Mulch+Trench=better water infiltration.

this attempt was started when I was trying to devise a way to increase water retention through mulching and had many failures while conducting experiments either because the water would wash away while watering the surface or would dry up to quickly, so what I did is I used some concepts from Sepp and Brad lancaster.
To illustrate, I dug a bowl shaped depression in the ground filled it with mulch and observed that I had achieved some positive results, so I then extended this into a mulch filled trench that only needed watering at 6-7 day intervals.
So what I have made is a water retaining trench that forces water infiltration,attracts worms and many other critters that eat up the mulch.
Also this is set on a zone 7 desert garden dependent on my ability to harvest rain water from our roof.
I have also provided a sketch design to show you what I mean.

I'm beginning to think along similar lines, with already planted fruit trees and other permanent plants, currently under drip irrigation. The soil is such a tight clay that after running the irrigation for a few hours the water starts to plume sideways along the topsoil and not stay near the plant. Suspicion led me to drill into the soil with a long drill bit near the emitters and sure enough, only 6-8 inches down the soil was bone dry, even after several hours dripping! So now I have a 2 1/2 inch diameter auger on my heavy electric drill and I'm slowly (back permitting) making a couple of deep holes around each tree, directly under the emitters, and filling these with something durable and fluffy....wood chips at least, or hair, or fabric scraps, etc.....something to keep the hole from caving in. The emitter will gradially fill these holes and water can infiltrate much deeper than before. Later I realized that Brad Lancaster and others describe a similar idea, called "vertical mulching"......

You can use a hose to "drill" holes like you describe. Just point it into the soil.

I read about this hose idea on another thread on here and went right out and tried it. It went through the first few inches of relatively loose topsoil okay, but once it hit the hard dry clay beneath, no way! I think it might work but I would have had to do just like I do with the auger....fill the hole with water, let soak in (which can take two days), drill a few inches, remove the loose soil, and repeat.

In reply to Alder burns comments. At first I thought compacting the bowl depression would hold water longer but found this did not work so well, as far as compacted clay goes I read that to de-compact hard pan was to do a double dig where you loosen the top soil then work on the hard pan with a pick ax or depending on the size, a backhoe.
the winter squash I am using to test this with has so far spread far into the garden and has fruited several hubards so far, another thing Im doing is pouring green manure tea into this trench and am observing closely during this test.

Alder Burns wrote:I'm beginning to think along similar lines, with already planted fruit trees and other permanent plants, currently under drip irrigation. The soil is such a tight clay that after running the irrigation for a few hours the water starts to plume sideways along the topsoil and not stay near the plant. Suspicion led me to drill into the soil with a long drill bit near the emitters and sure enough, only 6-8 inches down the soil was bone dry, even after several hours dripping! So now I have a 2 1/2 inch diameter auger on my heavy electric drill and I'm slowly (back permitting) making a couple of deep holes around each tree, directly under the emitters, and filling these with something durable and fluffy....wood chips at least, or hair, or fabric scraps, etc.....something to keep the hole from caving in. The emitter will gradially fill these holes and water can infiltrate much deeper than before. Later I realized that Brad Lancaster and others describe a similar idea, called "vertical mulching"......

can your clay be compared to a block of forming clay as far as tight goes?

I would think it might be comparable. Adobe was a popular building material during colonial times in this area. There is a significant amount of rocks, which interfere with both the hose and auger methods.... I do know that in most places in the yard, a hole dug down into the subsoil (say a foot deep or so) can often take two days to soak in when filled with water, which is a sign that the clay is tight enough to cause drainage issues with sensitive plants.....in this light, I planted the most sensitive plants (pistachios, pomegranate, apricot, nectarine, citrus) on raised mounds. I think I need to do this with the figs and persimmons too as these seem to be languishing.....

Reminds me I should do some swales in my garden. Laden with mulch they will help retain moisture in my excessively drained sand.
Curious how the same technique can be beneficial in conditions at opposite ends of the spectrum.

Peter Ellis wrote:Reminds me I should do some swales in my garden. Laden with mulch they will help retain moisture in my excessively drained sand.
Curious how the same technique can be beneficial in conditions at opposite ends of the spectrum.

Its kinda like a cross of swale and infiltration basin since there's no slope in the garden. the first time I did this successfully there have been worms eating up the mulch and making handfulls of fine grity soluble matter for the plants so take up.