I'm in year two of creating my forest garden on about 2 acres in NE Oklahoma. My lot is on (typical for this area) over grazed pasture on shallow limestone. So we have a few inches to a few feet (less than two) of pretty dense black-clay soil on anywhere from a few feet to a few inches of porous gray limestone. That is, once the water percolates through the clay it drains well, septic fields don't have a problem in this area. Challenging environment for agriculture though. My secret weapon is the fact that our local green dump gives free truckloads of shredded mulch. I plan to copiously dump this stuff on my property and since we're just getting started, till (usually a no no, I know) lots of organic matter into the clay dirt. The tilling is a one time operation to try to augment the soil with enough organic matter that I can make decent use of a swale with a hegelkugel hill on the downhill side. The thought is, if I get enough organic matter into the soil it will absorb and retain water better without having to just bury the entire clay mess.
Anyway, this brings me to my main question. Mosquito fish and other minnow-sized larvae eaters are native to this area, and naturally with swales come breeding opportunities for pest species like mosquitoes. So, I'm planning to run my swale through a natural low point and make it into a natural pool-type pond. That is I'll be pumping water uphill a few feet into a large gravel bed to simulate a river system and about 80% of the surface area will be moving through a gravel substrate that allows me to grow aquatic plants to keep the nitrogen levels reasonable in the pool. A natural filter if you will.
My hope is that during heavy rains the swale will fill and as the water stands filtering into the soil the mosquito fish and other native species will be able to run into the swale channel and have an insect buffet for a few days before the swale drys and the water forces them back into their little pond.
1.) Does this sound like it will work?
2.) What's the legality of taking natural species to stock a pond. Morally, I think I've got the high ground. I'm preserving species native to the area that may be threatened in their natural habitat. But law doesn't not always point in the direction of greater good.
3.) Has anyone actually kept North American native species in freshwater aquariums or anything for long enough to know what kinds of things I should expect?
4.) One concern of mine is proper overflow. I plan to put it in the pond somehow and I think what I'll do is have a large-ish high area filled with gravel (french drain concept) but under this will open to a drainpipe. The idea is to prevent the poor little critters from getting sucked into the drain and swept out into the lawn.
I am working on bare red clay, so I sympathize. If your free mulch is like the free mulch I get, it is closer to wood chips. You might want to be careful about mixing that into your soil, it could lock up any otherwise available nitrogen for a couple of years as the wood decomposes. I've been trying to add pond soil over the top of our clay, and then adding the free mulch/wood chips over the top of that, but if I didn't have an existing pond on our property I think I would try to just plant directly into the clay.
The nitrogen issue is one that I've considered for awhile. Would monthly nitrogen fertilizer supplement for the first year or so aide with the breakdown enough to matter? I know it's not the permie way strictly speaking, but the goal is to re-engineer the land and I'd rather take the quickest way to the right track then wait on mother nature to do ALL of the heavy lifting (though I still love her).
Other than the larger species of trees and native shrubs I had also planned to introduce a clover/nitrogen fixing cover crop to the areas that will be shaded in 5 years or so. Native-based clover and wildflower meadow crops would live in most places for a few years until the trees grew to eventually shade them out. It's my understanding that in the beginning these typically are benefited by low nitrogen soils because it starves out a good deal of competition while they're establishing. In the long run they'll be shaded out mostly and replaced with shade tolerant species on the long-term plan list.
I think that if you walk on the mulch it will sink into the soil enough it will sink into the soil at a good enough rate. I think that adding water nutrients via mulch but removing the trace mineral, boron, magnesium, etc via the soil microbes will be a overall negative for your site in the 3yr short term. And really will not make a big difference in the long term vs doing it the usual 1.5 inch of mulch over the entire 2 acres per year.
Iterations are fine, we don't have to be perfect
Companion Planting Guide by World Permaculture Association