Activity for Module VI, Urban Agriculture

Activity for Section C: Urban Agriculture in the Agroecosystem

• Activity 1: Plant Associations and Interactions

Activity 1: Plant Associations and Interactions

Purpose: Students will begin to think about how the associations and interactions of plants affect nutrient flows, water conservation, and pest control in a mixed vegetable garden or small urban farm.

Advance preparation: Become familiar with the questions below (also provided in this separate MS document). Print the answer table and cut it into individual slips of paper. Pass out the answer slips to students. Web access will be helpful since this exercise involves plants, plant pests, and terms that students may be unfamiliar with.

Estimated time: 50 minutes

1. Ask your students to help you plan a garden or small urban vegetable farm that will have different types of vegetables growing close together. In this exercise, they are going to learn about some of the beneficial ways plants interact and how they affect nutrient flows, water conservation and pest control. Emphasize that there is a lot that scientists still don’t know that they continue to research.
2. Read the questions provided. If there is more than one answer slip for a question, it is indicated after the question.
3. Suggested discussion questions are included.

Important note for this exercise: Companion planting is widely accepted in home gardens. Some companion planting has been scientifically verified, some has not. There are a number of claims in books, blogs, and other websites that have not been verified in scientific studies. Maintain a critical attitude regarding what you read about companion planting. Of course, if you use a practice in your garden that works, continue to use it. See this article, Is Companion Planting Scientific?, for more. The examples provided in this activity have been successful in scientific trials.

Questions:

1. An area of my garden has compacted soils. What can I grow in the fall to help loosen up the soil for the following growing season? (One answer slip)
   • Discussion:
     • Why might turnips help loosen compacted soil?
     • What are some growing challenges associated with compacted soil?
2. I’ve had lots of weed problems with purslane and lambs quarters in the past. What can I sow to suppress weeds? Why? (One answer slip)
   • Discussion:
     • What is allelopathy?
     • What are some other benefits of using cover crops?
3. I want to plant a crop that has deep roots after growing lettuce, which has shallow roots. What vegetable I could choose?  (Two answer slips)
   • Discussion:
     • Why might it be a good idea to plant a deep-rooted crop after growing a shallow-rooted crop?
     • I have shrubs and trees in and near my garden. What should I do with the fallen leaves in autumn? Hint: shrubs and trees typically have deeper roots than annual crop plants.
4. What is a plant I can grow that would supply nitrogen? (Two answer slips)
   • Discussion:
     • What is nitrogen fixation?
     • Create a planting plan that will reduce the amount of fertilizer I will need to apply to my lettuce.
5. Discussion only: The Three Sisters of indigenous American agriculture are corn, beans, and squash. Based on what you have learned so far, why do you think indigenous Americans planted these three species together?
6. I plan on growing squash and zucchini, but I’m concerned about squash bugs and squash vine borers. What can I plant that will act as a trap crop for these pests? (One answer slip)
   • Discussion:
     • What is a trap crop?
     • What is another example of a trap crop?
7. Last year, I had problems with thrips on my tomato plants. What can I interplant with my tomatoes this year that will mask the tomato’s scent and deter the aphids? (One answer slip)
   • Discussion:
     • What is a repellent crop?
     • What is another example of a repellent crop?
8. I want to plant eggplant, but I’m concerned about damage from the Colorado potato beetle. What can I plant adjacent to eggplants that will attract beneficial predatory insects to reduce beetle populations? (One answer slip)
   • Discussion:
     • What is another example of plants that attract beneficial predatory insects to the garden?
9. I have apple trees that bloom each spring, but I get less fruit set than I want. What can I plant around my apple trees to increase fruit set? (Two answer slips)
   • Discussion:
     • What is another possible benefit of planting trap crops, repellent crops, plants that attract beneficial predatory insects, or pollinator strips?

Answer slip and discussion key