I would like to raise cattail and have pigs harvest them. For that I need a means to drain the area so pigs can go to work.
I can grow cattails from seeds or roots and replant when pigs are done. Area above water can be replanted with cover crop geese will eat.
Ponds refill after pigs leave
In winter I can start aquaponic tilapia fingerlings
I can also hatch out goslings and ducks
Ponds should be full by summer when water warm enough to tilapia.
Goslings grass banks of pond and ducks and geese crap in pond feeding tilapia.
Cattail seeds harvested and seedlings started for transplanting.
When too cold for tilapia they are harvested. Geese are also harvested at end of season.
Pond drained and best cattails selected for plant breeding
Bring in pigs to eat cattails.
It all sounds good if the pigs like cattails and if their actions don't make the pond leak. Running pigs will pretty much guarantee that many other plants will not do well. The water may become far too nutrient rich.
It can be done. Similar things are done for irrigation and wildlife habitat all the time. Your paddy will have cat tails instead of rice.
Where are you going to put the water? do you have another use for it or do you just expect to flush it downstream? That might create problems, depending on the size of the pond.
If you have a place to recapture the water and nutrient, it sounds like it has possibilities--although just growing annual and perennial crops and rotational grazing the pigs sounds easier--what makes cat tails so special?
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You are likely right it is probably more of a problem than it is worth.
Cattails just seem like a nice source of carbohydrates if the water is clean enough.
There are some areas were only cattails grow.
It might make more sense to use sterile grass crap to clear cattails.
I can raise sun chooks, hog nuts, ground nuts, etc. for pigs to rootup elsewhere.
If the pond is large enough it may be practicle to use planting rafts to grow plant that would take nutrients away from cattails.
I have seen some nice greens, peppers, and determinate tomatoes growing on floating beds overseas.
There are alot of vernal pools in my area. Some are overgrown with cattails do to nitrogen in runoff.
It just seems like if the cattails were safe to eat and the area dry enough, pigs could plow the area clean of cattails.
When it is dry the frogs, salamandars, etc. are back in the woods again.
If ponds get low in the summer exposing cattails pigs should be able to feed on them.
If the pond water can drop a bit pig can be sure to get cattails.
I am going to guess you are barking up the wrong tree on this idea. I grew up irrigating out of reservoirs that we often ran the level up and down in. So I do have experience with that. But other experiences are probably more important here.
Clear back in jr high we had a corner of a field that we couldn't get dried up. Even if we plowed and disked and leveled it by mid way through the summer it was a cattail bog again. So my father had us fence it with electric fence and we put about 100 head of feeder hogs on it.(they had ground grain in a feeder here too so they were not just eating cattails) The area fenced was probably about 3 to 5 acres in size. Inside of about 2 days there was more mud than cattails showing and inside a week there were only a few stalks of cat tail left in what had been cattails 6 feet high. Inside a month the ground was dry and mostly staying dry except when irrigated. The hogs were held there a couple of years. It took nearly 25 years for that patch to reestablish itself afterward. For the first decade or so the patch didn't even get boggy. The hogs had completely changed the character of the dirt in the time they were there.
The second goes back to a reservoir from my post college years. The cat tails were taking it over. I tried pulling them and mostly they regrew before the next year was out. This was cat tails some of which were growing in water 3 and 4 feet deep. Then by accident being lazy I learned something. I could keep the deep water cat tails from reestablishing quickly if I chopped them off right next to the bottom instead of pulling them. If I pulled them they could be back by the next year but if I cut them off it took 3 or 4 years to regrow. Best guess is that the deep water roots were not getting enough light to regrow naturally and they were using so much energy the plants too longer to reestablish because the only energy source was the shallow water cat tails. It also meant the water stayed muddier so the light didn't get as deep. I think also the existing roots kept the healthy plants from suckering out as fast too.
The third lesson is trying to transplant cattails. We had built a new reservoir and wanted a filter strip going in to it to keep the mud from the canal from settling out in it. We seeded the area with probably 50 or 100 cattail heads each fall and tried transplanting plants besides. It took about 4 or 5 years to get the cattails really established and healthy. A transplanted cattail just barely grows the plant the first year and by the second puts up one or 2 plants from suckers. It isn't till the 3rd year it really begins to spread. Germination from seed was really poor. It seems only to happen right near the water line and it takes a lot of seed to get a few plants. This slow regrowth without established roots is why I suspect hogs won't work the way you want them to here.
Given those things in combination is why I am guessing this yours is the wrong answer. If I were going to harvest cattails for pig food I would get one of the gas powered sickle bar aquatic weed removal outfits and then I would go harvest narrow strips of cattail so the roots had lots of growing growth to support regrowth. I would float these strips as bundles over to the side of the reservior where the pigs could get to it to eat and just do that daily or ever few days.
If you try let us know as I would love to find out I am wrong. Now there are other reason to have a drainable pond. Fish and crayfish harvesting would be on that list. Simply drain the water away and catch the stuff as the water comes out the pipe. Irrigation supply is another reason.