Ebb and flow irrigation ponds.

I want to create a bunch of 4" deep ponds. How do I make a pond that is even in depth? (within half an inch.)

Background: I grow willows in containers for reclamation. Up to now I've watered with sprinklers, but in a hot spell, watering them fast enough without creating moldy leaves is a problem.

I figure with a series of ponds, I can flood one, leave it for a couple hours, then pump the water to the next pond, top it off, and so on down the series.



Starting from lumpy pasture, what is the easiest way to do this?

At present my idea is this:

* Rototill a patch bigger than the pond by about 2 feet each way.
* Put in my frame sinking the bottom edge a couple inches.
* Verify that the frame top is level.
* Make a hanging screed to level the bottom of the pond. Move extra dirt out as needed.
* Now I have an unconsolidated bottom. Rent a plate tamper and pack the bottom. This will take the bottom down another inch or so.
* Add some of the fill back, rescreed, and repack.
* Repeat until I have a flat, firm bottom.
* Line with 15 mil UV resistant plastic, stapling to the upper edge of the frame.

This sounds an awful lot like work. I will need somewhere between 10 and 40 of these ponds eventually.

Thoughts:

Why not just a bigger pond?

Different stages of willows require a different frequency of watering. When small they may only need to be watered once every two weeks. When larger, every three days.

A 4-5 foot wide pond makes it easy to move plants without wading. 30-40 feet long with aisles at either end means only a 15-20 foot walk from the trailer.

This width also reduces the amount of dirt to be moved for terracing. (The area is on about a 3% slope.)

We have no precipitation in Ladakh to speak of, so we water everything by either running canals alongside (trees) or for the garden, by making square or rectangular garden beds in a grid divided by simple raised dividers about 3 or 4 inches tall. Those are made very simply, much simpler than what you envision. In spring when preparing beds we add manure on top, then plough, and level the beds and form the sides with a tool like a hoe but wider and blunt. Then during the first watering you might stand around with your hoe-thingy raking some soil from high and dry patches into the low patches or raising the sides further. Dead simple. But this is for planting in the ground, not for soaking containers and then draining. Most of the beds we just flood once each time and then block it off and let it soak in, but some of them do overflow to the next lower section.

Another possibility since you seem to be able to invest in the project, would be drip irrigation. You could line up all the containers that are of a similar water-need in the same lines so you could water each group separately without splattering the leaves.

I wonder why you are planting willows in containers, when they are so easy to plant by cuttings stuck into the ground in the final location. I expect you have a good reason, such as being unable to water them after planting out into their final locations?

Hi Rebecca You have good points.

While willows propagate readily, they do not compete with weeds and grasses. When using them for reclamation/habitat enhancement, the clients want them about 1.5 times the height of the local weed population. I also sell these for shelterbelt use. 2-3 feet makes them easier to miss with the mower.

While willows are commonly thought of as wetland plants, many of them do well on upland sites once established. The larger size and established root system gets them off to a running start.

I live in a borderland dry ecology. We get about 16" to 20" of rain a year. Water is one of the limiting factors. My current supply is 5 gallons per minute. This is adequate, but becomes marginal at present when temperatures exceed 30 C (88 F) I currently have 16000 trees.

Our winters are very cold. Pots that are isolated by themselves change temperature too fast -- faster than the roots can adapt. By clustering pots close together I only lose a few percent. If spread out, I lose 50%. Setting up drip irrigation for clustered pots is a pain It remains a pain for selecting trees for clients, for weeding, for checking that drippers are working.

I use drip irrigation with my larger pots. Works well for 5 gallon and up. But I need to check drippers every 2 weeks. A block of 300 trees takes about an hour to check. Pots that are spread out also have more weeds. (more sunlight reaches to soil) and the south side of the pot heats up more.

A #1 pot is 5.5" across and 7" high, and holds 3 liters of soil. To get a #1 pot to 2.5 feet makes it unstable -- easy to knock over. So some sort of frame to keep them upright is an advantage. At present I can't water fast enough for #1 pots. If I sprinkle that often, the leaves are wet too often and I get problems with fungi.

You have given me an idea however. Flooding the dirt pen is an easy way to verify that the bottom is flat and level.

When people plant willows in this region, we plant them with about 5 or 6 feet above ground and 1.5 feet below. Would that size still not compete with weeds? Or is it a problem around the roots?

Are you selling these to clients? In which case containerized plants are more attractive?

Lots of, perhaps most trees that are grown in one place and then transplanted to their final site are grown in the ground and then dug out. Would that work with willows? Or would it be unacceptable for the clients?

No. A willow here won't have enough water in the stem to supply the leaves while roots form. Indeed, when I'm rooting cuttings, I have only 1 or 2 buds above ground on a 10" cutting.

With slower rooting cuttings, I place them initially in the shade, or start them in cold aerated water until I see the white specks that are primordial roots start to form. The latter gets tricky, as in a day you can have bumps instead of specks. And those rub off when you stick the cutting. Which means predrilling an oversize hole, and hoping that you can pack it well enough after.

I suspect that our soil temperatures in spring are too cold for fast rooting. (One of the reasons to use above ground pots)

Regardless of what is possible, my customers want 1 to 3 liter root system on willows, poplars, alders, dogwoods, all of which tolerate episodic flooding.

Even drip irrigation uses more water than ebb and flood. In drip, you have to have some water pass through the pot. In addition, to be efficient, a drip system has to have a plant under each dripper. As trees come and go erratically during the summer, at any given time up to 30% of my drippers are dripping onto tarps or watering weeds.

Remember that whatever I do, I have to do it a minimum of 500 times, and possibly 5000 times.

E.g. Fertilizing each pot: I have a gadget that when I operate it (much like a shotgun loading a shell) it drops 1/2 tablespoon of fertilizer -- about right for a 2 gallon pot. I can do 20 trees a minute. But 10,000 trees is still 500 minutes -- over a full day. And in effect two full days given the daily routine.

Seconds count. If I can spend 50 hours in late fall or early spring that saves me a day during my busy season, that's a win.

Sprinklers are erratic. Even running them with 150% overlap I get dry spots on the edge of the zone. Drippers vary about 20% within each batch, and the ones at the far end of the line never drip as much as the first ones. (I try to run my zones down hill to compensate for this at least in part.) If I can get even depth ponds, this should be close to uniform.

Hi SG,
welcome to permies,

at first I read 4 ft rather than 4 inches!!! and said what is this guy crazy

building a swale on contour 4 inches deep and lining it with plastic would be a good automatic way to water the plants
by putting the swale on contour (rather than straight lines) levels the bottom
putting the hose into the swale then fills it evenly
bottom watering will encourage roots to go down and avoid getting the leaves wet
instead of pumping, maybe design the swale with a standpipe and drain
to move the water to the next lower swale, pull the standpipe after the plants have soaked enough
your fertilizer could also be added to the water as you fill the swale

just some things to think about

https://permies.com/forums/f-90/earthworks

swales


BTW where are you located?

I'm located near Edmonton Alberta.

A swale is basically a shallow ditch, right?

How do you get the necessary precision? It has to be 4" deep. Not 3.5" in one place and 6" someplace else. It has to be on contour. Not 1" lower 100 feet further along. This is why I was considering separate blocks. I can get a foundation form level within a quarter inch.