I'm on a large space of former cattle pasture in the PNW. At some time, likely over a half century ago, the pasture was tiled, red clay pipe.
The pipes have broken in places over time, opening up sinkholes as the free flowing water pulls any available dirt into the pipe and away.
I'm using the pasture for grazing sheep, and not planning on keeping any animals on it through the winter- but looking into remediating the pasture so it doesn't have the sinkholes and the resulting wet areas and wet area plants.
I've found one sure talking about taking care of this by breaking the pipe at the outflow end. I'm assuming this creates a choke point, slowing the flow of water, and allowing any silt to eventually clog the pipes. I've also considered maybe a single bar subsoiler, set deep enough (though this might be tough) could break the pipes in numerous places if I did passes at 10-20' intervals. In any case, once the water flow us stopped, the pipes essentially become the same as buried rocks, minimal problem.
Im on a minimal slope, and not receiving a lot of water from off-site or the road, so just need to work in infiltrating this water once it's no longer in a high speed rush. Thinking of using trees and planting to open up soil channels.
Anybody have experience (hopefully positive) with this kind of problem, without doing significant earthwork? (I have no problem with swales and berms)
It sounds like if you break the pipes, you'll have alot more sink holes. Are the pipes at least on contour? If they were on contour you could just put in your swales there. Im guessing they're not though, if they're designed to flow.
Maybe instead of breaking the pipes, use a tree round shaped down like a cork to plug the ends. Then tubes will act like a subsurface wicking water resivour, at least until they fill up with sediment. Then you don't have to break the pipes, and the water will most likely still drain out, only slowly enough it doesn't flush the sediment out with it.
If you want to get rid of the marsh plants, you'll need to change your soil dynamics to allow more aeration, and lower the water table. I'm guessing you have a high water table and a clay dominate soil. Swales can help lower the water table by giving the water somewhere to accumulate, but your long wet season will make it challenging to keep it dry enough to discourage the bunch grass.
Can you get free woodchips, and manures in bulk? Chip trucks can dump along the edge of your feilds in summer, and create the windrows for you. If you started windrow composting free woodchips or hourse manure. You could set the windrows up in your feild along the edge, or where ever the next windrow was needed. Once they are done composting and will germinate seeds, spread them out at least 8" thick and seed on them. That will help elevate your feild further from the water table, and smother the bunch grass on the old surface. Once the organic matter helps change your soil dynamics it will improve subsoil drainage, and with the new layer making the current water table 8 inches lower, it will be harder for swamp plants to establish themselves.
Thats my best suggestion, hope it helps.
posted 1 year ago
The "proposed" method (by Conservation experts turning tiled cropland into wildflower pasture) is to crush the ends with an excavator, at the same time you are doing other tilling/earthworks. Now, I'm not sure where the ends are. It's not like they pour out into a creek, but more disappear into a jumble of forest and brush. I can see how crushing them would cause the pipes to clog over time with sediment, as the water flow would be seepage instead of flow. Breaking the pipes throughout the field wouldn't create sinkholes, because there would no longer be continuous flow- just a bunch of random chunks of pipe, I'm hoping. But that's in the future, if/when I had a Yeoman style plow or at least a single subsoiler shank.
It's 48 acres, so I don't know that I can build up very quickly with added soil or wood chips. And it's good soil, not too much clay, but I think because of the high fertility in the PNW, we get a thin layer of dust/sediment and pollen on top of the soil that acts like a thin clay layer. Hoping that pointy hooves can help to break this up, along with seeding daikon and deep rooted grasses to filter and infiltrate the water deeper into the soil.
Most likely the tile pipe was put in to drain that swampy area in the first place.
Crushing the pipe is the easiest method to stop the loss of sol and you can then layout a swale and berm system to slow water and let it infiltrate.
In that swampy area you will probably need to build it up and one of the ways to do that is to use straw and hay laid down as if it were a mulch.
The water will saturate the straw and hay which will then decompose (not unlike a peat bog) and eventually you would end up with a raised area. (this isn't the best choice usually but it can work)
If you lay out your swale and berm system so that the high point of the swales are at the swampy area, the water will drain away from there and soak in where it is needed more, this will result in the swampy area drying out over a period of time.