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September 2010

What Fertilizer is Best for Zoysiagrass?

Sicc_zoysia_fwy Many of the finest turfgrass surfaces in Asia are zoysiagrass, from the fairways of Singapore Island Country Club’s New Course, shown here, to the fine lawns of the Manila American Cemetery and the putting greens at Wack Wack CC, to more than 80% of the golf courses in Japan — zoysia is the grass of choice. But do you know what type of fertilizer will produce the best results for zoysia? A recent research project by Patton et al.* in Arkansas compared urea with nitrate as nitrogen sources for four different zoysia varieties, fast-growing and slow-growing types of both Zoysia japonica and of Zoysia matrella.

In their summary paper from this experiment, entitled Zoysiagrass Growth as Influenced by Nitrogen Source in a Greenhouse Trial, they found that leaf and stem development was enhanced by urea more so than by nitrate, and urea as the nitrogen source also stimulated root growth more than did nitrate. In fact, the root growth and shoot growth was as much as 30% greater in plants fertilized with urea as the nitrogen source compared to the zoysia plants fertilized with nitrate as the nitrogen source.

Patton_arkansas_zoysia_nitrogen *Patton, A., J. Trappe, and A. Pompeiano. 2010. Zoysiagrass growth as influenced by nitrogen source in a greenhouse trial. Arkansas Turfgrass Report 2009, Ark. Ag. Exp. Stn. Res. Ser. 579:74-76.

At the Asian Turfgrass Center’s research facility near Bangkok, we used urea as the preponderant source of nitrogen over three years of research in both sand and soil rootzones, and we found that all of the zoysigrass varieties tested responded well to urea. The practical results of this research suggest that turfgrass managers should choose urea-based fertilizers for zoysiagrass whenever possible, particularly when the zoysia is grown in a sand rootzone.


Which is a Stronger Grass, Paspalum or Zoysia?

Abstract One of the most interesting research papers I have read in the past few years is this one, entitled "Spatial and Temporal Dynamics of the Weed Community in a Seashore Paspalum Turf," by Xie et al. from South China Agricultural University. With a title like that, I expected the article to explain what weeds were found in a seashore paspalum turf, where those weeds were, and when those weeds invaded. Were the weeds at the edge of the seashore paspalum area, or were they on a high spot, or in a low area with wet soil, or were the weeds particularly intense in their invasion at certain times of the year? The actual result of this experiment, however, was somewhat unexpected, and is less related to dynamics of a weed community in seashore paspalum than it is to the fitness of seashore paspalum as a turfgrass in Southeast Asia. And this is something that everyone involved in the maintenance of turfgrass in Asia should be aware of.

The experimental results published in Weed Science found that weeds emerged most frequently during the spring and summer at the experimental site at Guangzhou. No surprise there. But what is most surprising is this, and I quote from the researchers in their article: "the seashore paspalum turf has been naturally replaced by manilagrass." Manilagrass is Zoysia matrella.


The image above shows an area at the Asian Turfgrass Center's research facility that was planted to seashore paspalum and was maintained similar to a golf course fairway for three years, with regular fertilizer and irrigation applications and mowing every two days. During that time of regular maintenance, the paspalum grew fine. But in 2009, when we implemented a reduced maintenance program, with no irrigation and reduced frequency of mowing and reduced fertilization, the Salam seashore paspalum went dormant and in some areas was completely overtaken by other grasses, such as the manilagrass as shown above.

Based on what I have seen in Southeast Asia, seashore paspalum must be provided with enough fertilizer and water to maintain a steady growth rate. If the growth of seashore paspalum is allowed to slow, then it will tend to be invaded by bermudagrass, manilagrass, and other weeds. We commonly see this on golf courses, where bermudagrass that has somehow come onto the site will gradually overtake the seashore paspalum. And the research from Weed Science, and our observations at Thailand, show that manilagrass can overtake seashore paspalum as well.

If you are growing seashore paspalum in Southeast Asia, and if you want to keep this grass as the primary species over the long-term, then be vigilant in keeping other grasses out, and by all means maintain a steady growth rate on the seashore paspalum. Use sand topdressing as the primary means to control organic matter buildup and supplement that with coring and verticutting as needed. With extensive inputs, seashore paspalum will perform well in Southeast Asia. Without intensive maintenance, however, seashore paspalum does not persist and will be overgrown by bermudagrass, manilagrass, or other plants more suited to this growing environment.

Handheld or Backpack Sprayer Calibration

Sprayer_calibrate A session during a recent seminar at Indonesia was devoted to sprayer calibration, and particular attention was given to the calibration of large, riding sprayers. Backpack sprayers are often used in Asia, and these sprayers also require accurate calibration to avoid misapplications such as we see in this photo.

An excellent guide to hand sprayer calibration is available from Kansas State University, with the four page "Hand Sprayer Calibration Steps Worksheet" available for download. That guide, however, is in imperial units, so I offer this modification to the procedure.

As a general guideline, many products applied through a handheld or backpack sprayer will work best when applied using a spray volume of 40 to 80 mL per square meter. To find the application rate of a handheld sprayer, follow these four steps.
1. Measure an area nine square meters in area (3 meters by 3 meters) and mark the edges of this area.

2. Using a stopwatch, measure the amount of time it takes to spray this marked area, using the normal spraying speed and technique.

3. Now, using the same sprayer pressure, spray into a bucket or measuring cup for the same amount of time as it took to spray the nine square meters area. Measure the amount of liquid collected, in mL.

4. To find the spray volume in units of mL per square meter, divide the amount of liquid collected (in mL) by 9. To find the spray volume in units of L/ha, divide the amount of liquid collected (in mL) by 0.9.

Once you have the spray volume, you may decide to adjust the spraying technique so that the amount of liquid applied is in a more suitable range, and you can also determine exactly how much pesticide or fertilizer should be added to the spray tank in order to achieve the desired result.