Title: Mulching Helps the Environment
Time Frame: 30 minutes for Preparation; 60 minutes for Action; 30 minutes for Reflection
Lesson Overview:_
Students will learn the benefits of mulching and the processes to mulch effectively. Students will
mulch identified areas of the outdoor education site in small groups, and reflect on their learning
and SSL work.
Teacher Background:
(Adapted from http://www.doityourself.com/stry/why-mulch-6-benefits-of-mulching):
Mulching is the act of placing a protective barrier (mulch) around your plants and over your bare
soil. This protective barrier can be made up of a variety of organic materials including bark or
wood chips (from various tree species), pine needles, straw, and even cocoa bean shells.
The environmental benefits include:





Weed Control: Through the use of mulch you can limit the amount of weeds that tend to
spring up in the open spaces of your garden: The mulch acts as a barrier, limiting the amount
of sunlight that can find its way to the weeds. Without sunlight, the weeds, including many
invasive plants, die.
Retain Moisture: Retaining moisture, especially during hot, dry seasons helps your plants
survive the heat, and also reduces water use.
Erosion Prevention: Mulching not only keeps existing water trapped in the soil but it also
keeps rain water from washing away your soil. It does this by breaking the fall of the water
and therefore lessening the force when the water impacts the ground.
Maintains Soil Nutrients: Not only does mulch keep soil nutrients from being washed away
with the rain, but it also can release nutrients into the soil if you are using an organic
material. This happens as the organic material slowly decomposes on top of the soil.
Encourage Earthworms to Move In: Using organic material for mulching can encourage
earthworms to occupy your garden soil. And as any good gardener will tell you, earthworms
help improve soil structure and nutrient cycling.
Although all of the environmental benefits of mulching are important, we have a particular
interest in erosion prevention because of our instructional emphasis on watershed protection.
Erosion is the process of wind, water, or other natural agents gradually wearing away soil, rock,
or land. It has several harmful effects on water quality, including:
 Excess sediment increases turbidity, which reduces sunlight and therefore lowers ability
of aquatic vegetation to photosynthesize
 Excess sediment suffocates fish eggs and benthic macroinvertebrates and clogs gills of
fish
 Excess sediment increases water temperature which decreases dissolved oxygen levels


Pesticides, metals, toxins, oil, and grease can cling to sediment and erode into the
waterway
Phosphate can wash into the water and cause algal blooms, which cause severe decreases
in dissolved oxygen
Mulching is part of the solution! Mulching slows the movement of rainwater, thereby reducing
the amount of soil that is eroded by rain. Thus, mulch decreases the amount of sediment in runoff
in local waterways.
In summary, mulching helps to support biodiversity by creating a healthier environment in which
native plants and animals can survive to reproduce.
Enduring Understanding & Essential Questions:
Enduring Understandings:
Natural resources need protection and conservation in a given environment.
Biodiversity is a natural resource.
Essential Question:
How can people help maintain and increase biodiversity in their local environment?
Next Generation Science Standards:
Science and Engineering
Practices
Engaging in Argument from
Evidence
Evaluate competing design
solutions based on jointly
developed and agreed-upon
design criteria.
Disciplinary Core Ideas
Crosscutting Concepts
Interdependent Relationships
in Ecosystems
Stability and Change
In any ecosystem, organisms and
populations with similar
requirements for food, water
oxygen, or other resources may
compete with each other for
limited resources, access to
which consequently constrains
their growth and reproduction.
Small changes in one part of a
system might cause large
changes in another part.
Biodiversity describes the variety
of species found in Earth’s
terrestrial and oceanic
ecosystems. The completeness or
integrity of an ecosystem’s
biodiversity is often used as a
measure of its health.
Performance Expectation
MS-LS2-5
Evaluate competing design solutions for maintaining biodiversity and ecosystem services.
(Clarification Statement: Example of ecosystem services could include water purification,
nutrient recycling, and prevention of soil erosion. Examples of design solution constraints could
include scientific, economic, and social considerations.)
Maryland Environmental Literacy Standards
STANDARD 1 ENVIRONMENTAL ISSUES
The student will investigate and analyze environmental issues ranging from local to global perspectives and develop
and implement a local action project that protects, sustains, or enhances the natural environment.
Topic A: Environmental Issue Investigation
Topic B. Action Component
Indicator 1: Use recommendation(s) to develop and implement an environmental action plan.
Indicator 2: Communicate, evaluate and justify personal views on environmental issue and alternate ways
to address them.
Indicator 3: Analyze the effectiveness of the action plan in terms of achieving the desired outcomes.
STANDARD 4 POPULATIONS, COMMUNITIES AND ECOSYSTEMS
The student will use physical, chemical, biological, and ecological concepts to analyze and explain the
interdependence of humans and organisms in populations, communities and ecosystems.
Topic B: Population Dynamics
Indicator 1: Analyze the growth or decline of populations and identify a variety of responsible factors.
Topic C: Community and Ecosystem Dynamics
Indicator 1: Explain how the interrelationships and interdependencies of organisms and populations
contribute to the dynamics of communities and ecosystems.
5E Lesson
Engage: (Preparation)
What is erosion? How can erosion affect water quality?
Explain:
Ask students: why do people mulch? (open ended)
Show OEEP SSL Power Point.
Review the benefits of mulching with students. (See Teacher
Background)
Reminder: Explain and show what poison ivy looks like.
Preparation Notes
for the Teacher:
Before you come to OE:
1. Meet with your
coordinator ahead of
time to become
familiar both with the
areas that need
mulch, and the areas
that the piles of
mulch are located.
2. Introduce SSL using
the SSL power point,
and introduce this
mulching project to
your students using
the OEEP SSL Power
Point. (Explain)
3. Provide safety
guidelines to students
about poison ivy:
 Wear long sleeves
and long pants
 Remember “leaves of
three, let it be" is a
good rule of thumb
 Leave hairy vines
alone, too!
 Poison ivy is active in
winter – avoid hairy
vines
Explore: (Action)
1. Divide the students into groups of no more than 5 and assign
each group a specific area to mulch. Each group should have one
cart, and one tool per student (about half should have rakes to
spread the mulch, and half should have pitchforks or shovels to
pile mulch into cart).
2. Congregate at the pile of mulch closest to your desired mulching
area. Review safety information and demonstrate proper tool use.
3. Take the students with rakes to the mulching area. They can start
weeding and preparing the area while waiting for the mulch to
arrive.
4. When the mulch arrives the students can dump it into a pile in
the center of the area and the students with gloves or rakes can
spread it.
 Spread the mulch about 3-4 inches thick. The more mulch the
better!
 Mulch one smaller area completely with no holes, bare spots, or
gaps, before moving on to another area.
At Outdoor Ed:
 If mulching in a garden, weed and rake the area first.
 If mulching around trees be sure to create a donut shape around Gather equipment at the
Smith Center:
the tree – not a volcano – and don’t go too high up the tree.
1.
2.
3.
Carts for
transporting the
mulch: located
near greenhouse
Shovels and
pitchforks for
moving mulch
from pile to cart:
located in locked
cage next to
greenhouse
Rakes for
spreading mulch
on location:
located in locked
cage next to
4.
5. Return equipment at the end of the session! Account for all
equipment and return to the proper location.
Evaluate: (Reflection)
Prepare students for their writing by asking them to talk with an
elbow partner about:
 What did you learn about mulching that you did not
know before?
 How did this SSL work help the environment? (i.e. what
need did your service address)
 Who or what benefitted?
Have students write their answers to the following SSL form
questions in their notebooks:
1. What did you do?
2. What need did your service address?
3. Who benefitted from your service?
4. What did you learn about yourself?
5. How was this experience connected to something you learned in
a class at school? (For example, English, Mathematics, Science,
Social Studies, Arts, Physical Education, Health, Foreign
Language, etc.)
greenhouse
Gloves if
students are
spreading mulch
with their hands
Determine how you will
group students and which
adults will be responsible
for each group.