Moist Soil Management ‘How To’ Guide
Defining moist soil
Historically, moist soil wetlands were areas that had some type of natural disturbance (beavers, floods, fires, high winds, etc.) that created openings in bottomland hardwood forest. These openings would grow in seed producing annuals that prefer disturbed moist soils.
Before modern agriculture and moist soil management on man-made impoundments, this is most likely where the largest concentrations of waterfowl would have occurred on the pre-Columbian landscape. Native Americans may have been managing for waterfowl as well, attracting large concentrations to their fields. I have never been able to locate any research regarding this topic, but it would not surprise me if they did some form of moist soil wetland management or even growing crops for waterfowl to improve their hunting grounds.
Universal moist soil requirements
Every impoundment is different. Some areas have flood control structures and some beaver dams. Each unit will have a different seed bank and a different hydrology based on its elevation, drainage, soil type, etc. This results in different management requirements as well as different plant responses. How to manage each individual unit is unique to the site, but there are several steps that are universal when it comes to moist soil management.
Soil Disturbance
Every moist soil area needs some form of disturbance. We use disking as our primary disturbance, but fire and other methods are options. By disturbing the soil we scarify the seeds and create bare soil that allows for the germination of seed producing annuals. We can achieve soil disturbance by planting a crop like millet, then manage for moist soil the following year. Periodically rotating units from crop plantings to moist soil management increases the diversity of a wetland complex while reducing operating cost. If the moist soil drawdown fails the following year, replanting millet is always an option. Herbicides like 2-4D can be used to reduce non-desirables e.g. perennial smartweed, cocklebur, and sesbania and often times result in good moist soil regeneration if other factors are in place.
Drawdowns
Water drawdowns are key to generating good moist soil management. If drawdowns are early (March-June) and slow, good moist soil response will typically occur. However, the weather does not always cooperate. On our farm, we experienced the river flooding up until June 16th which kept us from having early drawdowns this year. As a result, we water sowed all our impoundments in rice on June 18th.
Some years, allowing moist soil wetlands to evaporate can result in extremely good moist soil response, but again, the weather does not always cooperate. At our farm, heavy rains from tropical storms in late summer can keep units from evaporating. However, if rice was planted, this can produce a bumper crop in our units. But, if possible, early and slow drawdowns with recent soil disturbance will result in the best response. Later drawdowns and different rates of drawdowns will result in different annual moist soil plants. The key takeaway here is to keep your drawdowns slow and early.
The more control of the water coming off and on the better. If we can get water off early, but we lack precipitation following the drawdown to keep the soil moist, we can flush the impoundment with an irrigation source. Having good drainage plus a water source makes for the best moist soil impoundments, however irrigation and good drainage are not always present on our properties or leases. As a result, we must play the hand we are dealt, rolling the dice with drawdowns and crop plantings.
Moist Soil Management Checklist
Below is a checklist I created for land managers to use on their farm or lease. Remember, each site is different, but this can be used as general rule of thumb. Whether you answer yes or no is dependent on the site and your budget.
Does the Unit have adequate drainage? YES- Move to point 2. NO- Move to point 3.
Does the unit have irrigation? YES- Move to point 4 & 6 NO- Move to point 4 & 5.
If drainage of the unit cannot be improved, depending on how much and how quickly the unit can be drained with varying amounts of precipitation, late planting of early maturing crops can be considered as well as allowing the unit to evaporate after a soil disturbance the previous year.
If relatively good drainage can be achieved early in the growing season, consider an early and slow drawdown. This will typically result in good penn. smartweed, millets, etc. Some years late maturing crops like rice or milo can be planted if adequate growing time prior to first frost is accounted for. If crops or drawdowns fail due to flooding, drought, insects, etc. we can often be left with a unit of coffee bean, horned beakrush and other non-desirables. If this is the case move to point 5.
Plant early maturing millet and or buckwheat in unit. Disc/disturb soil prior to planting, getting your ground ready for a good moist soil drawdown the next season. This will provide good duck food that season while preparing the unit for moist soil management the following season.
If the unit has both good irrigation and drainage, we can reliably plant crops and or manage moist soil with less risk of failure. Depending on our budget we can grow row crops or manage for moist soil effectively by having good control of the hydrology. The irrigation source allows us to keep the soil moist, flush the impoundment for non desirables, encourage the growth of seed producing annuals and to irrigate our crops during the typically drier months of late July and August.
wrapping things up
Remember, this is a general rule of thumb. Every site is different and when growing crops or managing for moist soil, there are tons of factors that can come into play. Every year is different and experience is the best teacher. Try to keep expectations within reason of your inputs. Don’t expect 200 bushel rice and corn on your first try. You will quickly learn that farming is a lot of work and mother nature shows no mercy.
If you’re intimidated by growing crops like rice and corn, start with millet and moist soil. You can attract and draw lots of ducks with millet and or moist soil. Talk to your ag extension when starting. Take soil test and talk to farmers and other locals who may have tried different crops in your area. That’s where you will learn the most about growing duck food in your region. And remember, you will learn much more from failure than success in moist soil management!
additional reading
A great reference for moist soil management is the Wetland Management for Waterfowl: A Handbook[1]. I would keep a copy of this on hand when you are starting to experiment. Another reference I use is from the USFWS[2] and has plenty of useful information for moist soil management.
[1] https://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs142p2_016986.pdf
[2] https://www.fws.gov/columbiawildlife/moistsoilreport.pdf