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.
