WinterTurf and Nutrient Management Research Update and Proposal for 2023

BY DR. KEVIN W. FRANK, PAYTON PERKINSON, AND ERIC GALBRAITH MICHIGAN STATE UNIVERSITY

I. Long-term nitrogen and phosphorus leaching

1. MTF funding is used for sampling costs and technical salary.

2. Grad students involved: Payton Perkinson – this is not Payton’s thesis research, but she will work with Eric Galbraith on plot maintenance and sample collection.

3. Research benefits turf managers concerned with environmental fate and fertilizer efficiency.

4. Project duration: indefinite, July 2023 marks 25 years of consecutive data collection, this is the longest running turfgrass leaching research in the world and I will continue to apply treatments and collect samples with no end date in mind.

5. Project Update

Since the summer of 1998 leachate samples have been collected from the monolith lysimeters at the HTRC and analyzed for nitrate-nitrogen. July 2022 marked the beginning of the 24th consecutive year of leachate collection and 32 years since turfgrass was established on the lysimeters. The high N rate of 5 lb. N/1000 ft.2/yr was applied in 1998 and concluded following the 2002 season. High levels of NO3-N leaching were measured from the high N rate from 1998-2002. In 2003 the high N rate was reduced from 5 to 4 N/1000 ft.2/yr, and subsequently leachate NO3-N concentrations declined over an approximately 15-year period. After 15 years of treating the high N rate at 4 lb. N/1000 ft.2/yr, in 2018 we reverted to applying urea at 5 lb. N/1000 ft.2/yr split over 5 applications to two of the lysimeters to determine if after an extended period of time the high N rate would once again result in high nitrate-nitrogen concentrations in leachate. The application dates were May 1, June 1, July 1, Aug. 1, and Sept. 1. The remaining two lysimeters were treated with urea at 2 lb. N/1000 ft.2/yr split over two applications on May 1 and Sept. 1. Phosphorus from triple superphosphate (20% P) was applied at two rates, 1 and 2 lb. P/1000 ft.2 split over two applications. The low and high phosphorus rates were applied to the lysimeters that receive the low and high N rates, respectively. The phosphorus application dates coincided with the nitrogen application dates on May 1 and Sept. 1. The turf was mowed at 3 in and clippings returned to the plots. Lysimeter percolate was collected regularly, volume measured, and a sub sample collected for NO3-N, NH4-N, and phosphorus (orthophosphate) analysis by the MSU Soil and Plant Nutrient Laboratory.

Leachate was collected from January through December in 2022. The mean NO3-N concentration in leachate for the low and high N rates was 0.86 and 5.72 ppm, respectively. Mean leachate concentration for the low and high N rate increased from 2021 by 0.5 and 3 ppm, respectively. After 5 years of the 5 lb. N rate, NO3-N concentration in leachate is increasing once again like how it increased in the early 2000’s. Orthophosphate was detected in leachate samples on 13 of the 75 sampling dates. All the other dates had levels so low that that lab reports the result as not detectable. Phosphorus leaching is not a risk from the sandy loam soil profile at the Hancock Turf Research Center.

This research will continue to measure nitrogen and phosphorus leaching in a continually managed turfgrass system and provide insight into whether or not fertilizer rates for mature turfgrass stands, such as lawns, golf course fairways and roughs need to be reduced to eliminate the potential for excessive nitrogen and phosphorus leaching.

Key Points

1. After five years of the high N rate, 5 lb. N/1000 ft.2/yr, applications mean annual nitrate-nitrogen concentrations have now increased to 5.7 ppm.

2. Dormant season leaching continues to be a point of concern for the high N rate application.

II. Evaluating the effects of soil test philosophies on creeping bentgrass and annual bluegrass (MLSN vs SLAN Research)

1. MTF Funding was used for soil sampling costs.

2. Grad students involved: Payton Perkinson, this is not Payton’s Master’s thesis research project, but she applied fertilizer and traffic treatments to the plots.

3. Research benefits turf managers by determining the effect of soil testing recommendations on turfgrass performance and soil nutrient levels.

4. Project duration: This project concluded in 2022. What we learned from this research will be used to begin a new nutrient/soil testing project in 2023.

5. Project Update

This research evaluates two methods of soil test interpretation and fertilizer recommendations, Sufficiency Level of Available Nutrients (SLAN) and Minimum Levels for Sustainable Nutrition (MLSN). SLAN is an established method for determining fertilizer recommendations based on soil test results. MLSN is a more recent method for determining fertilizer recommendations and when compared to SLAN recommends lower application rates of phosphorus and potassium.

Soils were sampled in the spring of 2022. Mehlich 3 soil test extractant was used to determine soil nutrient levels and nutrient recommendations were made according to the formulas used by the MSU Soil and Plant Nutrient Lab for the SLAN method and MLSN nutrient recommendations were determined from published MLSN formulas. The study has three treatments: (1) phosphorus and potassium applied according to MLSN guidelines; (2) phosphorus and potassium applied according to SLAN guidelines; and (3) nitrogen only treatment with no phosphorus or potassium added. The nitrogen source for all treatments is liquid urea. Treatments were applied on two blocks: Penn A-4 bentgrass (Agrostis stolonifera L.) and mix of Penncross creeping bentgrass and annual bluegrass (Poa annua). Half of the plots are trafficked three times a week. Data such as normalized difference vegetation index, turf color and quality are collected biweekly.

Key Point

1. Research objective is to determine the effect of phosphorus and potassium recommendations from two different soil testing theories on turfgrass performance and soil test levels.

2. Results after three years of treatments indicate few differences in turfgrass quality between the two soil testing theories but both had higher quality, color, and interestingly moss encroachment than the nitrogen only fertilized plots.

Photo: Color, quality, and moss infestation differences were evident between the plot fertilized with phosphorus and potassium compared to the plot fertilized with nitrogen only.

III. WinterTurf Research Projects

I serve as the MSU lead on the USDA SCRI grant “WinterTurf: A holistic approach to understanding the mechanisms and mitigating the effects of winter stress on turfgrasses in northern climates.” The grant was funded for 2021-2025. The MSU portion of the grant is $738,690 with my portion being approximately $200,000 over the 4 years of the grant. Most of my funding will be used for graduate student Payton Perkinson in years 1-2 and then I will have funding for an additional graduate student for years 3-4. In 2022 we conducted reestablishment studies in the spring, applied fertilizer treatments throughout the season for a study to assess the effect of different nutrient application rate and timing on snow mold incidence, and applied leaf mulching treatments in the fall to assess the effect on snow mold incidence for lawn height Kentucky bluegrass.

Monitoring Winter Conditions with Sensors on Michigan Golf Courses

The MTF Founders Society funded the purchase of six winterkill sensor packages in 2020. The sensor package was developed by scientists at the University of Minnesota. Six sensor packages were installed at golf courses in Michigan to monitor conditions during the winter of 2022-2023. This preliminary data collection is now part of the WinterTurf grant that was funded in the fall of 2021. Our ultimate objective is to be able to develop a low-cost sensor package that would allow golf course superintendents to monitor winter conditions in real time and make decisions for example on removing ice if necessary to prevent winterkill.

Winterkill Re-establishment

In the spring of 2022 reestablishment seeding research was conducted at MSU, University of Minnesota, University of Wisconsin, and Iowa State University. On three consecutive weeks in the spring of 2022 four creeping bentgrass cultivars and Two-Putt annual bluegrass were seeded into an existing putting green that was killed with glyphosate the previous fall. The bentgrass cultivars were Penncross, Declaration, Pure Distinction and A4. Previous seed germination research at the University of Minnesota found that some bentgrasses displayed high germination rates at low temperatures while others performed poorly. As a first step in our research we designed a study to compare bentgrass cultivars and Two-Putt annual bluegrass over three seeding dates in the spring in the field. We will answer the questions:

1) Do cultivars differ in establishment rate, especially in a cold spring

2) Should I seed early or wait until it warms up?

We had poor germination and establishment across all locations in 2022. In addition to unfavorable temperatures that are often typical of establishing following winterkill, we had considerable amounts of creeping bentgrass survive and reemerge following the glyphosate applications. To eliminate the confounding factor of bentgrass not being completely killed by glyphosate applications we stripped the turf off a green in the fall of 2022 so that this spring we will seed treatments into bare soil. these plots while there was no moss in the nitrogen only plots. Our next study will separate the effects of potassium and phosphorus in combination with nitrogen on turfgrass performance characteristics and possibly moss infestation over time.

V. Extension Activities

My appointment at MSU is split among extension (70%), research (20%), and teaching (10%). I am the turfgrass extension specialist for Michigan and have been the committee chair of the MSU Turf Team since 2009. I view my role as an extension specialist as a conduit to communicate recommendations and research to both industry professionals and the public. I communicate via written articles, presentations, interviews, emails to industry listserves, and social media using Twitter and Facebook.

IV. National Turfgrass Evaluation Program Trials

I managed 4 NTEP trials at MSU in 2022: Kentucky bluegrass, tall fescue, fine leaf fescue fairway traffic, and fine leaf fescue fairway height nitrogen rate trial. The results from these trials can be found at www.ntep.org 2022 was the last year of the Kentucky bluegrass test and 2023 will be the last year of the 2023 tall fescue test. I also manage a Kentucky bluegrass trial for the Alliance for Low Input Sustainable Turf (ALIST).

IV. Future Plans – Soil Testing/ Nutrient Applications Research

One of the results of the MLSN vs SLAN research was that both treatments had considerably better color and quality than the nitrogen only treatment. However, we also observed increased amounts of moss invasion in

Following over a year of virtual presentations due to Covid restrictions, 2022 returned to normal with numerous presentations throughout the state at conference and meetings. In 2022, I made presentations in Lansing, Mt. Pleasant, Novi, Traverse City, and Grand Rapids. I attend all the MiGCSA meetings to be a representative of MSU and provide informational updates on MSU and MTF activities and events. I continued to write and revise articles on turfgrass management for the MSUE news website throughout the year. I serve as a resource for the MSUE Lawn and Garden telephone hotline and for turfgrass questions submitted online or via email. I participate in weekly/biweekly conference calls during the growing season for the Consumer Horticulture extension group to provide turfgrass management updates and answer questions extension educators may be receiving.