Disking, Spraying, or Fire? The Art & Science of Wetland Management
The wetland manger has many tools in their arsenal when managing for moist soil. When considering all our options for disturbing a moist soil unit, it could be summarized into the following categories: mechanical, chemical, flooding and fire. The question for any wetland manager would then be, ‘what methods should I use?’ This is hard to say being that every wetland will be unique with its soil type, flood regime, seed bank, and a whole host of other variables that influence the resulting moist soil plant species presence and abundance.
So how do we find the best methods? Observation and experimenting are how we can determine what methods work best. After learning the science of wetland management, much of the management work will become intuitive. The landscape becomes a canvas and these management methods become our paintbrush. In the following sections we will cover these management methods and how we are utilizing the science of wetland management to create ‘wetland art.’
Observation
Continued observation and record keeping allows a wetland manager to see what worked and what didn’t. By observing our results, we can better implement effective management practices each season.
One of the first things I noticed on our property was that anywhere there was bare soil within the flood plain/bottoms, moist soil annuals would dominate those areas. Roadsides, recently disked fields, hog rooted areas, and sometimes burned areas would contain large amounts of annual moist soil plants. Overtime, these areas would start to become dominated by later successional vegetation such as blackberry, green briar, and sweet gum seedlings. Hence, this is what we need to manage for moist soil plants; moist & bare soil. The following methods create those bare soil conditions.
Prescribed Fire
Prescribed fire is a an extremely cost-effective tool to set back succession. Annual moist soil plants dominate in recently burned areas that received more flooding during the spring, while areas that lacked in flooding resulted in annuals such as marsh elder. Marsh elder is a desirable native annual plant for bottomland ecosystems, but in the areas that we are managing for duck food, it is an undesirable. Therefore, flooding can be used to discourage the growth of undesirable annuals after a prescribed fire within a unit. Burning a unit to remove previous year(s) growth, followed by a flush of water to the impoundment could result in an excellent moist soil stand.
Mechanical
Tools used to create a mechanical disturbance include but are not limited to disks, rice rollers, cultivators, and bush hogs. I have found over the years that a disk is typically the best tool for moist soil management. Something I am looking into purchasing in the future is a rice stubble roller. This would allow me to incorporate the stubble from previous years rice or moist soil crop into the soil while smoothing out the ruts and creating firm and even bare soil. This may become my new favorite mechanical disturbance tool along with disking.
Something to consider with mechanical disturbance is that a tractor is most likely needed for large impoundments and of course the attachments needed to incorporate the disturbance. This is a large capital expenditure for any property, but the uses of a tractor and its attachments will meet just about any of your duck farming needs. It is my number one tool on the farm. Excavators and dozers build the impoundments, but tractors and their attachments manage the impoundments to create duck food. If a tractor is out of your budget, UTV and ATV attachments can be used with the same results on smaller wetlands.
Chemical
Herbicides are extremely useful when it comes to managing moist soil. I have found that in some units, I can encourage the growth of moist soil plants without mechanically disturbing the soil for several years by using herbicide annually. By spraying a herbicide like 2,4-D, I can remove broadleaf undesirables i.e. sesbania, perennial smartweed, and cocklebur while encouraging the growth of desirables.
For instance, in one of our units that we plant Clearfield rice, the lower elevations typically remain wet until they dry in late summer. These areas were sprayed while wet with 2,4-D in 2020 to remove the dominating perennial smartweed and water primrose. 2020 was a very wet year and the higher elevations within the unit flooded the sprouted rice and resulted in excellent rice yields, however the lower elevations never dried.
This year (2021) was the opposite climatically. We had a very dry end to summer and the lower elevations evaporated and resulted in excellent moist soil stands. The herbicide application the previous year removed the matt forming stands of perennial smartweed and water primrose resulting in a bare soil that sprouted in moist soil annuals as the water evaporated slowly off the unit. The higher elevations planted in rice did not perform as well due to the dry summer, but broadleaf signal grass, panic grasses, and millets did very well in those bare soil areas because of the herbicide applications. Herbicides can reduce hours spent disking on our equipment, while creating viable moist soil yields.
Flooding
Flooding is what lubricates the previously mentioned methods. Various rates and timing of inundation greatly affect moist soil species presence, abundance, and yield. Every year is different with precipitation timing/amounts and how we manage our disturbance in coordination with these weather events and timely irrigation. Early drawdowns of water result in the best moist soil response, but late evaporating drawdowns can often result in extremely diverse stands with high yields. In many of our units, early drawdowns are not possible some years due to the above average precipitation that we have been experiencing in recent springs. This is where experimenting with different methods and observing the results will be the key to success. We can run experiments in our units, observe the results and try to see what we can do to improve our results.
Intuition
Trust your gut when it comes to moist soil management. I have observed wetlands throughout the years and that storehouse of conscious and unconscious knowledge typically results in me knowing what to do at the right time without thinking too much about it. There is not an exact answer to any wetland management issue you may have. There are typically several ways to solve a problem within a wetland unit. This is where the art of wetland management comes into play.
Look at your property as a canvas and you, the manager, as a painter who is in the process of creating something to enjoy and admire. You, the artist, are creating diverse habitat for a multitude of species. Most “mistakes” can be fixed, and we often find that our mistakes can turn into new solutions.