Introduction
Poor quality well water often contains high levels of total salts, as well as elevated levels of sodium and bicarbonates. High levels of bicarbonate pull calcium out of solution, thus reducing the presence of calcium on soil exchange sites. Sodium then attaches to these soil exchange sites and drastically reduces the natural structure of soils. Poor soil structure results in very poor infiltration rates, poor drainage and accumulation of sodium and total salts in the root zone. This contributes to salinity stress on Poa annua putting greens.
The three objectives of this replicated field research trial are as follows:
1) to evaluate products at high label rates to determine if the products can be used safely on Poa annua putting greens,
2) to determine if these products dynamically enhance visual turf quality, and
3) to determine through soil testing whether these products reduce total soluble salts, EC, bicarbonate and sodium levels in putting green soil profiles.
Materials & Methods
The field trial was conducted on the Poa annua chipping green at Corral de Tierra Country Club located near Monterey, California. Over the last several years this green had exhibited symptoms of salt stress and localized dry spot during late summer. This pushup (native soil) putting green was mowed six days per week at a cutting height of 125/1000ths and irrigated to avoid moisture stress. Corral de Tierra Country Club is located in a coastal inland valley microclimate. Summer conditions are often characterized by early morning fog, mid morning clearing and warm sunny afternoons. The average maximum temperatures from May to September range from 67.5 to 74.5 ° F with occasional temperature spikes into the high 90’s. Nighttime minimum temperatures during this period range from 49.1 to 54.5 ° F. Winters are moderate with average maximum air temperatures ranging from 60.8 ° F to 63.1 ° F and nighttime low temperatures of 35.4 ° F to 40.5 ° F. Average yearly rainfall is 18 inches with a very high percentage of precipitation occurring during the winter months from November to March.
Applications of the products presented in Table 1 were deployed at the rates and schedule presented. The entire field plot received a three-minute irrigation after every application event and was flushed with a 40-minute irrigation cycle 24 hours after each application event.
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Individual treatment plots measured 5’ x 10’ with 24” aisle ways. Treatments were replicated four times in a randomized complete block design. A calibrated CO2 propelled spray system pressurized to 28 psi and equipped with 11004LP Tee-Jet nozzles applied treatments at a spray volume of 65 gallons per acre. The Open All treatment was deployed at a spray volume of 6.0 gallons per thousand square feet. A pacing watch was used for all spray applications to ensure the uniform and accurate delivery of all treatments. A shaker jar was used to uniformly apply granular products.
Prior to the first treatment deployment each check and treatment site was sampled to a depth of three inches (Photographs 1 and 2). A composite soil sample was taken on the day of the first application (8/21/04) and at the end of the trial (10/4/04) and sent to Servi-Tech, Inc. for analysis. Electrical conductivity (EC), soil volumetric readings and ratings for turf color; turf injury and turf quality were conducted day of the initial application and every two weeks thereafter for the duration of the trial. On site EC readings were recorded at a two-inch depth with the W.E.T. sensor manufactured by Dynamax Corporation (Houston, Texas). Three EC readings were recorded from each treatment plot and the average calculated. Day of application EC readings were used to establish a balanced randomization across all treatments and replications prior to the first treatment application.
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Turf color was rated utilizing a 0-10 scale with 0 representing no green color, 6 minimally acceptable green color and 10 very dark green color. Turf quality was rated on a 0-10 scale with 0 representing no live turf and the poorest surface quality possible, 6 minimally acceptable putting green quality and 10 perfect putting green conditions. Turf injury from treatment applications was rated on a 0-10 scale with 0 representing no injury, 3 the maximum level of acceptable injury and 10 dead turf. The severity index for localized dry spot was calculated by multiplying the percent damage in each plot (0-100 scale) by the severity of damage (0-10 turf injury scale). Data were summarized and statistically analyzed. Differences between means were determined via LSD.
Results and Discussion
Treatment Effects on Poa annua Color (Table 2) • Poa annua showed a statistically significant reduction in color versus the untreated check following a single application of Open All on one of eight rating dates (Table 2). Statistically significant results are presented in red highlights in all tables. This detrimental effect was short lived and did not influence the long-term color of the stand.
• Poa annua showed a statistically significant improvement in color versus the untreated check following a single application of Aqueduct plus Caltrisal and a single application of Calcium Complex plus Aqueduct on one of eight rating dates. This effect was short lived and did not influence the long-term color of the stand.
• None of the other products exhibited any statistically significant effect on Poa annua color throughout the course of the six-week field trial.
Treatment Effects on Poa annua Injury (Table 3) • Poa annua showed statistically significant and unacceptable levels of injury versus the untreated check following a single application of Open All on one of eight rating dates (8/23/04: one day after flushing of the first treatment). This effect was short lived and disappeared within seven days.
• Open All was deployed at a spray volume of six gallons per thousand square feet, irrigated with a high volume syringing nozzle for ten minutes immediately following application, and then flushed with a 40 minute irrigation cycle 24 hours after deployment. Despite these quantities of water, Open All still caused short-term discoloration of the Poa annua.
• None of the other products exhibited any statistically significant or dynamically visual injury levels to Poa annua throughout the course of the six-week field trial.
• Poa annua showed a statistically significant reduction in quality versus the check following a single application of Open All on one of eight rating dates (Table 4). This detrimental effect was short lived and did not influence the long-term quality of the stand. None of the other products exhibited any statistically significant reduction in Poa annua quality.
• Two weeks into the trial period temperatures soared into the high 90’s and low 100’s for several days at Corral de Tierra Country Club. These extreme temperatures resulted in the dynamic appearance of localized dry spot throughout the field plot. The appearance of localized dry spot provided yet another potential measure of value and benefit for the reviewed products and their treatment programs.
• As previously mentioned, damage from localized dry spot was calculated by multiplying the percent damage in each plot (0-100 scale) by the severity of damage (0-10 turf injury scale). Control was calculated through statistical comparisons to the untreated check.
• Specific treatments did show dynamic enhancement in Poa annua quality due to the prevention of localized dry spot when compared to the untreated check (Table 5). Although differences were not statistically significant, very strong treatment trends were observed.
• Those treatments that virtually eliminated localized dry spot included the following: Treatment #7, Calcium Complex Plus Aqueduct, Treatment #4, ECe-X plus Reservoir DG and Treatment #3, Aqueduct Plus Calsitrol. Open All also reduced localized dry spot.
• Those products that did not reduce localized dry spot to acceptable levels included Treatment #5, PBI Gordon Experimental #1, Treatment #6, Calcium Complex, and Treatment #8, Salt Exit.
Treatment Effects on Electrical Conductivity (Table 6) • On site EC readings were recorded at a two-inch depth with the W.E.T. sensor manufactured by Dynamax Corporation (Houston, Texas). Three EC readings were recorded from each treatment plot and the average calculated.
• Table 6 shows subtle differences in EC among treatments as recorded on eight evaluation dates over the course of the six-week field trial.
• All seven treatments performed better than the untreated check.
• The average EC for eight rating events and the corresponding ranking are presented in Table 6.
• Differences among treatments were not statistically different.
Treatment Effects and Soil Nutritional Analysis (Tables 7-15) • Results from treatment-by-treatment soil analyses as conducted by Servi-Tech Laboratory (Dodge City, Kansas) are presented in Table 7 though Table 15.
• Soil constituent levels are shown at the beginning of the trial (8/24/04) prior to the first application and at the end of the trial (10/4/04).
• Changes in constituent levels between the two testing dates are also presented. Key factors associated with salt management are highlighted in red.
• Data was generated from a composite treatment sample. One two-inch diameter core sample was collected to a depth of three inches from each plot. The core sample consisted of soil only. A composite sample for analysis was generated by combining one core sample from each treatment in each of four replications (e.g. 1 core sample per treatment x 4 replications = 4 core samples) and placing these samples in a one-gallon Ziplock bag.
• Even the untreated check plot showed a reduction in EC, sodium and total soluble salts over the six-week trial (Table 7). This undoubtedly shows the benefits of flushing events on push-up Poa annua putting greens even without supplemental product applications.
• Open All performed well within the realm of salt management. Those treatment plots treated with Open All showed a reduction in EC, sodium and total soluble salts. It would appear that Open All combined with leaching irrigations performed better than the check that received flushing alone.
• Although Aqueduct plus Caltrisal performed very well in preventing localized dry spot, this combination did not perform as well for salt management as some other treatments. However, EC, sodium and total soluble salts were reduced over the six-week trial.
• The combination of ECe-X and Reservoir DG resulted in a quality salt management program. Those treatment plots treated with this combination showed a reduction in EC, sodium and total soluble salts over the six-week trial. It would appear that the use of ECe-X and Reservoir DG in combination with deep leaching irrigations performed better than the untreated check plot.
• The PBI Gordon Experimental #1 product performed very well for salt management. Plots showed a sizeable reduction in EC, sodium and total soluble salts over the six-week trial. PBI Gordon Experimental #1 combined with deep leaching irrigations performed better than the untreated check plot that received flushing events alone.
• Calcium Complex treated plots exhibited a reduction in EC and sodium levels, but a slight increase in total soluble salts during the six-week trial.
• Calcium Complex plus Aqueduct contributed to a reduction in EC, sodium and total soluble salts over the six-week trial.
• Salt Exit appeared to perform very well for salt management. Plots showed a sizeable reduction in EC, sodium and total soluble salts over the six-week trial. Salt Exit combined with deep leaching irrigations performed better than the untreated check plot that received flushing events alone.
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• In this field trial the top four performing salt management products and programs were:
1. Treatment #5, PBI Gordon Experimental #1
2. Treatment #8, Salt Exit
3. Treatment #2, Open All
4. Treatment #4, ECe-X plus Reservoir DG
Summary and Practical Perspectives
From the data generated in this field trial located in the moderate climate of the Monterey Peninsula it would appear that some of the products that perform best for managing localized dry spot may be different than those that perform best for management of salts.
Successful management of localized dry spot was best achieved with products that contained wetting agents or soil moisturizing compounds. Those treatments included ECe-X plus Reservoir DG, Calcium Complex plus Aqueduct and Caltrisal plus Aqueduct.
While the concept of salt management programs is often thought to require a wetting agent or soil moisturizing compound to enhance movement of salts through the profile, the results of this trial have shown that as long as flushing irrigations follow treatment applications, products such as Open All, PBI Gordon Experimental #1 and Salt Exit can provide very effective reductions in EC, sodium and soluble salts in the root zone of a Poa annua putting green. However, some of these products exhibited very limited potential to reduce or eliminate localized dry spot.
Of the products reviewed, the multiple application program of ECe-X plus Reservoir DG exhibited the greatest potential to both reduce localized dry spot and contribute to salt management through reduction of EC, sodium and soluble salts.
In those common situations where management of localized dry spot and salt management is required a best management program rotating wetting agents or some type of soil moisturizing compound with technologies that are specific for sodium and salt reduction may be the best of both worlds.
The products reviewed are sound agronomic tools. The key to their successful use will depend on proper identification of the specific onsite problem.
Acknowledgements
A special thanks to P. J. Spellman, Rick Smith and the maintenance staff at Corral de Tierra Country Club for their cooperation and conscientious efforts in assisting with the soil sampling and the maintenance of the research plot.
Thanks also to Corral de Tierra Country Club, PBI Gordon Corporation, Helena Chemical Company, Deutrel Industries/Nu Science Corporation, Magic Green and Grigg Brothers for providing products and cooperative funding to support this field research trial.
