soil exploration - Water Rocks!

soil exploration Grades 3-8 This activity was designed as a companion for the music video “Old MacDonald Had A Farm.”

Background This video takes the classic Old MacDonald song and showcases conservation practices that can be used on farms to protect natural resources. These conservation practices are important in building healthy soils and keeping water clean for Iowans in the present and future. In Iowa most of our farmland is producing crops such as corn and soybeans. We are the #1 producer of corn and soybeans compared to all other states in the US! However, intensive tillage of farmland leads to compaction, loss of helpful organisms and leaves soil bare and prone to erosion. By practicing no-till or strip-till (tilling only a strip for planting), the majority of the plant residue stays on the land to protect the soil. These reduced-tillage practices lead to less erosion and runoff, more infiltration, more organic matter to build healthy soils, and a better habitat for helpful organisms such as earthworms. The strategic planting of grasses (e.g. buffer strips) is another conservation practice that protects soil from erosion, while the grasses act as filters to remove pollutants from water flowing over the grass or underground through the root system. Riparian buffers use grass along the sides of a stream for bank stabilization and to slow down the movement of runoff water. The deep and dense root systems of switchgrass, bromegrass, and other perennial vegetation species can catch pollutants before they get to the stream. Grassed waterways provide paths for water to run off fields in areas where deep gullies would otherwise develop. Wetlands are unique ecosystems that provide habitat for many endangered plants and animals in Iowa. Wetlands act as the kidneys of the landscape because the plants, soils, and microorganisms remove nutrients and pollutants from the water passing through. In droughts, wetlands can sustain streams by slowly releasing water, and they act like sponges during periods of heavier precipitation. Cows and pigs are common livestock on farms in Iowa and we most easily relate them to the meat and milk they provide for our diets. There are different ways we can manage livestock to reduce the pollutants they might add to our waters. If cows are grazed over a small area for a long time, they will compact the soil and overgraze the grass. This can negatively impact the health of the soil, leaving it more prone to surface runoff and erosion that will pollute water. Livestock also shouldn’t be allowed unlimited access to streams because their pathways increase erosion and using the stream as a bathroom will lead to bacterial contamination. Manure from livestock can also be used to fertilize crops as they are a good and available source of nutrients. Like all fertilizers, however, it is important to be careful with applications. Applying more fertilizer than the crops need or applying before a rain will lead to excess nutrients leaving the field and polluting waterways.

© 2012 Iowa State University www.waterrocks.org

Soil is an important natural resource that all living things depend on. Plants are part of the food chain and they rely on soil to grow and survive. Soil helps control the flow of water during a rainstorm by absorbing and holding the water. Soil also acts as a filter; as water moves through, the soil can remove chemicals and excess nutrients. Soil is formed as rocks and minerals are weathered by wind and water and broken into smaller and smaller pieces. These pieces mix with organic material such as rotting animals and plants. The process of creating a single inch of soil can take 500 to 1000 years. Iowa was once a vast prairie and the dense vegetation contributed lots of organic matter to our soil, making it some of the most fertile in the world. One of the ways we lose this valuable resource is through soil erosion. Human practices can leave the soil bare and unprotected from wind and water erosion. The music video shows different examples of protecting the soil from erosion and ways to build healthier soil: • No-till and strip-till leave residue covering the soil as well as roots which hold the soil in place and allow for more infiltration pathways. Over time, this residue will also decompose and add more organic matter to the soil. • Cover crops protect farmland during the winter months when our main crops (corn and soybeans) are not growing. In addition to protecting soil from erosion, cover crops help to build healthier soil by adding organic matter and fixing nutrients. Common cover crops in Iowa are grasses such as rye, oats and winter wheat, which are planted after harvest in the fall and die or are killed off with chemicals prior to planting in the spring. • Buffer strips and grassed waterways are placed in areas that are especially sensitive to soil erosion. The dense root systems hold the soil in place and act as filters for sediment and nutrients.

Part 1 – Locate erosion in the area

Part 2 – Building healthy soil

• Take a walk around the school grounds with the students asking them to look for signs of erosion. Ask them why those spots eroded and not others. Look for areas of bare soil that will be prone to erosion.

• In this activity, students will make a delicious snack while learning the components and importance of our soil. Materials and instructions continue on the following page.

• Discuss how you could protect those spots from erosion. • As a class, plant flowers, grasses, or lay mulch in those areas and observe the effects.


Materials

Soil cups o Parent material = M&Ms o Subsoil = Chocolate Pudding o Topsoil = Crushed Oreos o Microorganisms (bacteria) = Sprinkles o Residue = Coconut o Earthworms = Gummy Worms Plastic spoons Short clear cups Napkins Bowls and spoons to serve from at each station

instructions Place elements in order with a sign at each. Students will build their soil cup from the ground up, adding each element to their cup in numerical order. As the students enjoy the snack discuss each element, how the rich topsoil is made, and what role organisms, residue and earthworms play.

1. Parent Material

2. Subsoil

The C horizon is partially broken bedrock. This rock material breaks down into smaller pieces to become soil.

The B horizon contains sand, silt, clay and nutrients that have leached from above layers.

3. Topsoil

4. Organisms

The A horizon holds most of the soil’s nutrients and is home to plant roots. Good farmland in Iowa can have an A horizon that is 3 feet deep 5. Residue The O horizon is a layer of decomposing organic matter such as leaf litter, compost, or previous years’ crops.

Bacteria and fungi help decompose organic matter and recycle nutrients to make them available for plants.

6. Earthworms Worms help incorporate organic matter into soil, recycle nutrients, and improve water infiltration.


Iowa Core Curriculum This activity fulfills the following Essential Concepts and/or Skills in the Iowa Core: • Science (Grades 3-5) o Earth & Space g Understand and apply knowledge of properties and uses of earth materials g Understand and apply knowledge of processes and changes on or in the Earth’s land, oceans, and atmosphere o Life Science g Understand and apply knowledge of organisms and their environments g Understand and apply knowledge of environmental stewardship • Science (Grade 6-8) o Earth & Space g Understand and apply knowledge of the structure and processes of the Earth system and the processes that change the Earth and its surface o Life Science g Understand and apply knowledge of the cycling of matter and energy in ecosystems. g Understand and demonstrate knowledge of the social and personal implications of environmental issues
