The water that flows across a plot of farmland ends up in one of three places. First, some of it will enter the soil, where it is absorbed by the crops and used to facilitate growth. The rest of it will remain in the soil as groundwater, be lost to evaporation, or flow from the farm into the surrounding area.

Water from rainfall and irrigation tends to return to other nearby water sources, flowing downhill and entering lakes, rivers, reservoirs, and the ocean. Water that has flowed from a farm, however, picks up a number of harmful substances as it does so: the byproducts of fertilizer use, such as nitrogen; dirt and other sediments; and chemicals, such as pesticides. Each of these can enter the environment and create problems for both humans and wildlife.

Nitrogen is a vital nutrient in agriculture, necessary for plant life to thrive. However, when too much enters the environment, it can cause algae and other phytoplankton to grow out of control, leading to a depletion of oxygen and other resources. This can devastate biodiversity in an area, as the algae becomes the only thing that can survive.

Similar to the vegetative buffer zones mentioned above, cover crops can serve as a barrier while also providing a habitat for critical local wildlife. While buffer zones are made up of naturally grown native plant life, cover crops are non-cash crops planted and cultivated by farmers for the specific purpose of protecting the environment from agricultural runoff.

Cover crops provide a variety of benefits when it comes to reducing runoff: First, the roots of the plants serve as powerful natural anchors for the soil, preventing the erosion that would otherwise occur (excessive erosion is generally the result of loose, uncompacted soil). The plants themselves also serve as natural “sponges” to absorb contaminants. They eagerly absorb nutrients, such as nitrogen, and chemicals, such as fertilizers, while also diluting pesticides to the point where they do not cause undue harm to nearby wildlife.

Cover crops also have a beneficial effect on the soil itself, potentially reducing the need for some of the contaminants that would otherwise end up in runoff. For example, as these crops go through their natural life cycle, they “recycle” the surrounding soil and return natural nutrients to it. By providing a home for beneficial pollinators such as bees and butterflies, cover crops can also provide a boost to the health of surrounding plant life, including agricultural crops.

One of the most crucial methods for reducing and preventing the negative environmental impact caused by runoff is to reduce the use of chemicals in the first place. The responsible use of both fertilizers and pesticides is something that all farms should focus on, particularly if they border environments that are vulnerable to contamination from runoff.

While fertilizers are crucial for the productive growth of healthy crops, the fact remains that they are often overused. Farmers can reduce their reliance on fertilizers by using more natural methods of encouraging crop growth. For example, crop rotation ensures that soil is kept viable and healthy by continuously switching out the type of crops that are grown on a given plot of land. This method works because different crops have different nutritional needs. This method also helps to reduce the need for pesticides, as it disrupts the life cycles of harmful pest insects that would otherwise take hold.

Farmers can also reduce their reliance on fertilizers and pesticides by using software to track crop growth cycles. This allows them to utilize chemicals at the moment they have the greatest benefit, vastly increasing the efficiency of their use and reducing the amount needed.