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CPU sets up Hydroponic System!

Did you know during World War II, locally established hydroponic systems were used to grow fruits and vegetables to feed US Armed Forces stationed on non-arable islands in the Pacific? Hydroponic systems have been around for a long time and play an important role in the agriculture industry. Students at Center Point-Urbana High School set up their own system to explore how a lettuce will grow in nutrient-rich water. The system was designed by Phil Pfister, Linn County Master Gardener and provided by Linn County Farm Bureau.

We began our lesson by watching TrueFoodTV's "How does it Grow? Spinach" video. This video was a great introduction to how hydropinic systems work. Our classroom system is set up with a water reservoir, plant tray, growing medium (clay pebbles), water pump, tubing and plumbing fittings, timer and grow light.

Plants need air, light, water and nutrients to grow. Plants do not need soil as long as we provide all of the necessary nutrients. Nutirents are essential to plant success. Our macronutrients include Nitrogen, Phosphorous and Potassium.

Nitrogen gives the plants a rich green color and increase protein levels. Phosphorous stimulates root formation, stem growth and flowering. Potassium encourages increased growth and disease resistance.

Hydroponics have many pros and cons!

Pros: According to the National Ag in the Classroom lesson, "70% of fresh water globally is used for agriculture. By 2050, increase population may require as much as 15% more water to feed everyone!" Hydroponics uses up to 80% less water than conventional farming and can be recycled. Hydroponics also allows for greater control over temperature, pests, lighting, humidity, water, etc. Hydroponics crops can be grown in the middle of cities or out in the county. It can also increase local food production.

Cons: Many hydroponic systems rely on artificial light and electricity. Most hydroponic systems only grow leafy greens, even though it is possible to grow other crops, it might not be as efficient or realistic. There is no buffer between the nutrients and the plant roots. Adding nutrients is a delicate balance. Too much and it can burn the roots and not enough can cause yellowing and delayed growth.

Students also began an experiment using the National Agriculture in the Classroom test-tube hydroponic kit. Half of the class will grow soybeans in distilled water and the other half will grow their seeds in nutrient-rich water. We used FloraGro, a general hydroponic solution. Step one, place the soybean seeds in the rockwool cube; step 2, transfer seedlings to test-tubes once germination occurs; step 3, observe and record findings.

According to our Linn County Farm Bureau Education Outreach Friday Field Reports, "The soybean is a species of legume native to East Asia, widely grown for it's bean. Soybeans are grown for livestock feed, bio-diesel, vegetable oil, industrial applications, tofu, soymilk, soy sauce, fresh edamame and more! Nearly 42,000 Iowa farmers grow soybeans! The average soybean farmer in Iowa grows enough grain each year to nourish 60,000 people."

Discussion time! We asked the following questions...

1. What will happen if you take a nutrient away?

2. How does humidity play a role?

3. How many mediums are there to grow the plant in?

4. Does the plant grow normal size? Will it take the same amount of days to mature?

5. Will the plant absorb the same amount of nutrients?

6. Can you think of more pros and cons?

Interested in incorporating hydroponics into your own classroom? Visit to learn more or contact!

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