consistent with the previous project, the Sand-Capped lawn plots continue to provide excellent rainfall retention (i.e., runoff mitigation), during the majority of rainfall events.
In terms of runoff quality analysis, samples for each runoff event have been collected, filtered, and frozen for future testing at the end of the project. Analysis of these samples was delayed slightly due to the retirement of our former water quality specialist, Dr. Aitkenhead-Peterson. Following this season, samples will be analyzed and provided in next year’s final report.
Figure 1. Total Runoff (L) and Cumulative Rainfall (mm) for each runoff event and total runoff (L) of all landscapes for each runoff event during the study period. Error bars represents standard error.
Greenhouse gas emissions including CO2 , N2 O, CH4 , and NH3 were monitored several times during 2021 using a
portable gas analyzer (Figure 2). Te first measurements were conducted on 7/28/21, which showed the background level of gaseous emissions prior to fertilization (of St. Augustinegrass lawn and Sand-Capped plots) and irrigation (of all plots). On 8/2/21, all turf plots were then fertilized at a rate of 1 lb. N per 1000 sq ft. [.454 kg. per 92.903 sq. m.]) using Scotts Turf Builder (32-0-10), plots were irrigated that evening (.5 inch [1.27 cm.] of water). Subsequent gas measurements were collected at one day (8/3/21), seven days (8/10/21), and 14 days (8/17/21) afterwards.
Figure 2. Measurement of gaseous emissions being taken for St. Augustinegrass Lawn plots during the Texas A&M landscape study.
Figure 3. CO2 Neither CH4 nor NH3 flux of each landscape type, measured prior to (7/28/21) and at one-day, seven-days, and
14-days after the 8/2/21 fertilization and irrigation event. Measurements were conducted in the morning on each day. Error bars represent standard error.
N2O are presented. Te CO2
were detected for any landscapes on any measurement date, and thus, only the results of CO2 flux appeared to be correlated primarily with the presence of plant biomass and associated
and
decomposing clippings/thatch, as well as the overall soil organic pool associated with a given landscape type. Te highest CO2
amounts of soil carbon and microbial activity (Figure 3). Even though the same plant palette was used for xeriscape and mulch, CO2
22
flux level was found for Sand-Capped Lawn and St. Augustinegrass Lawn treatments, which we attribute to greater flux was higher on Mulch compared to Xeriscape plots. Tis is likely to be related to the elevated amounts of
TPI Turf News September/October 2022
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