Authentic Lessons for 21st Century Learning

How Does Your Garden Grow?

Chemistry & Soil Health

K20 Center, Quentin Biddy, Dr. Jean Cate, Dan Hounslow | Published: July 20th, 2022 by K20 Center

  • Grade Level Grade Level 9th, 10th, 11th, 12th
  • Subject Subject Science
  • Course Course Environmental Science
  • Time Frame Time Frame 4-5 class period(s)
  • Duration More 300 minutes


Students will explore soil chemistry, vegetable growth needs, environmental impact, and soil health through project based learning by creating a school garden proposal.  Acknowledgement: Funding provided by USDA to Project No. 2012-02355 through the National Institute for Food and Agriculture's Agriculture and Food Research Initiative, Regional Approaches for Adaptation to and Mitigation of Climate Variability and Change.

Essential Question(s)

Overarching: How do soil health and farming practices connect to environmental impact? Topical: How do farming practices impact soil health?



Students will view pictures of crops growing in unhealthy soil and answer the question, "What's wrong with this picture?" Students will then discuss their connection to agriculture and how this connection has its foundation in soil health. Students will view USDA Video: Healthy Soil, Healthy Farmers.


Students will use a USDA School Garden Checklist as a guide to conduct group research about preparing a school garden project proposal. This proposal will be presented to the class and administration


Students will create and present a garden proposal that includes ways to improve vegetable production through recommended farming practices based on soil test results. Students will provide peer feedback on their presentations.


Students will test soil samples from possible garden sites and compare them to soil samples from other sites. Students will analyze each sample for common soil chemistry tests, which indicate soil with healthy balances of nutrients such as Nitrogen, Phosphorus, and Potassium.


Students will produce group School Garden Proposals to be presented to the administration and/or local community members and use a rubric to evaluate their project. As an option students may submit their proposals to a School Garden Proposal Review Committee consisting of community member or the local County Extension office.


  • Soil test kits (These may be purchased at any big box hardware store)

  • Internet connected devices (at least one per group of three)

  • Stirring rods or sticks

  • Paper towels

  • Plastic cups

  • Water source: approximately two gallons of DISTILLED water needed for soil tests

  • Soil Samples: Four soil samples from different locations

  • Simple vegetable seeds, such as peas – several per group


Show the students a series of pictures of poor soil health conditions (e.g. yard with yellow patches, compacted soil, poor drainage, erosion, etc.).

Ask them: What's wrong with this picture? What do you think is the cause? You may lead a discussion or use a strategy such as Commit and Toss.

Next, ask the students the question: Does what we eat have an effect on the environment? How? What evidence do you have or how do you know this?

Facilitate a student discussion to elicit student prior knowledge regarding agriculture and farming and how they relate to the environment. Once students have a general understanding of where their food comes from and that the beginning of most food production depends on soil to grow the food we eat or to feed the livestock that we eventually eat.

Then ask the question: What is soil?

Student responses will vary; however the instructor should help guide students to understand the 4 components of soil and any other characteristics of soil.

Show the USDA Video: Healthy Soil, Healthy Farmers the Natural Resources Conservation Service (NRCS) Building Soil Health

Lead a discussion or ask students to think, pair, share about what the term "soil health" means, being sure they answer the following questions:

  • What criteria factor into soil health?

  • What are the benefits of having healthy soil?

  • What soil management practices or strategies would improve soil health?


Inform students that they will be planning a school garden and that one component of planning a garden is assessing the health of the soil.

Divide the class into collaborative working groups of 5 or 6. Assign each student a role corresponding to the six components (i.e. evaluate your available space, find resources and make partnerships, soil health, design challenge, plant palette, build and use your garden) found on the USDA School Garden Checklist ( Explain that each student will be responsible for leading the group in their assigned aspect of the garden-planning project.

Pose the question to the groups: if we are going to plan a garden, what things might we need to consider? Have the students discuss with an elbow partner to create a list. Give the students enough time to discuss this thoroughly. Have the students share out with the class and compile a class list on the board.

Pass out a copy of the Student Information: The USDA School Garden Checklist, Garden Planning handout, and the School Garden Presentation Rubric to each student.

Go over the USDA School Garden Checklist pointing out what each role in the garden planning will entail. Go over the Garden Planning handout directions along with the presentation rubric with the class so they understand the project and your expectations.

Explain to the groups the time they will have to plan their school garden. Since this is a group project, allow some class time and Internet access to research and plan. (Additional resources can be located at


Have groups present a rough draft of their plans. As each group presents, ask the others to make one suggestion for improvement and ask one question for peer feedback. This feedback will be used to refine their final presentations.

After students have given peer feedback, provide students with a brief overview of nutrient cycles (,,, related to agriculture. Have students incorporate this information into their presentations.


Have students collect soil samples from possible garden sites around campus.

Have students analyze each soil sample, making sure to record the data for the most common soil chemistry tests: soil pH, Nitrogen level, Phosphorus level, and Potassium level.

Preparing the Soil Samples:

  1. All of tests require a soil solution which is best to prepare at least a day before to get better results due to the nutrients leaching into the water.

  2. Have the students create a soil solution by adding 100 mL of soil and 200 mL of water to a beaker or other container.

  3. Now have the students use the stirring rod or sticks to blend the mixture.

  4. Ensure that students clean the stirring rod thoroughly or use a different stirring utensil for each soil sample.

Testing the Soil Samples:

  1. Now that the students have a garden plan have them test the soil types to determine the level of the nutrients present and if any soil modification will need to be done based on the chosen crops and their nutrient requirements. Hand out the Student Information: Soil Testing & Presentation handout.

  2. Provide each group with a soil test data sheet OR have each group create their own data table (See Sample Soil Test Table below).

  3. Based on the specific directions for the soil test kit you have purchased, review the procedure for soil testing with your students.

  4. Have students document their process and results using tablets or their phone's camera if it is a "Bring Your Own Device" (BYOD) approved environment. These pictures can be incorporated into their final presentation.

Sample Soil Test Data Table

Optional Extensions:

Test Your Results:

  • Guide students to grow their own vegetables in the sample soils and predict the results using their soil test data as evidence.

  • Choosing one simple vegetable type like peas, have each group grow one plant in each of the soil sample types.

  • Have students plant in individual plastic cups that have holes punched in the bottom for water drainage.

  • Have the students come up with the planting, watering, and sunlight schedule based on the recommendations that come on the seed packet.

  • Also have the students come up with a plan for evaluation. How are they going to determine which soil is the best?

  • Have each group write up and submit for your approval their group's watering schedule, light, plan of evaluation and predication.


Option 1. Present your plan to the administration

Now that your students have presented their proposals they can create a singular proposal based on the information they researched and presented.

Have them prepare the proposal for a formal presentation to the school administration to receive feedback and possible approval to pursue and implement the school garden project.

This extension will only be successful if you have a designated committee that is passionate about the project.

The first step is to create a class committee, that is, a group of students that spearheads the collaboration as well as the members of the group who presents the proposal to the administration. Have student volunteer for committee member positions which can include a leader (and possibly co-leader), and then specialists in research, community outreach, and presentation production and design. You and the committee members must be willing to meet outside of class-time, either before or after school. During your meetings, facilitate the process of the proposal creation as well as outreach to the administration and the community. In addition to the information already researched, include additional research over other successful school garden projects. You can start with:

Option 2. Written proposal

Have students prepare and turn in their school garden proposal. Have various community members and/or your local county extension office serve as a School Garden Proposal Review Committee to "review" each proposal.

After the committee has reviewed each proposal return the proposals to the students to allow them to read the feedback provided by the committee. You can utilize the committee scores as one part of the project grade.