Runoff from agricultural land is a major factor in the creation of dead zones. The nutrients end up in the ocean instead of staying on the farm. This not only produces algae blooms in the water it also leaves the land striped of vital resources. To compensate for this loss the farmers often apply more fertilizers which can also runoff, creating an endless loop. There are ways to reduce the amount of nutrients that are washed away, helping both the water and the land.
Planting crops in the fall after the main crop has been harvested. Their roots help to hold the soil and nutrients in place until spring when the farmer can replant the main crop.
Each type of plant has its own special needs. If the same crop is planted year after year it will us up all of the nutrients that kind of plant needs so more will need to be added. Changing the crop every year gives the soil time to rest. Some plants even add nutrients back into the soil.
Applying fertilizers when they aren’t needed or before it is going to rain results in more of the nutrients being washed away instead of going to the plants. Fertilizing in the spring instead of the fall helps to minimize runoff.
Having a buffer area between farms and waterways is a way to help to trap fertilizers before they can be carried off to the ocean. Strips of grass or other vegetation near streams can use up nutrient in the runoff.
Retention ponds are a place for runoff water to collect. This gives plants time to use the excess nutrients before they end up in larger water ways.
The runoff game
Materials: Sidewalk chalk, small individually wrapped candies or other small items such as pebbles (one per child), and a container larger enough to hold all of the candy.
Draw a river that is large enough for the children to walk down. Add smaller streams and creeks that branch off of the river. At the mouth of the river place the container, this will represent the ocean.
Each child (except one) will stand by the river, stream, or creek; they are a farmer and this will be the location of their farm. Give each child a piece of candy; this will represent the nutrients in the soil. One child will be designated to be the rain, when this child walks over to one of the farms and says “it’s raining” the child on the farm walks down the river and deposits the candy into the container. Since there is nothing to stop the runoff all of the nutrients end up in the ocean. This continues until each child has gone. Discuss what happened. Notice how a small amount of nutrients from each farm ended up being a lot when they collected in the ocean.
Discuss ways to minimize runoff and play the game again. This time when the rain comes to the farm ask the farmer how they can prevent runoff. If the child can give a solution the nutrients stay on the farm instead of going to the ocean and they get to keep their piece of candy.
After the game have the children draw a picture of their farm and how they would prevent runoff.