square feet per year. Recent University of California research on grasses suited to low nitrogen and water applications (e.g., zoysiagrass and buffalograss) found that they could perform adequately with only 2 pounds per 1,000 square feet of actual nitrogen per year. Grass growing in light shade requires less fertilizer than grass growing in full sun. Turfgrasses under a grasscycling program need slightly less nitrogen; turfgrasses under heavy wear from foot traffic or sports require more nitrogen to encourage faster growth to repair damage.

Some turfgrass varieties offer better cold-season results than others. Mike Henry is standing on a plot of centipedegrass in this view. Hard freezes kill the leaves and young stolons of the variety, but the grass recovers as soon as temperatures climb. Sometimes called lazy-man's grass, centipedegrass has a slow-growth habit and needs infrequent mowing.

Generally, a maximum of 1 pound of actual nitrogen per 1,000 square feet should be applied at one time when using a soluble chemical fertilizer. Nitrogen is the major element, so it is the element that the application rate is based on. Also, nitrogen is the most soluble element and has the most potential for burning the grass if applied too heavily. Often, less than 1 pound of actual nitrogen can be applied, but 1/2 to 1 pound of actual nitrogen per 1,000 square feet at a time is the usual recommendation. Slow-release fertilizers can be safely applied at higher rates. See the product label for specific recommendations on rates an frequency of application; the frequency can range from every 6 to 8 weeks to as long as every 6 months.

A variety of aeration equipment is available and should be used regularly as part of an integrated turfgrass-management program. A properly aerated lawn will make the most of every fertilizer application. Aeration also promotes positive root growth and helps grass resist thatch build-up. Most lawn mowers come with attachments. Landscape contractors can use an array of available attachments from Ventrac that include blades, edges, excavators, slip scoops, terra rakes and V-blades. Other attachments for its 4000 and 7000 series include turbine blowers, trenchers, tough cuts, snow blowers, power rakes, mower decks, generators, brooms, blowers and Aera-vators. Photo: Kluge Rehabilitation Center, University of Virginia

Calculating application rates. To find out how much of a particular fertilizer is needed to supply 1 pound of actual nitrogen, simply divide 100 by the first number of the analysis shown on the bag. This will give you the number of pounds of the fertilizer you need to apply to 1,000 square feet of lawn area to supply 1 pound of actual nitrogen to the turf. For example, if the fertilizer analysis is 21-0-0, 100 divided by 21 = 4.76 pounds of fertilizer needed to apply 1 pound of actual nitrogen. (A similar calculation is performed for metric measurements.)

Source: J. Michael Henry, Victor A. Gibeault and Vincent F. Lazaneo, University of California, 2002.

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June 18, 2019, 8:37 am PDT

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