Flooded Pasture: Species and Seeding Options

Eric Mousel, Forage and Alfalfa Specialist, Millborn Seeds Inc.
605-690-4974, ericm@millbornseeds.com

My last article discussed the impact that flood waters have on pasture soils and some thoughts on what a person should do to revitalize those soils. I listed several species that can tolerate soils that have been impacted dramatically by flood waters.

But what about pastures that flooded out, but the soil tests come back indicating that the soil is in fairly good shape? Let’s look at some options for when it comes time to renovate or reestablish those pastures.

Wet vs. Dry

The first thing to think about when evaluating what type of grass to seed into a grass stand that has been damaged or if you are starting completely over is whether the pasture is normally a fairly wet area or if it just flooded out because of the high standing water from this spring.

If the site is normally a wet area, consider using a Garrison creeping foxtail which can withstand being underwater for 60 days or so without affecting it too much. Reed canarygrass is another species that really likes a lot of water. Although it is pretty decent quality forage early in the year, it tends to get pretty coarse later in the summer and doesn’t have a lot of feed value. You may have to hedge your bets a little and seed a mix of both if the pasture is pretty wet in some areas and just occasionally wet in others.

You may have gotten a big flush of Reed canarygrass once the flood water receded, but be aware that it won’t grow very well in areas that aren’t wet all of the time. So as the soils start to dry out, it will start to disappear and be confined to wet areas. The options are to over-seed the reed canarygrass regrowth to get some other grass species started or just wait until the canarygrass starts to disappear and then seed a mix that is more conducive to the normal soil conditions.

If you are seeding an area that is not normally very wet, I would recommend a mix with some orchardgrass ,pubescent wheatgrass, tall fescue, and meadow brome. This is a very nice mix for haying or grazing because none of these species get very coarse, especially if they are harvested at appropriate times. If you live a little further west (west of Hwy 281) I would substitute the orchardgrass for intermediate wheatgrass and/or Canada wildrye to improve the drought tolerance of the stand.

Seeding method

The next big thing to consider is the best seeding method to use. If you are completely reestablishing the pasture, the need to do a full tillage treatment is going to depend on how bad the weeds got after the water receded. If you didn’t get a lot of weeds, you can either no-till or broadcast seed direct with little or no tillage. Drilling is the best but that isn’t always feasible for everyone. Blowing seed on with a floater and roller packing has resulted in successful stands for a lot of guys so that certainly is an option.

If the weeds did get bad, you may have to consider tillage to reduce the amount of residue that may plug up the drill and to help with weed control next spring. Again, drilling seed in is best, but broadcast with a roller pack will work.

Seeding depth

If you do use a conventional or no-till drill, seeding depth is critical. Grass seed is not like wheat. Grass seed should only be seeded at a depth of ¼ to ½ inch. Any deeper and the seed will likely germinate, but won’t be able to reach the soil surface, thus you get a really spotty stand or none at all.

When to seed

Right now is not a very good time to seed grass. The risk is that the seed may germinate in the warm temps during the day but will freeze off at night and winter-kill. It would be a good idea to wait until the end of October or the first half of November to plant. Late fall plantings are generally very successful and will remove the risk of seed germinating and winter killing.

There is still time this fall to seed pastures damaged by flooding. Having the right grass species, seeding methods and timing will result in a successfully rejuvenated pasture for you. Give me a call and we will talk about your specific situation.

Thank you and have a great day!!

Flooded Pasture Soils

Eric Mousel, Forage and Alfalfa Specialist, Millborn Seeds Inc.

605-690-4974, ericm@millbornseeds.com

The first thing that has to be considered when figuring out what to do with a pasture that has been flooded out; is to consider what shape the soil is in. Flood waters that stand for long periods of time can really cause a lot of problems for your soil. These waters will bring in a lot of debris and salt and leave a lot of silt, sand and other trash.

There are three major things we need to look at when evaluating the soil in a pasture that has been flooded.

Alkalinity

When soil first becomes saturated, the pH will drop and the soil becomes acidic as a result of the production of organic acids produced through fermentation. However, after being saturated for an extended period of time, the soil will become alkaline as the pH rises. The rise in pH is partly attributed to the denitrification of nitrate (NO₃) to N₂ nitrogen.

Unlike soil acidity (low pH), where plant species will actually die from exposure, soil alkalinity decreases respiration and nutrient uptake in plants and therefore can cause depressed yields for forage species that are not adapted to a high pH environment.

Salinity

Soil salinity can be a big problem caused by flood waters. The inflow and subsequent settling of salt from upstream will at best leave a salt crust on the soil surface as flood waters recede. In the worst case scenario the soil profile will be completely saturated with salt.

The problem with salt in the soil is that it suspends when it is mixed with water, rather than dissolving. Therefore, the soil profile will contain a salt solution that plants have difficulty absorbing. In saline soils, plants will experience severe water stress even when adequate moisture is available because they cannot absorb the salt solution.

Soil Biology

Probably the biggest problem flood waters cause is upsetting the soil biology. Microorganisms that live in the soil are an essential part of plant growth. These organisms are largely responsible for making soil nutrients available for plant absorption. Many of these microorganisms that make nutrients in the soil available to plant life require oxygen respired by the soil to survive. Obviously, when a soil becomes saturated with water, these organisms will die off and only organisms that can tolerate the lack of oxygen will remain.

The change in soil pH as described above also will negatively impact many important soil organisms as will increases in salinity.

Soil testing

So, what do we do about soils in these situations? The first thing that needs to be done is to do a soil test to see what condition the soil is in. An analysis of N, P, K, pH, and salinity is probably all that is needed to start. Most of the available N has probably leached out and P and K availability will vary depending on site. As stated before, pH probably will be high, but you need to know how high so you can select species that will tolerate it.

Most any local CO-OP will conduct as soil test for you or you can contact me and I can arrange a soil analysis for you.

Solutions

Correcting these soil problems is difficult at best and depending on severity, not very economical. But there are some short-term (inexpensive) things a person can do to get the healing process started for your soil:

Alkalinity – if pH is above 8.0, action will need to be taken.

Add organic matter by growing an alkaline tolerant cover crop:

                              Turnips, radishes, lentils              

    Barley

    Alfalfa (moderate)

                                                               

                                Russian wildrye

                                Altai wildrye

                                Tall or slender wheatgrass

                                Smooth bromegrass

     Tall fescue

                               

Add sulfur to the soil solution by adding gypsum or fertilize with ammonium sulfate and retest periodically (worst case scenario).

Salinity

                Grow salt tolerant plants to remove salt from the soil solution over time:

     Turnips, radishes, lentils              

     Barley

     Sugar beets

                                Winter wheat

                                Sunflowers

                                Alfalfa (moderate)

                               

                                Russian wildrye

                                Altai wildrye

                                Tall or slender wheatgrass

                                Smooth bromegrass

                                Tall fescue

Soil Biology

The most important thing is to get something growing; anything that will stimulate the soil solution.

If your soil test comes back relatively normal…we’ll talk about that and what to do about flooded out alfalfa next time.

Thank you and have a great day!!

Flooded Pasture Renovations

Eric Mousel, Forage and Alfalfa Specialist, Millborn Seeds Inc.
605-690-4974, ericm@millbornseeds.com

For those of you that had pastures flood for extended periods of time this summer, you are not alone. It has been a very aggravating summer for a lot of people in South Dakota, but you can thank your lucky stars you don’t have land along the Missouri further south, it can only be described as disaster.

Even if you don’t live along the Mighty MO, the Big Sioux, James, and every creek, stream and tributary in between was out of its banks for a good portion of the summer. Prolonged exposure to the floodwaters caused a lot of acres of grass, alfalfa, and row-crops to be completely wiped-out or at least severely damaged.

I’ve looked at quite a bit of flooded pasture and hay ground this summer and fall and a lot of questions remain about what exactly to do with the acres that flooded out this year. The amazing thing is the response of different types of ground and vegetation to flooding. I’ve seen everything from complete vegetation kill to 7 foot tall weeds. The next few installments of SDR are going to deal with this topic specifically.

There are 5 major questions concerning flooded out pastures and hay ground:

1.       Did the flood water ruin the soil?

2.       What should I do with all of the sand and silt that washed in?

3.       Will the grass grow back or will it just grow weeds?

4.       Should I interseed new grass or alfalfa or do I need to start completely over?

5.       Should I drill new seed or blow it on?

I’ll get into specifics in the next few articles on SDR but suffice it to say that there is no cookbook recipe for managing the after effects of flooding. Each individual is going to have a unique situation based on soil type, vegetation, and severity of the flooding.

The solutions to regain full productivity of these acres also are going to be very individualized. Some will need to thicken the grass that remains, some will need to grow a cover crop to recondition the soil, some will need to start over.

Alfalfa acres also will need special attention in order to regain full productivity. Flood stress, disease, silting level, and age of the stand will all determine the appropriate management needed to restore full productivity.

So if you have damage to your grass pastures or alfalfa, you aren’t alone. Millborn Seeds Inc. will provide services to the entire 5-state region and beyond. Give me a call or email and let’s talk about what is needed to get your pastures and hay ground back to top productivity.

Thank you and have a great day!!