Amending Soil with Compost to Reduce Stormwater Runoff and Lawn Fertilizer Use

Virginia’s Master Gardeners are Making a Difference In Water Quality One Yard at a Time

By Mike Goatley, Professor and Extension Turfgrass Specialist, Virginia Tech

Virginia is fortunate to have several very active Master Gardener Volunteer chapters across its major metropolitan areas.  The state has 62 MG units scattered across the Commonwealth comprised of over 5500 MGVs that made approximately ½ a million contacts in 2014.   These volunteers are organized and led by Virginia Cooperative Extension agents at the county and city levels and they receive extensive training in all areas of horticulture and soil science prior to their ‘graduation’ and designation as a Master Gardener Volunteer through VCE.  Their commitment also includes specified hours of volunteering in civic horticulture.  I have the privilege to provide the turfgrass component of their training for many of the MGV chapters and I consider these volunteers to be my ‘boots on the ground’ to spread the word regarding Best Management Practices in lawn care.

The Chesapeake Bay TMDL program has spurred the interest of many of the MGV chapters to develop committees specifically devoted to urban nutrient management activities.  These MGVs work with homeowners one-on-one, measuring their property, taking soil samples, and then meeting with the homeowner and discussing soil test results and a fertilization program that will result in a healthy lawn that protects the environment, not harms it.  Within the past year all of the urban nutrient management programs were merged under a statewide umbrella program called “Healthy Virginia Lawns”, an effort that will allow for better reporting and documentation of the impact that the Master Gardener Volunteers are making in improving water quality.

There is great interest in the use of microclover as a component of lawns in Virginia.  Research updates from Virginia, Maryland, and Pennsylvania were shared in MGV training programs I conducted for 10 MGV chapters and approximately 400 volunteers across the most populated counties in northern Virginia, Richmond, and Tidewater.  The constant question was ‘Where do I get microclover?”.  There still are some issues in exactly where microclover will thrive in Virginia because the Virginia Tech research at two comparatively warm locations in the state (Amherst and Virginia Beach) provided very mixed results in microclover persistence.  It appears that microclover persistence is going to be a challenge in our warmest regions.  However, microclover has performed very well either as a monoculture or in a mixture with tall fescue in Blacksburg at the Virginia Tech Turfgrass Research Center.  It is anticipated that microclover will thrive in the cooler areas of Virginia, particularly the highly populated northern Virginia locations that are much closer to the University of Maryland research site than the warmer research locations where the work was conducted by Virginia Tech. The excitement of the Master Gardener Volunteers regarding the use of microclover in lawns is because they see the inclusion of this nitrogen-fixing plant material in lawns as a direct complement to their efforts in urban nutrient management programs.

Efforts to incorporate compost into Virginia lawn management programs have been a priority of the Virginia Master Gardener Volunteer programs for the past 10 years.  The demonstrated success in the use of compost as either a pre-plant incorporated soil amendment to urban soils or as a topdressing addition in ¼ inch increments 1-2x per year has been extensively promoted through educational programming and other extension outreach efforts by both myself and our Compost and Biosolids Specialist, Dr. Greg Evanylo. The compost component of this research trial continues to affirm the value of compost as a soil amendment that improves both the physical and chemical properties of the soil and enhances a more sustainable turfgrass management system that requires fewer water and chemical inputs.

In summary, Virginia’s Master Gardener Volunteers are anxious to implement the research findings of the joint Maryland, Virginia, and Pennsylvania research. They believe these findings will continue and enhance their efforts in making a difference in the Chesapeake Bay “one yard at a time”.

Compost Incorporation and Microclover Overseeding in 'Yukon' Bermudagrass

Installation and maintenance of turfgrass requires a number of inputs, including fertilizer application. With the increased concern over nutrients moving into the Chesapeake Bay, especially nitrogen and phosphorus, there is interest in ways to reduce fertilizer inputs. Through a grant funded by the National Fish and Wildlife Foundation’s Chesapeake Bay Stewardship Fund, we are cooperating on a project with the University of Maryland and Penn State in a research project to do just that.

Our research

The overall objectives of the project are to evaluate and promote the adoption of compost incorporation prior to turfgrass establishment as a best management practice, to evaluate the incorporation of compost after turf establishment and to reduce nitro- gen fertilizer use by incorporating microclover at seeding or after turf establishment. Each trial includes four treatments:

• no compost/ no microclover addition

• compost addition without microclover

• microclover seeding without compost

• addition of compost and microclover

A perennial clover that closely resembles white clover, microclover fixes nitrogen, so it may be an alternative to application of nitrogen fertilizers. Within each of the treatments, half of the plot received no additional fertilizer, while the other half received 1 lb. of nitrogen per 1,000 ft2 yearly. Microclover has smaller leaves and flowers than white clover, and thus it may blend better into turfgrass stands (Photo 1).

At Virginia Tech, we evaluated compost addition and microclover seeding in ‘Yukon’ bermudagrass, while the other cooperators evaluated these treatments in tall fescue. Incorporating compost and microclover with bermudagrass seeding should improve the quality, color, quality and greenup of the bermudagrass. Com- post incorporation should improve water infiltration rates.

We established two trials at the research station in 2012, one evaluating the four treatments at seeding time of bermudagrass and the other evaluating compost addition and microclover seeding in established bermudagrass. For all plots, we have been evaluating turf cover, color and quality, as well as water infiltration.

Trial 1

This trial evaluated the aesthetic appeal of a bermudagrass plus micro- clover lawn, with compost incorporation by tilling, with and without N.

Procedures

Plots receiving compost received 2" of the material, spread evenly over the surface and then tilled in with the native soil on June 29, 2012. Plots were seeded on July 2, 2012, with either 2 lbs. ‘Yukon’ bermudagrass seed per 1,000 ft2 or 1.9 lbs. per 1,000 ft2 ‘Yukon’ bermudagrass seed plus 0.1 lb. microclover seed per 1,000 ft2.

No preemergence herbicides were applied in 2012. A March 2013 pre- emergence application of Pendulum 2G (1.5 lbs. pendimethalin per acre) and a late April application of Dimension 2EW (0.25 lbs. dithiopyr per acre) was made for crabgrass control. The preemergence crabgrass treatments were also applied in 2014.

Compost was reapplied in spring of 2014 as a 1/4" topdressing.

Results

Little to no microclover was noticed in any of the plots in 2012. Bermuda- grass establishment was greatly improved with the addition of com- post (Table 1), probably due both to the nutrients released from the compost and to a dilution of the weed seed present in the soil from the volume of compost incorporated. Without the compost, very little bermudagrass was able to establish, due to a dense stand of crabgrass and other weed species. With compost addition, fewer weeds were present, allowing for better bermudagrass establishment. With the incorporation of microclover, the use of herbicides in a bermudagrass lawn becomes very limited, and establishment can be hindered by the onset of summer annuals.

The preemergence herbicides applied in 2013 controlled crabgrass, which had hindered the 2012 grow-in of ‘Yukon’ bermudagrass. Bermuda- grass cover therefore increased from April 2013 to October 2013 in all four treatments, with the highest cover in the compost plots (Table 2). However, the reduction in summer annual weeds also allowed an increase in the natural population of white clover to increase and become more prevalent (Table 3).

As hypothesized in the research goals and objectives, incorporating compost prior to seeding increased turfgrass quality and color (Tables 4 and 5). Infiltration results also showed the benefits of incorporating compost prior to establishment (Table 6). Similar benefits of compost addition on bermudagrass color and quality were seen in 2014 (data not shown).

Trial 2

This trial evaluated methods to intro- duce microclover into existing bermudagrass turf, with compost incorporation by aeration and slicing, with and without N.

Procedures

Plots measuring 15' by 15' were arranged an eight-year-old stand of ‘Yukon’ bermudagrass. Verticutting of the plots occurred on September 5, 2012. Compost was added to plots and raked in on September 7, 2012. The plots were aerated that same afternoon. Plots receiving micro- clover were seeded on September 10, 2012. Plot maintenance in 2013 and 2014 was the same as for the previous trial.

A March 2013 preemergence application of Pendulum 2G (1.5 lbs. pendimethalin per acre) and a late April application of Dimension 2EW (0.25 lbs. dithiopyr per acre) was made for crabgrass control. Plots were mowed twice per week at 2". Half of each plot received 0.5 lb. N per 1,000 ft2 on June 13, 2013, using a 30-0-10 fertilizer containing 30% sulfur-coated urea. Plots were evaluated visually in April, May and June. Initial infiltration data were collected in July.

Results

In trial 2, we were able to establish a stand of microclover (Table 7). Since this was in an existing stand of bermudagrass, we did not have the competition from summer annual weeds that was seen in the newly seeded bermudagrass trial. Compost addition increased the amount of micro- clover compared to no compost. The percent cover of microclover did not change when evaluated in the fall of 2013 and the spring of 2014 (data not shown). Microclover increased green color compared to no microclover for most of 2013 (Table 8), but no improvement in turf color was seen in November of 2013 or April of 2014 from microclover (data not shown). Since bermudagrass goes dormant during the winter, the microclover was very evident and could be considered a weed problem, especially due to the non-uniform distribution of the microclover plants.

Compost addition increased the color ratings of the turfgrass in June 2013 (Table 9, page 28), but the effect wore off, since no benefit to turf color was seen in November of that year. When we reapplied compost later in the spring, turf color was improved (data not shown).

Conclusions

Adding compost at the time of bermudagrass seeding improved establishment. Compost addition to both newly seeded and established bermudagrass improved water infiltration rates and turf color.

Microclover, however, does not appear promising for use in bermudagrass for two reasons. Since selective herbicides are not avail- able for use in newly seeded micro- clover/newly seeded bermudagrass, weed competition will limit the stand establishment for both species. Micro- clover can be established in existing stands of bermudagrass, but a non- uniform appearance of the turf, especially when bermudagrass is dormant but microclover is still growing, may not be acceptable to turf managers or homeowners.

Comments on a Recent Visit to the Virginia Beach Microclover Demonstration Trials

Last week I had the opportunity to participate in the Virginia Tech Turfgass Field Day at the Hampton Roads Agricultural Research and Extension Center in Virginia Beach. Over the last two years project members Dr. Jeffery Derr, Dr. Mike Goatley and Turfgrass specialist Adam Nichols have been examining the establishment of a microclover bermudagrass lawn from seed, and the practice of overseeding microclover into an existing stand of bermudagrass.  In both trials they are also looking at the effect of compost addition on the presence of microclover in bermudagrass.

In the case of the establishment trial, the soil was either amended with two inches of yard waste compost or was left un-amended  prior to seeding with 2 pounds per thousand square  feet of Yukon bermudagrass, or alternatively, the same bermudagrass variety containing 5% by weight microclover . In the case of microclover overseeding trial, one-quarter inch of compost was applied as a topdressing immediately after seeding and once a year thereafter. Plots not receiving compost topdressing treatment have received urea at yearly rate of one pound of nitrogen per thousand square feet. The establishment trial was initiated in July 2012 and the microclover overseeding trial in September of 2012. The microclover seeding rate in the overseeding study was two pounds of microclover seed per thousand square feet.

Jeff has been sending me regular updates on color, quality and amount of clover present in each of the plots, however I did not grasp how stark the difference in treatments have been until seeing the two trials this past week. In brief, amending the soil with 2 inches of compost dramatically suppressed the presence of clover in the bermudagrass at this site. As can be seen in the first picture below  there is very little clover in a compost amendment plot that was seeded with the 95% bermudagrass, 5% microclover seed mixture. The amount of clover present in this plot is indistinguishable from that of a nearby compost amended plot seeded with 100% bermudagrass at the same time (lower picture).

Compost amended plot seeded with 95% bermudagrass, 5% microclover seed mixture two years ago.

Compost amended plot seeded with 100% bermudagrass two years ago.

It is likely that the enhanced availability of nutrients associated with the incorporation of compost (i.e., mostly nitrogen) favors bermudagrass growth and establishment over that of microclover.  Dr. Derr also noticed that there was much less weed competition within the compost amended plots compared to the non-amended plots during establishment. The reduced level of weed competition in these plots may have also favored bermudagrass establishment over microclover establishment. Microclover and regular old white clover are present throughout the plots that were not amended with compost. This reinforces my belief that the lack of clover cover seen in the compost amended plots is primary due to the enhanced availability of nitrogen in these plots.

What stood out to me when viewing the overseeding trail was that in plots overseeded with microclover but not topdressed with compost, the presence of the microclover resulted in a darker colored turf than in plots that were devoid of microclover. At this field station stop however Adam Nichols was quick to point out that the primary difficulty with overseeding microclover into bermudagrass is the inability in obtaining a homogenous mixture of the two species. The appearance of the plots overseeded with microclover (with or without the compost topdressing treatment) could best be described as “a patchy mosaic” of microclover within the plot. If the approach of using microclover to reduce lawn fertilizer use in bermudagrass is ever to gain favor, it appears that obtaining something close to an homogenous stand of the two species will require more than a onetime overseeding of microclover into bermudagrass.

Labeled plot in foreground was overseeded with microclover 21 months earlier while labeled plot in background was not. The annual amount of fertilizer applied to both plots is one pound of urea nitrogen per thousand square feet.

Update on Experiments from the University Park Site

Data collection is in progress for the 2013 growing season at the University Park site for Compost Amendment Study I (2 inch compost layer tilled into compacted loam soil) and Compost Amendment Study II (annual 1/4 inch compost surface application).  Ratings for spring green-up, quality, color, % ground cover, % clover cover, spring clipping yield assessments and nitrogen recovery have been collected through July, and plots are being prepared for summer clipping yield assessments and nitrogen recovery.  Microclover and tall fescue are tolerating the excessive summer heat and rains, and appear to be in excellent condition. 

Compost Study II

In Compost Amendment Study II, a ¼ layer of compost was applied to the turf surface in June.  Plots were aerated, compost was applied to the turf, and the area was sliced using a verticutting unit. A significant green-up response was noticed about 2 weeks after application.  Plots designated for the 1.0 lb nitrogen/1000 ft² application were fertilized with polymer-coated urea (Lesco Poly-Plus; 39-0-0) in June.  As with Compost Amendment Study I, a noticeable green-up from the nitrogen application occurred in late June and July.  Microclover is the dominate species in all microclover/tall fescue plots, with clover cover ratings often exceeding 90%.

The microclover herbicide tolerance experiment received early May applications of isoxaben (Gallery 75 DF), bentazon (Basagran 4.0 L), pendimethalin (Pendulum 60 WDG), prodiamine (Barricade 65 WDG), dithiopyr (Dimension 1.0 EC), and Benefin (Balan 2.5 G) to determine the tolerance of microclover to preemergence herbicides. With the exception of isoxaben, no injury to clover was detected.  All rates of isoxaben cause minor injury to clover; but injury subsided and was no longer apparent by mid-June. In June, applications of 2,4-D Amine (3.8 L), 2,4-DB Amine (1.75 L), MCPA (3.7 L) were applied to determine the tolerance of microclover to postemeergence broadleaf herbicides.  Although some minor injury was detected following 2,4-D Amine applications, the clover recovered quickly and no permanent damage occurred. No visible

injury was detected with the other herbicides.

A project website was developed and launched in July, 2013 (http://plantscience.psu.edu/reduce-runoff). The site contains information on project background, objectives, methods, and goals/outcomes.  It also provides an outreach section with information on turf fertilizer recommendations, compost selection and application methods, liming, calibration of fertilizer spreaders, and examples of how to calculate fertilizer rates.  An events calendar and other sections (pages) will be added as more information becomes available.