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Soil is a big part of your everyday life; your clothes, your food, and even your electronics have a link of some kind to soil. Soil is one of the most valuable natural resources on Earth, and yet it is being lost from the land at an alarming rate. Iowa has some of the best soil in the world, but it’s eroding at an average rate of 5 tons of soil per acre every year. That means an inch of soil is lost every 15-20 years—but it takes the earth 500-1000 years to replenish that inch of soil.
When rain falls on the land, it’s taking away more than just soil. Nutrients such as nitrogen and phosphorus are applied to farm fields to help crops grow healthily. If a lot of nitrogen is applied, plants are not able to use it all up, and the excess moves as nitrate through the soil into the groundwater. Phosphate, on the other hand, attaches to soil particles and travels with sediment. Both nitrate and phosphate can increase the nutrient levels in streams and lakes, which leads to high amounts of algae growth.
There are numerous conservation practices that can be used to reduce the amount of nutrients being lost from fields. Terraces, grass waterways, and buffer strips are effective in taking nutrients and sediment out of the water before it gets to the stream. No-till and strip-till farming leave plenty of crop residue on the surface of the soil to protect it from erosion. Using cover crops after harvest not only provides a living cover to hold and protect the soil, and these plants also uptake excess nutrients that would be vulnerable to leaching. Strategic placement of wetland areas can reduce excess nutrients from reaching streams, and also provide habitat for a variety of wildlife. These practices not only protect our soil and water quality, but add beauty to the landscape, as well.
Enhanced Learning Activities (recommended for Grades 4-7)
Iowa Core Essential Concepts and Skills for What's In Your Water? - The Farm
Next Generation Science Standards for What's In Your Water? - The Farm