I live in a desert, which gets almost no rain in the warmer six months of the year. Terrifically, we got rain today! (It’s been something like three months since the last one. This is normal for my climate.) We got nearly a half hour of moderate rain, which is a wonderful gift at this time of year.
I went out tonight and was looking at my beds that are deep mulched in wood chips. The top inch of wood chips was soaked, but when I pulled it back, I saw everything underneath was bone dry.
I’m thinking this means deep mulch is probably hydrophobic to receiving rain. Great for keeping water in the soil if you don’t expect to have any at all, but lousy for taking advantage of any rain you might get.
So that gets me thinking about something new I could try next year. What do you guys think of this?
Remove the top inch of dirt.
Plant any seeds that can germinate really deep down in the soil.
Add several inches of wood chips.
Put the top inch of dirt back on top.
I’m thinking maybe a dust mulch on top of a deep wood chip mulch would be way better at receiving rain, and just as effective at keeping the moisture in.
That would do nothing good atleast. Soil would just go trough woodchips at some point. I don’t think in your climate it or anywhere where it gets really dry those short moderate rains are gonna make any difference as anything that is bone dry on the top is going to soak it up and then evaporate in the sun before it gets too far. Not sure if some other material like hay would be any better. Does make me wonder if mulch does anything in no to little rain enviroment except weed control.
If you put drip irrigation under the mulch, which is what I did last year, mulch makes a HUGE difference.
This year, I still have the drip irrigation set up, but I made a mistake with my rain tanks, and didn’t lift them up high enough for them to have any water pressure when I run a hose from them. So I’ll have to wait until they’re empty, then get some cement blocks to lift them up a foot or two. Next year, hopefully, I’ll be able to run drip irrigation from them, which is soooooooooooo much easier and more water efficient than filling a watering can and carrying it back and forth.
Hmm. Well, the berms are currently bare dirt, because I don’t have enough mulch for both them and the swales. Maybe the berms collected a bunch of the rainwater, which will seep down into the soil of the swales? If that happens, it might be an argument for leaving berms unmulched in a desert garden!
I’ve found that if you water them enough so that there is water that makes it down to the plants it is more even, but you still need to get the right amount of water to the plants. I do like doing drip irrigation like you’re saying because it just gets the areas you need. But ya, I tried doing back to eden and it doesn’t work here without watering
Definetely helps if there is any signicant amount of watering/rain. I was just thinking it in the context of likely not getting any rain. One thing that came to mind is that are you sure nothing got through? With no dig ground should soak up water really fast. Maybe you could trial what happens if you water lightly from the top. Then check right after and bit later to see if it stays. Problem might be that your rain wasn’t heavy enough to make difference. It might rain half an hour but actual amount of water is negligible. Light rain for half an hour might be 2-3mm which is 2-3 litres per m2. It’s more like heavy mist in terms of water in the ground level.
What would be the minimum thickness of wood chip that would maintain soil moisture? Perhaps that could be optimised. But of course, no matter how thin/thick the mulch there will always be a rainfall amount below which no water gets to the soil.
If you get half an inch of rain, of course nothing will get through 4 inches of woodchips. Check where you have bare soil and see how deep the water penetrated. I’m guessing not much more.
It’s not that the woodchips are hydrophobic, they’re just dry enough to absorb everything they’re given.
I don’t have any experience with drip irrigation so, sorry if my question is foolish. But my question is this: If the usual way is for that system to go drip drip drip gradually, I wonder how it would compare to using the same total amount of water, but flooding it out all in one once a week, instead of gradual? I’m wondering this because I wonder if that way, it would encourage the roots to go deeper, making the plants more resilient. And so if that combined with the mulch might make for better results in your dry climate?
I’ve heard and found that in desert climates deep mulch can be counter-productive, unless combined with soaker or drip irrigation. Two ideas: moveable mulch which can be raked away when a rainy spell comes and then raked back, and rock mulch. Native peoples in several different desert areas used rock mulch, which will retain water in the soil but does not soak it up. They also maximize the benefit of light rains by channeling them into smaller spaces. The problem is how to practically manage a rock-mulched garden; I’ve never heard of a good way to do it.
There are a number of reasons why drip irrigation is counter-productive. Plants need to dig deep and chase the water down, not just spread out in the top few inches of soil.
I have done dry gardening for years, under deep mulch, and I have never found the mulch to be a problem.
Wow rock mulch, sounds cool! I wonder, perhaps following the traditional Native way of doing it could be ‘good’?
That’s why I was suggesting letting the system give the whole week’s worth all at once, so that the water would go down deeper, and the roots would follow.
I kind of experimented with this with my tomatoes outside also. I have little experience but anyway, rather than water every day like I see my neighbours doing with their tomatoes, I just put lots of water in the holes right before planting them, then watered them like maybe once every couple of weeks (no schedule, just when I felt like it, and with a hose that is so short I have to hold by thumb on it to spray the whole plot from one single position), and even then, not very much. I even thought I was spoiling them by doing that much, until I realised others were watering every day! It has been really quite dry and hot here, compared to how it used to be. (I’m also growing rice like this - we will see if the results are any good, rice is meant to be challenging here anyway, let alone growing lowland rice in a neglectful upland method!)
My intention was the same, make them put out deep roots and be less dependent on me. I watered them sometimes because this year I’m doing lots of crosses. I hope to have the F2 seeds ready for next year, growing F1 indoors. And I am considering at least one plot or maybe most of my space, next year for F2, no watering at all. Since my intention is to breed delicious neglectable tomatoes. I think it would be nice to never have to water them, except for at the moment of planting them. Maybe even never, if they could be seeded straight into the soil, though I would think I should select for that later on.
I’ve tried rock mulch a few times. The rocks sink into the soil within about two months. You can either keep digging rocks out and putting them back on top, a huge amount of extra labor, or you can keep adding more rocks on top, thereby making the soil rockier and rockier and thus significantly less pleasant to work in. I also suspect soil that is more rocks than soil is inhospitable to roots, but I’m not sure if I’m right about that. It’s just a theory.
Organic mulches sink into the soil as well, of course, but that’s actively beneficial because they become rich hummus that makes the soil better.
A rock mulch on top of several thick sheets of cardboard might work. If there’s a barrier, they won’t sink into the soil. The cardboard would also keep down the bindweed (bindweed will grow through rock mulch). Of course, you’d have to remove the rocks entirely to replace the cardboard barrier once a year (because it would rot away), but it might be a good combination.
Ahhh, of course. I forgot that inches of rain is a measurement of how deep the water will penetrate into the soil (or mulch). You’re right, we probably did get about half an inch of rain.
You’re right, of course. They’re not hydrophobic; quite the reverse. They’re sponges. That’s great when they’re deep in the soil because they’ll release the water when the soil is dry. It’s less great when they absorb all the rain and then it all evaporates before any of it reaches the soil.
Don’t forget windbreaks. Planting windbreaks such as rows of trees or shrubs along field boundaries helps reduce wind velocity, which can lead to less evaporation and better protection of crops from wind damage. If you don’t have windbreaks you can plant then you could try physical windbreaks other than plants.
You already know that incorporating organic matter, compost, or other soil amendments can enhance soil structure, water-holding capacity, and nutrient availability. This is what the wood chips would do in the long term given enough moisture.
Crop spacing. By increasing the space in-between individual plants you allow more water over a given measure of ground to be available to the plants you want to grow. This is why you must also be very diligent about weeding dry land gardens which is why most people resort to mulches.
Earth works methods such as contour farming, terracing, and furrow diking and swales help capture and retain rainwater, allowing it to infiltrate the soil and reduce runoff.
You know, I’m starting to think the answer is to do the reverse: plant everything way more closely, so that the soil stays totally shaded.
I have potatoes growing in full shade under an apple tree that look happy right now. Potatoes. And I’ve watered them only twice in six months. All the rest of my potatoes look miserable, and I’ve given them ten times more water.
I’m starting to wonder if David the Good’s grocery row gardening system would be an extremely good idea in a desert.
Especially when I watch a video like this:
That guy consistently has fantastic advice about growing in a desert, and that particular video really made me sit up and take notice.
If you are not using mulch, then that may work provided you can provide enough water for the plants. The mulch would shade all the ground against sunlight.
Hmmm, come to think of it, maybe I should consider growing some trees in pots. Presumably drought tolerant ones that aren’t quite hardy to my zone, so their being in pots would be valuable in order to carry them indoors for the winter. Carob and moringa may be good options to try, for instance. The pots would automatically make them provide more shade, which may be a good thing.
I’ve tried pots before and found that they dry out way too quickly, and are thus a terrible idea in my climate.
But if they’re sitting in a garden bed, any excess moisture that drained out would go towards other plants I care about. So maybe it would be worth it.
When I tour gardens, one of the most common points of failure that I observe involves people putting wood chips INTO their soil. Therefore, I think that putting an inch of soil over wood chips would tend towards creating nitrogen deficiency.
