soil-v-water - Knowledgebase Question

Detroit, MI (Zone 5B)
Question by yvonnemccask
April 18, 2007
i am helping my granddaughter with a school project and the question is

Answer from NGA
April 18, 2007


Three cheers for you! Helping your grandchild with a science fair project will be rewarding for everyone involved! Here's some background information to get you started:

Have you ever wondered if plants grow better in water or soil? Well in this experiment you will learn all about the plants, and what kind of habitat that they adapt to ( water or soil).

Water is one of the most important things to all living things, especially plants, because plants don't eat food like animals. Water is made out of two atoms of hydrogen and one atom of oxygen, when those three atoms combine you get a water molecule. That may not be much, but mix lots and you can get a glass full of water, and you can water lots of plants with one glass of water. Every living thing on earth needs water to survive, and they get water from many sources. You can get water from the ocean, lakes, streams, snow, glaciers, rain, hail, and more.

Soil is one of the most important things to plants. Soil is made up of broken down rocks and minerals, eventually in about a century the soil will form. You just have to have the right climate, good land surface features, and a lot of time. The soil provides plants with special nutrients that help the plants grow faster and bigger. The soil also helps the plants grow in another way, it covers the roots. You may plant the seeds in the dirt, but then the stem grows up and out of the soil. But the plant would die if the roots were not covered. Plants "eat" through their roots, so soil is one of the most important things to grow a plant.

Hydroponics is the artificial way to grow plants. It was developed in the 1860?s by the man named Julius Von Sachs. The theory of hydroponics became a scientific fact once other scientists proved it could be done. Hydroponics was a very good idea, but you had to put sand like grains in the bottom of the pot, so it can work like the soil, and help the roots. In the 1930?s people started to grow large crops hydroponicaly. Now the scientific method of hydroponics is used all around in experiments, and in crops.

Plants are grown all around the world, for food and decoration. This experiment involves radishes, green beans, grass, bachelors? buttons, and snapdragons. Green beans and radishes represent food plants and herb plants, the snapdragons and bachelors buttons are examples of flowers, and the grass is a common land covering. Plants are an important part of the food chain, and humans couldn?t live if they didn?t have plants. Some people don?t have good soil, so they could grow plants in water. Using these plants won't show if all plants grow in water, but will tell about the majority of plants.

You'll need 10 styrofoam cups, seeds, sand and potting soil


1. First gather all materials to begin experiment
2. Then place soil in 5 cups about 4-inches high with potting soil
3. Place white purified sand in 5 different cups about 4-inches high
4. next place 5 radish seeds in one of the soil cups and 5 seeds in one of the sand cups, label them "radishes"
5. place 5 cucumber seeds in another cup filled with soil and 5 seeds in one of the sand-filled cups and label those two cups "cucumbers"
6. place 5 snapdragon seeds in one of the soil filled cups and 5 seeds in one of the soil-filled cups and label them "snapdragons"
7. place 50 grass seeds in one of the sand-filled cups and 5 seeds in one of the soil-filled cups label both of them "grass"
8. place 5 bachelor?s buttons in the last soil-filled cup and 5 more seeds in the last sand cup label them "bachelor's buttons"
9. after that carefully pour 200ml of water in the sand-filled cups trying not to stir up the seeds and sand
10. water the soil-filled cups when the top of the soil looks dry
11. make sure that the sand-filled cups have water all the time; you could make holes in the bottoms of the cups and set the cups in a try of water, just to make sure the sand stays wet
12. record the plant growth for 5 weeks and record the data
13. on the 35th day pull the plants and get all the dirt off so you can weigh and measure the plants

Best wishes with your project!

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