Saturated Buffers: What You Need to Know

June 1, 2017

Advancements in tile drainage technology have had a profound impact on the agriculture industry. With effective tile drainage in place it’s possible to improve your yields, soil, and the environment around you.

However, as with any improvement, there are unintended consequences or challenges. With tile drainage excess nitrates and phosphates can sometimes be carried off of fields into ditches, streams, and rivers, especially in early spring after the first major rain event. While these nutrients are a natural part of aquatic ecosystems, too much entering the environment at once can have negative effects such as excessive algae growth. One possible solution to this issue comes from the idea of saturated buffers.

What Are Saturated Buffers?

According to the United States Department of Agriculture (USDA), a saturated buffer is a subsurface, perforated distribution tile used to divert and spread drainage system discharge to a vegetated area. By utilizing saturated buffers, a portion of the drainage water is diverted into lateral drainage tile installed along the buffer. This helps to increase the shallow groundwater level and provide effective nutrient removal. Essentially, it diverts flow into a buffer that absorbs nutrients before they can enter streams and other water supplies.

How Do Saturated Buffers Work?

As shown in the images from Iowa State University Extension and Outreach (below), a conventional tile drainage system uses underground tile that takes excess water from the cropland and drains it into the nearest ditch or stream. With a saturated buffer, a second outlet for subsurface drainage is provided. By installing a water control structure in the main drainage outlet, the flow is diverted from the tile outlet to a lateral, perforated distribution line running parallel to the watercourse.

During periods of high flow in the tile system, the structure is set to bypass excess flow to the main drainage outlet. As the drain water seeps into the distribution pipe, the soil becomes saturated in the buffer area allowing vegetation and soil organisms to remove nitrate from the water.

What Are the Benefits of Saturated Buffers?

One of the biggest benefits of utilizing saturated buffers is the environmental positives. Every summer, the Gulf of Mexico experiences what is referred to as a “dead zone.” A high level of nitrate from spring rain flushing through the soil profile creates a low oxygen level situation known as hypoxia,
which causes an area to be unable to support living aquatic organisms. Saturated buffers could help to reduce this “dead zone” by limiting nitrate runoff into the Mississippi River basin. Using saturated buffers can also help the environment near your farm by removing sediment, phosphorus, and pesticides.

Effective tile drainage helps ensure optimal growing conditions for your crops. When used in combination with CRP filters or riparian buffer strips, saturated buffers can help farmers maintain an optimal water supply for their crops to increase yields but still rest easy that using the tile drainage system will not have a negative effect on the environment.

If you would like to know more about saturated buffers and whether your farm could benefit from them. Please contact one our Farmland Professionals in the Hertz office closest to your farm. Call Hertz at 800-593-5263 or visit hertz.ag.