Farms as Ecosystems

An ecosystem – a group of living things interacting with their environment - gives us many benefits when healthy. We scientists say that an ecosystem is healthy when it can support high biodiversity- defined by having many different types of living things in numbers that are in proportion to their level on the food chain. We call the benefits of healthy ecosystems ecosystem services. You can probably list several things the environment gives us off the top of your head. They include food, clean water, fresh air, holding soils in place, aesthetics, mood lifting scenery, tourism, recreation, disaster prevention, and much more.

A farm is also an ecosystem! Food systems are highly modified by people but by definition are a group of living things growing together and interacting with one another. Besides plant crops and farm animals, a farm has insects, birds, microorganisms, and interacts with any other nearby wildlife like deer, mice, or raccoons. There are farming techniques that both decrease and increase biodiversity in these systems. In the experiment below, you can model at home what happens when we use different techniques to grow food.

Biodiversity in Agriculture Experiment

There are several variables affecting biodiversity you can test at home. Despite what you choose, the basic supplies include seeds, a couple pots (they do not need to be big), soil, and a light source like a window or lamp. Optional: a tray to catch water. For each experiment, make a prediction about what will happen and give a reason for your thinking. Record the plants as they grow either in pictures or in writing.

Monoculture vs. Polyculture
In one pot, plant at least 3 seeds of the same type of plant. In the other pot, plant seeds of the plant in the first pot, but also seeds of 2 other types of plants. The first pot is a monoculture, the growing of one type of plant in a system. The second is a polyculture, when different types of plants are grow at the same time in the same system.

Fungicide application
Fungicides are substances that kill fungi, which can be found in the soil and air. Some fungi help plants and others harm them. Farmers often spray copper-based fungicides to prevent fungal infections of crops. To set up, prepare two pots with soil and plant your seeds. Take care of this pot as you normally would. For the second pot, prepare a fungicide solution by dissolving 1 tablespoon of baking soda in a gallon of water. Once a week, or as often as you decide, water the second pot with the fungicide.

Chemical vs. Organic fertilizer
Fertilizer is a substance that gives additional nutrients to plants so that they can grow more than they might otherwise. We have multiple ways of preparing fertilizer. One popular choice is nitrogen-based salt fertilizer, known as chemical fertilizer. Another popular fertilizer is compost, known as organic fertilizer, because it is made from decomposed plants and animal products.

For this experiment, prepare 3 pots with soil and seeds. The first will be the control, so nothing extra will be added to it. For the second pot, prepare a solution of nitrogen fertilizer (found in garden stores as a salt that can be dissolved in water) and apply it according to the directions that come with the fertilizer. For the third pot, mix compost or peat moss into the potting soil (one-part compost to two parts soil) and then plant seeds and care for as normal.

Reflection

After you have done these experiments, consider the questions below.

• What was the result of your experiment?
• Did the manipulated conditions grow larger or healthier plants?
• Did your manipulated variable increase or decrease biodiversity in your system?
• Why do you think you saw the trends you did?
• What does this mean for a larger farming system?
• Did your experiment support the idea that higher biodiversity is good? Why or why not?
• Does this leave you with any questions?