After a long, hot, dry summer, southern Arizona farmers are seeing green again. KOLD News 13 reported on November 11 that "historic" October and November rain has revived crops at Caywood Farms. Alfalfa fields that sat fallow since July, so dry the ground was "crunchy when you walked on it," are now green and nearly ready to cut. Coolidge Dam's storage rose from about 100 acre-feet to roughly 170,000 acre-feet, and water is expected to reach the farm's canals from the Gila River in a few weeks for the first time since March.
The same storms brought a challenge too: rain soaked the cotton waiting to be harvested, which can lower its grade. Water, it turns out, is a big deal no matter which way it goes.
So here is a question for your young scientists: when rain finally falls, why does some ground drink it in while other ground lets it run right off or drain away? The answer is soil, and your kids can test it this week.
What your kids will learn
Grades K-5
- How sand, garden dirt and potting soil look and feel different
- Why some soils soak up water like a sponge and others let it rush through
- What makes a test "fair": changing only one thing at a time
- Recording results with drawings, simple charts and a ruler
Grades 6-12
- Soil structure, particle size, pore space and aeration
- Water retention and drainage, and why farmers in a desert care about both
- Independent, dependent and controlled variables
- Measuring germination speed, plant height and root growth, then graphing results and drawing evidence-based conclusions
This week's activity: the Soil Sponge Test
All you need are three plastic cups, three jars or glasses, and three soils: some sand, some dirt from your yard and some potting soil. Arizona yards are a great place to find interesting dirt, from sandy wash soil to hard caliche-crusted ground.
- Make drainage holes. With an adult's help (and a pushpin or small nail), poke five small holes in the bottom of each cup.
- Fill and label. Fill each cup halfway with one soil. Label them Sand, Yard and Potting.
- Predict. Ask each child which soil will hold the most water and which will drain fastest. Write the guesses down.
- Pour the "storm." Set each cup on top of a jar. Pour the same amount of water (half a cup works well) into each one at the same time.
- Time and measure. Use a timer to see how long each cup drips. After five minutes, measure how much water collected in each jar with a ruler or measuring cup.
- Figure it out. Less water in the jar means more water stayed in the soil. Which soil would you want around your plants after a desert rain?
- Take it further. Plant two of the same seed in each cup and watch which soil grows the healthiest seedling over the next two weeks.
Make it a full soil science unit
The Soil Science Experiment Kit (4 Pots) turns this into a complete, side-by-side experiment. It includes four 3-inch peat pots, traditional potting mix, expandable coconut coir pellets and two seed varieties picked for fast germination, plus digital curriculum and worksheets for your grade band, emailed after purchase. Kids plant the same seeds in different growing media, and different seeds in the same medium, then track germination speed, growth and plant health. Sprouting typically begins in 3 to 7 days.
The worksheets include an experiment planning sheet, a side-by-side growth tracking chart, and either a results reflection (K-5) or a lab report template with a graph (6-12). It's a great match for Arizona's low desert, where fall and winter are prime growing seasons.
Join the growing community
Every kit purchase includes an invitation to Aardvark's Seed Planting For Little Hands, our private group for families using our kits. Post a photo of your soil cups, share which soil won, and ask questions when a seedling struggles. Arizona kids are growing alongside families in West Virginia and Arkansas, where the soil and weather are completely different, which makes comparing results even more interesting.
Turn this fall's rain into a science lesson
The desert just reminded everyone how much soil and water matter. Let your kids find out why with their own hands.
- Soil Science Experiment Kit (4 Pots) - Compare Growing Media: $39.90 (Grades K-5 or 6-12)
