AgLab: Science for a Growing Mind

Welcome to AgLab, ARS’s website dedicated to students, educators, and parents who are interested in exploring the intersection of where food meets science.

The Agricultural Research Service is the premier agricultural research agency in the world. We find solutions to agricultural problems that affect Americans every day, from field to table.

Geared toward k-12 students with an interest in food and science, AgLab offers a variety of content to promote a greater understanding of how agricultural research is helping meet the food, fiber, feed and fuel needs of a growing world population while also safeguarding our environment and natural resources.

Check back often to view new AgLab content, including videos, nutrition tips, science projects, apps and more.

Soil Amendment Experiments

About the Experiment

Plants need suitable conditions to thrive and soil provides a physical medium for seeds to germinate and allow roots to explore, thereby anchoring the plant in place. Water and nutrients are needed along with an abundant supply of sunlight! There are two main sources of nutrient applications to soil – 1) inorganic fertilizers that can be purchased commercially and 2) organic amendments such as composted materials and discarded, natural foods. This experiment will focus on organic amendments.

Let's Find Out How With This Project

	Details Ages - 5-12 (parental supervision required)
	Time - 1-2 hours at start-up, few minutes a day for 6+ weeks
	Difficulty - Moderate

 What You'll Need

• A suitable space to grow your plants for up to 6 weeks. This can be a table next to a large window receiving lots of sunlight or a flat area outdoors that won't get disturbed and has plenty of sunshine.
• Containers to grow your plants. These can be of different sizes and shapes, but should be sturdy enough to hold moist soil for the duration of the experiment. They could be as large as 5-gallon buckets or as small as 6-ounce plastic drinking cups. Containers should have drainage holes on the bottom to allow excess water to drain from the soil. You will also need a large cookie sheet or similar item to hold the cups as well as the drained water.
• Seeds. Consider various broadleaves such as turnip, sunflower, or beans or some common grasses like wheat or corn. You may even consider radish, spinach, or collards, which are short-duration vegetables that can mature and be edible within 6 weeks.
• Soil. Enough to fill all containers. Any soil can be used, including soil from your garden, dirt from your backyard, or sand.
• Organic materials to amend the soil. Dried grass clippings, dried leaves, used coffee grains, egg shells, compost, cardboard egg containers, leftover fruits and vegetables. Any of these will do.
• Spreadsheet to track progress of the experiment.

Let's Do This!

1. Choose 1-3 organic amendments. You will also have a "soil only" plant, which will be the control experiment. For each experiment, you'll need three plant test subjects. For example, if you choose coffee grains, eggshells, and grass clippings, you'll need a total of 12 test subjects – three for each amendment and three for the control. You can also add a fifth test subject that includes a mixture of all three amendments.

2. Individually mix each organic amendment (generally about 2% of the soil weight should be of the amendment) with soil thoroughly and weigh out the desired amount of amended soil into the three containers (make sure you label the containers!). The containers should be 3/4th filled with the amended soil. Add soil without an amendment to the three control containers.

3. Place seeds into a small indentation of the soil in each container. Note that some seeds may not germinate or may die for various reasons. Therefore, plant 5-6 seeds for each container and thin to 3 plants per container a few days after emergence.

4. Add water to each container and allow excess water to drain through holes at the bottom.

• Note for more controlled experiments: You can determine the water-holding capacity of the soil before planting seeds by soaking the containers with full water and allowing ½" of water to accumulate in a tray in which the containers are held. After 1 day of soaking, weigh the containers and this will be the maximum weight of the container plus soil. If you weigh the container without soil and the weight of the container plus dry soil, you will be able to calculate with accuracy the soil water content at saturation. Plants often perform best when soil is maintained between 40 and 80% of saturation. As an example, if the container weighs 10 g and the dry soil is 500 g, then the total weight after soaking at saturation may be 660 g.

5. Place the containers in a room temperature environment not exposed to direct sunlight until seedlings emerge. Once most seedlings emerge, evaluate the need to thin out excess plants and then place in more direct sunlight for allowing plants to grow vigorously.

6. Water plants according to their needs. This could be once per week initially when plants are small to once per day when plants are large and growth conditions are most favorable. The plants will wilt and die if not enough water or too much water is provided.

Measurements to evaluate the experiment

7. There are a variety of measurements you can make to evaluate the results of the experiment. Create a spreadsheet and make a column for each container in the experiment and each row or line of information can be an observation that has a response recorded for each experimental unit

8. Take weekly photos to create a visual documentary of plant growth and changes

9. Simple qualitative measures might include color of the plant, tendency to wilt, stopped growing, has odd-shaped leaves, attracted by insects, etc. Simple quantitative measures might include days to emergence, number of seedlings emerged and height from soil at 1 week, 2 weeks, etc. up to the end of the experiment. Size of leaves could be determined periodically. Sensor measurements of leaf color can provide a quantitative evaluation of plant health.

10. After 6 weeks, consider whether sufficient evaluations have been made, or if plants should be evaluated further for product tasting (in the case of leafy greens), bulb growth (in the case of radish or turnip), or cutting plants at soil level and making measurement of wet weight and/or dry weight (after placing cut plants separated by container into paper bags and placed in direct sunlight to dry for several days or in an oven at 150 F for a day or until dry.

What did you learn?

1. Which amendment produced the most growth potential? Why do you think some amendments are better than others?
2. How did the different plants with amendments compare to the control plants?
3. Did the plants taste different?
4. Where there any color or size differences among the plants?
5. Which plants grew fastest, which were the slowest growing?
6. Do you think positioning of the plants and their distance to sunlight mattered?
7. Which week had the most growth for the bulk of the plants?
8. Do you think the experiment results would be different if another seed type was used?
9. Could you grow other plants with organic amendments alone?
10. Would you like to be a life-long gardener or farmer? Why/why not?

Black Light Experiment

About the Experiment

Luminescence is a source that gives light without heat. There are many different types of luminescence. In this experiment we will be looking at Fluorescence in food and plants. Fluorescence is an optical phenomenal that occurs when the atoms inside a fluorescent material become excited after absorbing light energy (such as UV-light) and the material emits visible light. The visible light is emitted as the energy of the material are returned to normal. This all takes place in less than a second. The visible light given off are tiny particles called photons.

Let's Find Out How 

	Details Ages - 5-12 (parental supervision required)
	Time - 15-20 minutes
	Difficulty - Easy

 What You'll Need

• Scotch Tape
• Flashlight (can be $1 flashlight)
• Clean spray bottle or water bottle
• Blue and Purple sharpie pen
• 4-5 food items (orange juice, organic honey, milk, eggs, olive oil)

Let's Do This!

Making Your Own Black Light

*Safety - Never shine a UV-Visible light directly into your eyes or the eyes of other people or animals.

1. Place a layer of tape (2-3 pieces) over the flashlight lens all in the same direction. Make sure the flashlight is off.

2. Color the layer of tape with the blue sharpie.

3. Place a layer of scotch tape perpendicular (90°) to the layer of tape you placed in step 1.

4. Color the layer in step 3 with the blue sharpie.

5. Place another layer of scotch tape perpendicular to the layer of tape you placed in step 3.

6. Color the layer in step 5 with the purple sharpie. Turn on your flashlight, which has been transformed into a fluorescent light!

7. Observe the Fluorescence of Food and Plants

Using the UV-light you just made, look at the fluorescence of different food items and plants around your house and yard. Some items will show fluorescence and some items will not. Below are some pictures of fluorescence of items and a list of some items that will fluoresce.

Other things to try

• Milk
• Ketchup
• Bananas
• Oranges
• Spices

ARS Scientists Safeguarding Food with a New Test Kit

A test kit developed by ARS scientists can help protect food from mycotoxins—toxic chemicals produced by certain molds. 

ARS Takes A World View Of Food Safety

The safety of the food supply has become an increasingly visible global public health issue. This podcast talks about ARS’s role in keeping food safe to eat. 

Audio Podcast: (3 min. 9 sec.)   mp4  |   Transcript

Reducing Herbicide Spraying

In Mississippi, agricultural engineers teamed with plant physiologists to explore using camera-mounted drones to reduce herbicide spraying where and when it’s not needed, reducing costs and the risk of environmental harm.

Visit the Crop Production Systems Research Unit to learn more

* Image courtesy of Getty Images

The Egg-Zact Way To Store Eggs

An ARS scientist provided clear evidence that storing eggs in the refrigerator is the safest way. That might seem obvious, but many other countries don’t refrigerate their eggs because they don’t see a need to.

In a study of 5,400 eggs stored in different conditions, ARS showed that refrigerated eggs remain Grade A quality for 15 weeks, while unrefrigerated eggs went from Grade A to B in just a week  Learn more about "How We Store Our Eggs—and Why"

Better Bagged Leafy Greens

When you’re in a hurry but still want a healthy meal, bagged salads are a great choice.

ARS food safety scientists performed groundbreaking research on how to wash leafy greens and other produce most effectively during processing. Their work led to industry guidelines to prevent pathogen cross-contamination and spread during the washing process. Read "Keeping Bagged Leafy Greens Safe and Nutritious for Human Consumption" to learn more.

Soil Erosion Experiments

About the Experiment

Soil is a living and life-giving natural resource that promotes plant growth, makes a habitat for living things, and stores water.  Soil is mixture of organic matter, minerals, gases, liquids, and organism, working together to support life.

The process of weathering is the transformation of rock into soil through physical, chemical, or biological processes. Erosion is the next step in the process where soil is displaced to another location through movement caused by water, wind, and/or ice. Some of the greatest natural wonders of the U.S. including the Grand Canyon, Natural Bridges National Monument, and Devil's Tower were carved and transformed in part by erosion and deposition of soil over time.

Let's Find Out How With This Project

	Details Ages - 5-12 (parental supervision required)
	Time - 15 minutes + few minutes a day for 3 days
	Difficulty - Easy

 What You'll Need

• Soil or Dirt of various colors and types such as sand, silt, and/or clay
• Trays or containers with four sections (aluminum or lined cardboard box)
• Clean spray bottle or water bottle
• Clear cup or measuring cup
• Water
• Pen ad Paper / Journal

Let's Do This!

Soil Experiment #1

1. Gather up a handful of four different types of soil. This can be dirt, sand, clay, silt, chalk, etc.
2. Place the soil types in different sections of your tray.  Soil can be dry or add a little bit of water to build a landform.
3. Draw a picture of your soils and describe the texture, color, and shape of each.
4. Use a spray or water bottle to dribble drops of water on each soil to represent a light rain.  Record your observations, what is happening to the soil, how is it changing, if at all?
5. Now, pour a cup of water into each soil tray to represent a heavy rain.  Record your observations, what is happening to the soil, how is it changing, if at all?
6. Leave the tray in a secure location outside for three days, preferably when there is no rain expected. Observe the soils the same time each day and record your daily observations as it relates to erosion by wind.

Soil Experiment #2

1. Fill one cup with water.
2. Collect dirt clumps from two different soil types (see above).
3. Draw a picture of the dirt clumps and write a description of each that may include but not limited to diameter, color, texture, etc.
4. Drop one clump of dirt in the cup of water and record your observations at it relates to how the water erodes the dirt.
5. Repeat step 4 with the other dirt clump and cup of water and record your observations.

Reflection Questions

1. How did the different soils react to the light rain, the heavy rain, and the wind?
2. What happened to their composition?
3. Did their color change?
4. How did the soils maintain the water over the course of three days?
5. How did the soils look and feel compared to the first day?
6. Which soil(s) do you think is best to handle heavy rains or high winds?
7. If the soils… they withstood weathering and erosion well. By comparison, if the soils…they were more vulnerable to soil and erosion.