One of the people I often think about is Ernie Aust and his unwavering commitment to soil & water conservation. Ernie was one of my favorite Area Conservationists during my 14-year NRCS career. He loved to question conventional wisdom and was always willing to look at different perspectives; indeed a rare trait. I remember a lot of lively conversations with Ernie, but the most memorable was a discussion about grassed waterways and their maintenance.
We agreed the conventional wisdom is to mow grassed waterways. In general, mowing grassed waterways results in less sediment being deposited, thereby prolonging the life of the waterway. Mowing, especially in the spring, is thought necessary to prevent the grass from trapping the sediment that results from spring rains.
While debating the pros and cons of mowing, my initial position was, “of course, farmers should mow waterways. The objective should be to extend the life of the waterway as long as possible so farmers can maximize the benefits of cost-share dollars spent. What other possible objective could there be?” “What if,” Ernie said, “our goal is to reduce silt moving downstream, along with controlling ephemeral erosion?” Ernie suggested that “to mow or not to mow” should depend on the resource objectives – not on conventional wisdom.
It was then that I realized that grassed waterways could solve multiple resource objectives. They could be used to reduce ephemeral erosion, they could be used as a practice similar to a stream buffer to trap sediment, or they could be used for both. Always the forward thinker, Ernie was realizing the impact of precision conservation long before the term was coined.
Ernie’s point was that if we want to reduce sediment downstream, maybe we should design and maintain waterways to trap as much sediment as possible. I know, I know, most conservationists will say the producer should have adequate upland treatment in place before installing a waterway and that waterways should be used to reduce ephemeral erosion, not trap silt. But, why shouldn’t we use grassed waterways in ways similar to how we use stream buffers —to intercept sediment, nutrients, pesticides and other pollutants?
A farmer might be concerned that using a grassed waterway for a filter could lead to more maintenance costs. But, maybe we should calculate the cost-benefit of using grassed waterways to trap sediment, thereby keeping the “dirt” on the farm where the farmer can use it. Of course, it would be best to improve upland treatment and then use the grassed waterways to control ephemeral erosion. However, if the choice is to simply install a waterway that allows the sediment to move downstream or be trapped in the grassed waterway, maybe we need to rethink our strategy.
In his own unique way, Ernie was an early pioneer of precision conservation and I am honored to have had him for a supervisor. All conservationists should have the opportunity to work with someone like Ernie. It is this questioning of conventional wisdom that will allow us to accelerate the adoption of real precision conservation.
Les, you are correct. There are more objectives for grassed waterways than just ephemeral erosion and sediment trapping. As you said, there are other objectives like bird habitat.. If you do enroll in CSP, wildlife habitat may be the over-riding objective that dictates when, and if, you can mow. USDA program take more a cookie cutter approach and try and solve multiple objectives.
As with any program, the farmer needs to insure their objectives match the program objectives of the government’s. If your objectives do not line up, as a landowner, your best course of action may be to install the waterway without enrolling in any government program. As a landowner, this provides you with the flexibility to maintain your waterway to meet your objectives.
The question of waterway mowing on our farm has been more about the requirements of CSP to maintain bird and wildlife habitat by not mowing, vs the possible benefits of mowing to maintain a healthy and full sod cover in the waterway.
Tom—this addresses a question I got from a fertilizer dealer in western Illinois early this morning. He was trying to assess the value of cover crops in saving nutrients as well as soil. While not directly the same, I related the value of grassed waterways for that purpose as well. Then I get your post…..right on time!
Ernie is an old friend of mine. If you see him, please say hello from me. John
Tom, I too was impressed with Ernie. As far as waterways go, there are a lot of variables in the design of a waterway. Should you mow, let it grow, make it shallow and wider, or make it narrow and deeper. As you said, we often look at preventing ephemeral gully erosion with waterways, where terracing or tillage may not be practical. If you slow the flow down (widen the channel or not mowing), you keep the pollutants on your land. If you mow or narrow the channel, you speed up the flow and all the pollutants end up in the lakes and streams. And if you speed it up too much, you end up with more gullying. Another benefit it to wildlife. If the waterway is planted to native grasses, it becomes beneficial to song birds and game birds. I’ve always found waterways a very challenging conservation practice.
George, you make a great point. Waterways are a very challenging practice. I think the reason why they are so challenging is that through modifying their design they can address so many resource objectives. Waterways should not be addressed in a cookie-cutter fashion, but, on the other hand, we need to figure out how we can significantly increase our implementation of waterways. We have to install them at a much faster pace than we have in the past. Again, it is all about precision agriculture…