Managing Yard Waste

In 1994, a law banned grass clippings,
tree leaves, branches and twigs from all
landfills in Michigan. These items are
considered yard waste, and prior to 1994, it accounted
for approximately 20 to 25 percent of Michigan’s throwaway
trash. A few municipalities and private businesses
have developed composting centers to process this
material. This has provided a disposal mechanism for
some Michigan residents. For those who would like to
handle yard waste on their own property, the techniques
listed below can transform grass clippings and
tree leaves into resources for lawns and gardens.

Recycling Grass Clippings

When you mow, return the grass clippings to the turf
whenever possible. Mulching mowers are specifically
designed to accommodate this procedure, but any
mower can return clippings to the lawn. Grass clippings
begin to break down quickly after mowing, releasing the
water and nutrients contained in the tissue. The nutrients
(particularly nitrogen) can be returned to the soil
and used by the lawn. Recycling nutrients will reduce
the total amount of nitrogen fertilizer needed by the turf
each growing season.

Returning clippings to the lawn will not harm the grass
plants or contribute to thatch buildup. Thatch is the
accumulation of dead and decomposing turf stems,
leaves and roots intermixed with live plant roots and
soil that occurs at the soil surface. It can be viewed by
cutting downward into the lawn, peeling the sod back
and examining the cut piece from the side. A thatch
layer of approximately 1/2 inch is beneficial because it
acts as a buffer at the soil surface and protects the
plants from extreme weather. Thatch that builds up
over 1 inch, however, can inhibit water and air movement
and weakens the turf stand. If you have a thatch
layer of 1 inch or more, you may want to consider a
core cultivation of your lawn to alleviate the thatch
problem.

Excessive grass clippings left in piles on the lawn surface
will smother and severely injure the turf. Simply
spread them out over a larger area using a rake or the
mower, use them as mulch in gardens or landscape
beds, or put them in your compost pile. If excessive
clippings are a routine problem on your lawn, try mowing
more frequently and raise the mowing height.
Mowing heights of 2.5 to 3.5 inches are recommended
for most lawns.

Grass Clippings as Mulch

Grass clippings can effectively be used as mulch for
gardens or landscape beds. Be careful when placing
the clippings around tender young plants — the clippings
can heat up as they decompose, and this may
injure young transplants. Also, refrain from using clippings
for mulch that were recently treated with weed
control products (herbicides). MSU research indicates
that the herbicide can volatilize from clippings and
injure sensitive plants such as tomatoes, beans and
annual flowers. Allow at least two weeks after application
of weed control products before using treated clippings
as mulch.

Grass Clippings as Compost

Grass clippings make an outstanding contribution to
compost piles because of their high nutrient content.
Efficient composting is accomplished by layering green
material such as grass clippings, weeds or kitchen
scraps with brown materials such as leaves and soil.
The compost is a valuable resource for landscape and
garden beds as a soil amendment or mulch.

Tree Leaves

Raking, hauling, bagging and disposing of tree leaves
has been an annual event for homeowners and turf
managers for many years. MSU researchers have
found that mowing these leaves back into the turf is an
appropriate alternative. In these studies, more than 6
inches of tree leaves have been mulched into lawn turf.
Several types of leaves have been used, such as oak
and maple, with no adverse effects on lawn turf.
Reports from professional turf managers who have
been practicing this technique on golf courses and
commercial turf have been positive. Homeowners interested
in an alternative to raking leaves might want to
try mowing them. A couple of passes with the mower
breaks the leaves down into small pieces. The leaf
residue will be evident after mowing, but it will sift into
the turf within a few weeks and will be unnoticeable in
the spring. You can even rake leaves that accumulate
in planting beds, fence lines or other areas out into the
lawn and mow them. For best results, use a mulching
mower, raise your mowing height to better accommodate
the tree leaves and mow when the leaves are dry.

Fertilizing Home Lawns

The first step in developing a fertilizer program
for your lawn is to identify the
objectives for the lawn area on your
property. Homeowners demand a wide range of functions
from their lawns. Many property owners desire a formal
appearance with the lawn providing a uniform and manicured
setting. Others may utilize their lawns as highly trafficked play
areas, while others are interested in as little maintenance as
possible to provide a reliable and stable surface. Carefully
consider the function for your lawn along with the growing
conditions on your property, and then set realistic objectives
for your lawn. The fertilizer programs described below are
structured into three levels of maintenance-low, medium and
high. Choose the level of maintenance that will best fit the
level of input you want to dedicate to your lawn area and also
achieve your objectives.

All property owners should understand the environmental
considerations of their lawn maintenance activities. Fertilizers
can be used in a manner that will minimize the potential for
off-site movement. Properly fertilized turfgrasses can provide
an excellent filter for environmental contaminants, but excessive,
poorly timed or misapplied fertilizers have the potential
for off-site movement resulting in degraded water resources.
Of particular concern are fertilizer particles that land on
impervious surfaces such as driveways and sidewalks. These
materials are likely to run off in rainwater and be carried
downstream. Be aggressive in sweeping these particles back
into the lawn area where they will be utilized. Homes located
in urban areas with curb and gutter systems that are connected
to storm water drainage systems should consider themselves
connected to surface water resources via the storm
water handling system. Sensitive sites such as waterfront
properties should refer to Turf Tips E11TURF, “Maintaining
Waterfront Turf” for special instructions.

The three main components of turf fertilizers are nitrogen (N),
phosphorus (P) and potassium (K) (potash). A fertilizer
labeled 20-5-15 contains 20 percent nitrogen, 5 percent phosphorus
and 15 percent potash by weight. The importance of
each of these components is discussed individually below.

Soil Testing

Knowing the conditions of your soil is one of the
most important factors in growing a healthy lawn. Your MSU
Extension office can instruct you on how to conduct a soil test
through the MSU Plant and Soil Nutrient Laboratory.

Components of a Fertility Program

Nitrogen

Nitrogen is an essential nutrient for all plant growth and is
available in many forms from garden centers or professional
lawn care services. To successfully meet the objectives of
most lawn areas, annual applications of nitrogen are required.
The total amount of nitrogen required each season will vary,
depending on the desired level of maintenance and the growing
conditions on your property. Recommendations for the
amount of nitrogen and time of application for each maintenance
level (low, medium, high) are listed below in the timing
chart.

High maintenance situations are those where a high quality,
uniform, dense lawn or athletic field is desired and an irrigation
system is available. The primary turf grass species used in
this situation is Kentucky bluegrass. The medium maintenance
situation is for most general lawn or athletic field areas
where no supplemental irrigation will be applied, but the intention
is to optimize turf growth for quality, density or playing
conditions. The low maintenance situation is intended for lawn
areas where the lowest level of input to maintain turfgrasses
for a stable surface is desired.

Please consider the environmental responsibility of applying
nitrogen to your lawn. Nitrogen is easily dissolved in water.
When too much nitrogen is available for turfgrass plants to
consume and excessive water is present, nitrogen can move
away from the lawn and into water resources. This situation
can be easily avoided by following these suggestions.

-Do not apply more than 1 pound of nitrogen to 1,000
square feet of lawn per application.

In general, the recommendations located on lawn fertilizer
bags are designed to apply the desired amount — 1 pound of
nitrogen per 1,000 square feet of lawn. For example, if a bag
of fertilizer lists that it will cover 5,000 square feet of lawn, it
will deliver approximately 5 pounds of nitrogen to that area.
Follow the bag directions and don’t overapply.

-Consider using slow-release forms of nitrogen.

Slow-release nitrogen fertilizers are designed to release nitrogen
to the plants over a long period of time. Slow-release fertilizers
include organic sources such as poultry manure or
sewage sludge. Others include common nitrogen sources
such as urea or ammonia nitrate that are coated with materials
that release the nitrogen slowly over time. The portion of
slow-release nitrogen available in the fertilizer product is listed
as “water insoluble” nitrogen on the label.
Choose products with slow-release nitrogen to reduce the
potential for off-site movement.

-Keep fertilizers off impervious surfaces. Sweep fertilizer

particles from driveways and sidewalks back onto the lawn
area. This will prevent them from moving downstream with
rain water.

Phorosphorus

Phosphorus is a common component in most turfgrass fertilizers.
It is an important element for turf growth and is critical
for establishment of new seedlings. Phosphorus levels in soil
are stable, and most Michigan soils have adequate phosphorus
levels and therefore may not need continual applications
of phosphorus. A soil test will reveal the amount needed
annually on your lawn. Phosphorus is a primary water quality
concern in Michigan. Phosphorus applied to lawns is quickly
bound to soil particles after the fertilizer has been adequately
watered into the lawn. It is important to sweep these fertilizer
particles from impervious surfaces to reduce the potential for
them to move away from lawn areas. Sensitive lawn sites
adjacent to lakes, streams and ponds should use no-phosphorus
fertilizers when soil levels for lawns are adequate.

Potassium

Potassium is also a primary turfgrass fertilizer element. It is
usually applied in quantities ranging from 50 to 100 percent
of the nitrogen rate at each application. Potassium levels in soil are relatively stable. A soil test will reveal the amount
needed annually on your lawn. Levels below 120 pounds of K
per acre are low for lawn turf; soils with levels above 250
pounds of K per acre need no additional potassium.
Potassium is not regarded as a major water quality concern.

Putting Your Program Together

Identify the objectives for your lawn and choose the nitrogen
fertility program from the chart below that will best fit your
objectives. Phosphorus and potassium should be added to
the program on the basis of soil test information.
Once you have picked the level of maintenance and quality
for your lawn, you can target the application time for the most
effective use of the nutrients. The application times listed in
the table take advantage of late fall fertility. Research at
Michigan State University has demonstrated several benefits
for late fall nitrogen applications. During this time of year, the
top growth of the plant slows down as the temperatures cool,
but root growth continues to be active. Fertilizing at this time
of year will enhance the root growth and enable the plant to
store additional carbohydrates. These reserves provide vigorous
spring green-up, allowing the traditional early spring fertilizer
applications to be delayed. This adjustment helps limit
the heavy top growth usually associated with early spring fertilizer
applications. Environmental studies at MSU reveal that
this late fall application does not pose an elevated risk to
water quality. The application times listed in the table are
general guidelines for the mid-Michigan area. Adjustments
can be made for growing conditions in northern or southern
areas.

Special Considerations

You will need to adjust fertility for grasses grown in shady
areas by reducing the overall nitrogen applied. The overall
nitrogen applied can also be reduced by approximately 1
pound of N per 1,000 square feet when you return clippings
to the turf.

Home Lawn Fertilization Timing Chart

Pounds of nitrogen per thousand square feet of lawn