Dan Jaynes, Research Soil Scientist with the National Laboratory for Agriculture and the Environment (USDA-ARS), hit the high points on saturated buffers last week in the latest Iowa Learning Farms webinar. Watch the archived version now.
Saturated Buffer Effectiveness and Price Per Pound of N Removed
Saturated buffers can divert about half of the water coming out of a tile outlet (red bars). From this diverted water, the practice can remove between 8-84% of N (blue bars). Saturated buffers costs about $1 per pound of N removed. The practice ranks similarly to other nitrate reduction edge-of-field practices. A comparison table is shown below.
Recent Updates to the Conservation Practice Standard
See the most recent conservation practice standard for a saturated buffer here. Watch the presentation to hear the discussion on specific changes.
Saturated Buffer Design
Saturated buffers should be designed to treat 5% of the drainage system capacity, or as much as is practical based on the available length of the vegetated buffer. To determine the drainage system capacity, use this excellent tool from the Illinois NRCS. Option 1 (determining capacity using slope and diameter) is the most common option used if limited information is available on the drainage system.
Frequently Asked Questions You Should Know
If you field questions from producers about saturated buffers, make sure you know the answers to these commonly asked questions. Dan covered his list of FAQs:
- Are we trading a water quality problem for an air quality problem?
- Does denitrification account for all of the nitrate lost?
- How wide should the buffer be?
- What should the buffer vegetation be?
- What about multiple distribution pipes?
- What about roots plugging distribution pipes?
Roots Plugging Distribution Pipes
On the issue of whether roots plug distribution pipes, Jaynes says that, generally, the answer is no. For a more in-depth look, here is a great video of a look inside a saturated buffer distribution pipe.
To learn more about site suitability for saturated buffers in your local area, explore the ACPF Saturated Buffer Viewing Tool. The suitability of an area in central Iowa is included below. This can be a great tool to determine potential saturated buffer sites (followed by a trip to ground-truth site conditions).
If you want to learn the latest information about saturated buffers, tune in to the archived webinar!