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dan long
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I will post this on "greening the desert" and "gardening basics" since i don't really know where this belongs (perhaps one of the moderators would like to help me out on this one?"

Steve Solomon breifly covered this subject in a book i read, "growing vegetables west of the Cascades". There is a long e-book that goes into a lt more detail here: http://homesteadbasics.com/wp-content/uploads/2009/12/8300483-gardening-without-irrigation-dry-farming.pdf

What he says is that by giving plants lots of elbow room, some kinds become much more drought resistant. That's because they don't compete with each other for subsoil moisture. He also states that plants will become larger and less prone to bolting. He even says that yeilds from this type of garden are comparable to intensivly planted gardens (so long as they are regularly weeded).

Quick summary: during rainy times, the soil will get charged to "field maximum". During hot, dry, windy season the soil acts as a moisture bank to be drawn from. Bare soil doesn't lose a significant ammount of moisture anywhere below the top few inches. That's because the top inch, once desiccated of water doesn't allow water *up through it* (i forgot what the word is). Soil only loses moisture when sun wind and heat draw it from the leaves of plants. Therfore, giving plants lots of elbow room makes them able to withstand drought (certain water loving plants not included).

What is the permaculture rebuttal to this? He just recommended leaving the soil largely bare. No cover crops, no mulch, no soil covering polycultures. Although, he never mentioned the possibility of using succulent, waxy leaved plants as living mulch.

On that subject, would a sunken hugelculture bed or a keyhole garden be able to support an intensively planted polyculture garden with zero irrigation all throughout a dry season in say zone 8? What about a really hot zone like zone 2 or 3? What about desert areas?
 
Jordan Lowery
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i dry farm all kinds of things here in the foothills of California. even with the worst rain year in recorded history im still dry farming permaculture foods. I learned a lot from that book but do not follow most of it.

i have mulch grown on spot and find this critical, its loose and about 4 inches thick, made from many many different plants. its also high density polyculture, well over 200 per 50x50' and diversified root layers.

when the top couple inches of soil dries out the moisture below is "capped" down in the soil like you said, and also like said the plants transpiration is the only way for moisture to leave the soil. that said choosing the right plants will reduce this.

swales, terraces and hugels placed in the right spots can add to the length of time you can dry farm.

its really fun, easy and the quality of food is outrageous. dry farmed tomatoes are out of this world.
 
Burra Maluca
Mother Tree
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dan long wrote:I will post this on "greening the desert" and "gardening basics" since i don't really know where this belongs (perhaps one of the moderators would like to help me out on this one?"



I've got rid of one of the posts and made this one show up in both forums so that all the replies will be in the same thread. If you think a post needs to be in more than one forum, put it in one then hit the 'report' button and ask a moderator to add the post to another forum. It's much better than having lots of threads about the same thing with all the replies scattered all over the place.
 
William James
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I have heard roto-tilling in massive amounts of woodchip produces a no-irrigation garden.

Problems I see with that:
1. fungus buildup
2. nitrogen deficiency.
3. Requires a very cheap source of wood chips.

Supposedly the person advocating it said that there is a nitrogen dip and then things get stabilized. Don't know about the fungal build up. I would also be interested in his soil type.

Hugelculture supposedly helps, but I still have water-stressed plants on top of my own, so I can't vouch for that technique 100%... I must be doing it wrong.

Personally I don't follow the "space the plants" method. I had 4 months of no rain. The plants just seem grow very slow but for the most part they stay alive if they are planted tightly.

The "permaculture response" is that yes, spacing plants make it possible to reduce water needs -- but it also provides niches for other, aggressive and plants who can fair much better than your hybrid tomato plant (who is, generally, a wimp). So permaculture design would have you evaluate how much you want to weed, maybe more here and less there, and space accordingly. It's not an either-or.

The other potential responses/factors: diversity of root structures, diversity of plant functions, diversity of annuals/perennials/cultivated wild plants, diversity of time when each plant is drawing the most from the ground, tap-rooted plants that bring up moisture, microclimate: the effect of shade and reducing wind effects on the soil surface, reducing wind and dryness around the leaf (more wind and less humidity on leaf means more transpiration).

And then I run out of ideas...
edit: compost can be used as a mulch, especially in dry weather.
William
 
dan long
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Thank you Burra Maluka. I will do just that in the future.
 
James Colbert
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If the wind speed is slow because of windbreaks, and sheltered micro-climates water transpired by plants is not carried off in the wind. The area remains more humid reducing transpiration and water is conserved in the form of morning dew.
 
William James
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Just to harp on the point of Taproots and Diversity of plantings, a tree (n-fixing, biomass producing) would be, in my opinion, a good addition to a no-till vegetable bed. A tree is a 75% water column coming directly out of deep subsoil. You have to think that it would be willing to share some of its water via mycelium to the surrounding vegetables.

I currently am using Wisteria and comfrey as a paired planting to increase minerals and water in the topsoil.

This coming year is the first real test. Last year it was just getting established.

Oh, and I just blazed through
gardening-without-irrigation-dry-farming.pdf

And I thought the information was really good. I have some reservations about tilling and hoeing, bare soil, double-digging and aggressively weeding in general, but he's the expert. I noticed most of the things he had to say about heavy clay soil (which I have) was negative, and I suppose he's right.

And it was encouraging his advice to trial everything and see what works.
William
 
Miles Flansburg
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I have been trying to squeeze in reading paul stamets book, "Mycelium Running". I have only skimmed through it so far but he does a lot of work with wood chips and fungi. He also talks about the mycelium being a water transport system.
 
William James
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One interesting thing the book talks about is the difficulty of adding organic matter. The reasoning is there is a limit to what you can do, simply because the more organic material you add, the more biological activity happens, which means you need more organic material to keep the fires stoked, so to speak.

While I agree with that analysis, I think that when the organic material is high, when more biological activity is happening, when you supposedly need more organic material, that might be the time that adding woody material to the mix might extend your organic matter in time, the same could be said for biochar. Wood increases fungi, biochar bacteria.

I have a feeling the book wasn't contemplating adding wood or biochar to soil. Both can help with water retention.

William
 
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