Desert market garden

I've discussed in past posts that there is a lot of vacant land near Denver that could be used for urban farms, but most of it does not have water access and getting water installed is prohibitively expensive. With only 15 inches of rain a year, there is a very limited range of vegetable crops that can be grown without irrigation.

What if a farm was laid out in alternate rows on contour 8 feet wide, and every other row was a plastic covered low tunnel. However, the plants would not be growing in the low tunnels, but in the open rows. On the long sides of the tunnels the plastic would be buried in the bottom of shallow mulched trenches.

This would give the uncovered plots the equivalent of 30 inches of rainfall. Furthermore, light rains that would have merely evaporated off open ground would be concentrated into the trenches and sink into the soil, thus boosting efficiency of water usage.

Would this set-up work to grow standard vegetable crops? (Combined, of course, with mulching, varietal choice, etc.)

Gilbert Fritz wrote:I've discussed in past posts that there is a lot of vacant land near Denver that could be used for urban farms, but most of it does not have water access and getting water installed is prohibitively expensive. With only 15 inches of rain a year, there is a very limited range of vegetable crops that can be grown without irrigation.

What if a farm was laid out in alternate rows on contour 8 feet wide, and every other row was a plastic covered low tunnel. However, the plants would not be growing in the low tunnels, but in the open rows. On the long sides of the tunnels the plastic would be buried in the bottom of shallow mulched trenches.

This would give the uncovered plots the equivalent of 30 inches of rainfall. Furthermore, light rains that would have merely evaporated off open ground would be concentrated into the trenches and sink into the soil, thus boosting efficiency of water usage.

Would this set-up work to grow standard vegetable crops? (Combined, of course, with mulching, varietal choice, etc.)

I would recommend establishing rainwater harvesting methods (such as keyline swales along your contours) to establish a pasture-based regenerative agriculture system of production agriculture, as advocated and demonstrated by Gabe Brown. Look up his series of videos to be found on YouTube. Also, explore the videos produced by Ray Archuletta on the same subject.

Fifteen inches of precipitation is a huge amount of water! (compared to the 1/2" of water that my land in Arizona got last year (We're in a drought right now).

Think about all the input costs and embedded energy represented by all that plastic! Why not let the plants do that for you "for free"!

You only need to establish a pasture based diversity of perennial native grasses and forbs (plus specific annual plants that work to accumulate any deficiencies in your soil. Plan on, utilizing intensive livestock management to "mob-mow" each paddock (using movable electric fences to control the movements of the cattle). Their manure also adds to the feeding of the soil. If you don't want to use livestock, you can use a special non-compacting roller to knock down the perennial grasses (without killing the plants) so your cash crop can be harvested. It's a bit difficult at first to understand how this method can work because it is 180 degrees different than the "traditional" methods that have ruined so much soil around the world. Use the plants to provide you fertilizers, and to provide habitat for the natural predators of insect pests, and to provide all of the necessary nutrients required by your cash crop.

It will take perhaps a couple of growing seasons to establish your base pasture, in which you will be planting your annual cash crops. Once you've established your native grass pasture, you use no-till methods to plant your cash crops directly into the existing pasture consisting of a diversity of perennial native grasses: the more diversity, the better. You can prep your paddock for planting your cash crop by planting a combination of nitrogen fixers (legumes, clovers, and vetches) and nitrogen accumulators (such as dikon radishes) along the rows where you will later plant your cash crop. Gabe Brown and Ray Archuletta describe how this is done in their videos.
I have listed many of the links elsewhere in the "Greening the Desert" forum. You will want to conduct soil tests using the Haney soil test to determine exactly what your soil needs, in terms of specialized accumulators for other nutrients, such as potassium and phosphorus. The key is ALL the nutrients that your cash crops need can be gotten using plants.

Will they allow that kind of water harvesting near Denver? We go to Denver fairly frequently and there is certainly open land. I just imagine it would cost a small fortune to purchase any of it. I like the idea though, quite a lot. The trenches would also help capture snow, which is a lot of our precipitation.

I like this post, I'm VERY interested in dryfarming...  Where I'm from in Oregon, my primary need was to stay dry and get as good drainage as possible  -both for plants and one's own body!   Now I'm in the SW, and it's been so exciting learning about how to retain water and use as little irrigation as possible.  It's a mental switch when you come from the land of mud.

I think I understand the method you are describing, and how it would collect water, but I believe it will still require more traditional earthworks to be successful.  I explain why I think this at the end of what I wrote here... in case you just want to skip to that point it's the last couple paragraphs.

First, here are some factors that will effect whether you can grow market crops on that land with minimal or no irrigation.  The timing of your rainfall, the soil's water holding capacity and fertility/humus content, for example.  

Some questions to ponder:

How much topsoil do you have?  Dryfarming requires a lot of topsoil... plants need to develop deep roots for it to work.
How much rainfall happens each month?  Is there enough to support plant growth in the spring through summer through fall?  You may be able to find this out from local weather history.
Does your soil have any clay in it?  What's the water retention like?  You can do a drainage test, and a simple soil-mixed-with-water test to see how much clay, sand and humus is in there.  Dry farming needs soil that holds water.
What sort of plants grow there right now?  These are your soil indicator species (aka "weeds"). Are they plants that use up nitrogen, or are they primarily nitrogen fixing plants?  

If you have land with a whole bunch of nitrogen fixers growing on it, that typically means it's low in nitrogen in my experience.  Market garden crops are mostly annuals (or biennials and short-lived perennials who are all treated as annuals) and most edible annual plants take a lot of nitrogen to get big and juicy and tender the way people tend to want them.

And all market garden plants I know of need enough water to initially establish roots... so even some dry farmers use irrigation to get plants started.  Certain crops are more suited to dryland farming, like seed crops, some herbs, and grapes.

In California, people do wine grapes.  They are tasty, too.  People sell them at farmer's markets on the west coast.  I love it when the muscat and the champagne grapes come out. I bought some Pinot Noir grapes to eat fresh this year, they were delicious.

Here is an article interviewing some dryland market farmers.  They note that dry farming in extremely sandy soil (with no clay and little humus) is not really feasible... it needs to be able to retain water.  The people growing tomatoes and potatoes don't explain this in the article, but they still have to irrigate.  To them, dryfarming means irrigating less - but to others the definition of "dryfarming" is without any supplemental irrigation once the plants are established (grapes and some orchard crops can be done like this), and to others dryland farming means with no irrigation at all (wheat, some legumes, or crops in regions with really useful rainfall patterns).  I think this is an important distinction for you.  

To Grow Sweeter Produce, California Farmers Turn Off The Water

Dryland farmers often use a technique for keeping soil moisture that is sometimes called dry mulching or dirt mulching.  This involves tilling the upper inches of the soil, making the soil into a fluffy mulch.  This serves at least two purposes - to create a capillary break and stop evaporation, and to stop the formation of a soil crust that would prevent new rainfall from permeating the ground.  One has to till again after each rainfall or irrigation for this to work.  BUT, and it's a big but, there is more to this, because dirt mulching at the wrong time (when the soil moisture is too low) will create dust, and then your topsoil blows away.  

Mulching with chips can perform the water retention, too, however, it could also lock up the nitrogen for awhile in dryland plantings and it's a bit of work to get hold of enough mulch.  Have you watched the Greening the Desert Jordan project videos?  From what I can tell, it took a few years of mulching and micro-irrigation to improve the soil to the point of supporting market crops.  Hopefully someone reads this and correct me if I am wrong.  That was my understanding form the videos I've watched.  Building soil to the point of supporting the lovely juicy stuff we like to eat, rather than just soil that will support poky legumes, takes awhile.

Here is a very useful paper on dryland farming:  Dryland Farming: Crops & Techniques for Arid Regions

Even though the authors aren't specifically talking about permaculture they say:

The first essential step in dry farming is bunding.

Lots of useful information in that paper.

This is a good rundown on the principals of what dryfarming is and what it requires, like very distant plant spacing, for example:
California Agricultural Water Stewardship Initiative - Dryland Farming Overview

That is a very informative piece of writing, with a huge resource list at the bottom.

Will Bucklin of the Bucklin Old Hill Ranch talks about his experiences learning dryfarming on his site.  He's a very good writer and it's more fun to read and less, ahem, dry than the papers above.  He has a series of blog articles on his experiences here:

Will Bucklin's Old Hill Ranch stories about becoming a dry farmer

I think you have an interesting idea... and I would like to see what would happen.  I'm experimental that way myself.  Now in my life I prefer to get away from plastic film, though.  So much gardening in the US involves plastic, and yet in other countries (like India and Africa) they do fine without plastic film.  I understand the convenience, I'm just personally interested in solutions that don't create waste to toss later.  I've done way too much of that already!  I kick myself thinking about all the plastic I relied upon because I didn't know there were other ways of doing things.  Argh!

In the end, I believe successful long-term, organic dryfarming will still require traditional permaculture-type earthworks to work really well through weather changes, even in urban areas.  They are designed to most effectively catch more water than just what's hitting the adjacent surface.  This is taking a longer view, making a bigger water recharge investment than an approach which is only collecting water on a yearly basis for the rows adjacent to it, for example. I get that you can't change other people's properties...but I think you may need to work with them in ways.

Currently I'm listening to Paul's podcasts with Geoff Lawton: Paul Wheaton and Geoff Lawton Podcast List

In one they discuss how it takes swales about 7 years to fully recharge most ground to it's holding capacity.  That was eye-opening to me and made me understand the greater goal here - it's not to get enough water in the ground so your plants can make it through a season.  Instead, we can create drought-resistant, highly resilient, water retaining, fertile land that can support plant growth indefinitely.  That's so exciting to me.

Good luck in all your endeavors!  Maybe some of the farmers from near the Rockies will be able to pipe up with their experiences.

Sounds like a cool idea, Gilbert! I'm really digging your response, too, Kim: great stuff, thank you! I would second what Kim says about getting away from plastic and doing more with earthworks. We don't have a market garden -- although that is an eventual goal -- but we currently have a large garden in southeastern AZ with an average of 13" rain/yr. (much less these last few years, as Mark notes) and NO WELL. We collect rainwater off our roof and filter it into cisterns, but most of that is for our very moderate domestic use, so here is what we do in order to work towards meeting our food needs ourselves from our land. I think this would work in a place like Denver, too:

In our winter rain and summer monsoon seasons, when they happen, water floods over the land, especially areas of heavy clay and along compacted dirt roads and driveways. We are gradually working to make the heavy clay areas on our land either hold water temporarily in small ponds or slow and filter in the water. But for the water from the roads and driveways, we divert it using canals and berms. We lead it away from the driveway and the house in about foot-deep canals, then bring it through a chickenwire fence into our first garden, where some of it continues slightly downhill along a feeder canal and some of it moves slightly downhill through a second chickenwire fence to a feeder canal in our second garden. Each garden is composed of sunken rows/beds in either a serpentine configuration or modified concentric rings, depending on the contour of the land as well as working around mesquite trees, wolfberry bushes, and other things we want to keep around. They can be quite deep, as much as 2 ft. in some places, depending mostly on grade to keep the water moving where we want it to. Those sunken rows/beds are filled deeply with mulch, with green mulch (weeds, leaf litter, chop-and-drop, etc.) first, then wood chip and small stick mulch from our wood chopping area.

Our initial efforts are focused primarily on growing staple crops like beans and squash (corn when we can). Our gardens are in sandy areas, which the beans really like, and also we eat a lot of beans, so we grow a ton of them. Mostly tepary beans (four or five kinds, aiming for a landrace), because they love our climate, but also cowpeas (three kinds, also aiming for a landrace), which do very well here, and one common bean (a stable pinto/black cross). Many different kinds of squash thrive amongst the beans, benefiting from their nitrogen fixing, and we're gradually adding in other things as well, perennial wherever possible.

When we seed beans, we use something like a pole, "dibble" a hole in the side or "bank" of the sunken row, then drop seeds in. Squash we seed in the top edges so their roots get the water from the sunken rows but the plants don't get waterlogged themselves. A very small number (two or three; possible even just one) of flooding rains in a season will sustain at least a very good tepary bean harvest and seemingly a good squash harvest as well, especially if the monsoon doesn't start too late. We didn't seed corn this year because the monsoon started too late, but we will try again next year and let y'all know. It didn't yield very well year before last, but I think it wasn't in enough of a block.

In that first garden, the feeder canal feeds one last downhill row, then that goes through a small rock dam and widens out into a sunken delta where I plant root crops so that my digging around won't mess up the careful grading of the rest of the garden. This gets fed only when the first garden overflows, but just getting flooded twice has produced radishes and turnips, gotten a clump of horseradish established, and got the garlic sprouted this first year.

We extend things out a little by feeding our limited graywater through buried drip irrigation to the second garden, especially a bed area at the top where we have herbs (even mint!), greens, cucumbers, hot peppers, tomatillos, sometimes tomatoes, etc. We also have one buried clay olla that helps support the herb bed (which is a little too far from the buried graywater dripline) and would like to do more of that in future. Another way we're hoping to extend things is to put a metal roof over an old camper we use as a shop and run its gutters into a separate cistern, then use that to drip irrigate a garden. You could do something similar even with metal on the ground if it's uphill from your planting area (or a garden shed or barn with a metal roof and gutters) and collect in whatever clean food grade containers you can find (55-gallon drums, trash cans, etc.).

We use almost entirely salvaged materials when we need something for our gardens that we can't fashion out of yucca posts, mesquite deadwood, etc. We've even found irrigation line abandoned in the desert. But plastic just does not last out here, between the UV and the winds, so we aim for steel, aluminum, etc. whenever possible, and I'd encourage the same for any southwest market garden.

I think these things would make great community projects if you could get a local neighborhood group involved. It's accessible, human-scale, and kids and people like me can see rewards for their efforts pretty quickly a lot of the time.

Beth -fantastic stuff!  Would you consider making what you wrote into a post and adding some pictures?  I would so enjoy seeing examples if you have time ever.

And ollas!  Yes!  So useful.  We made ours out of clay pots and Chemlink non-toxic caulking/adhesive using the method shown here at Native Seed SEARCH:

How to Make and Use Ollas

And here is a pic:

elle sagenev wrote:Will they allow that kind of water harvesting near Denver? We go to Denver fairly frequently and there is certainly open land. I just imagine it would cost a small fortune to purchase any of it. I like the idea though, quite a lot. <b>The trenches would also help capture snow, which is a lot of our precipitation.</b>

If your intent is to collect snow, investigate using snow fencing (with the swales being the place where the blowing snow is collected. You'll need to pay close attention on which direction the wind is blowing during most blizzards.

Please note: Swales are NOT trenches. They are actually quite shallow. The are never intended to store water on the surface, and in fact, they need to have plants growing on the surface, to armor the soil from the sun's UV rays, and when the water is "slowed, spread, and sunk", it is actually stored as liquid carbon in the plant's roods, and in the composting organic matter that results when the plants are trampled by livestock, (or knocked down by rolling). It's like mulch with roots.

The intent here is to increase the <b>effective infiltration rate</b> of the precipitation into the soil.  Colorado water law does not allow water to stand on the surface for more than 72 hours! If there is an active intermittent waterway, care must be taken to not actually "impede the flow" of the surface water. You CAN use a leaky weir to cause the water to spread out (and hopefully be absorbed by the plants). What has been shown to happen is the water ways become clear and often begin to flow year-around, being fed soil-filtered water from underground. instead of silty run-off.

The water laws are mostly backwards: they actually result in LESS water (and dirtier) reaching rivers.

I hope this makes sense to you.

I agree with others who are talking about maximizing the effectiveness of your landscape's carbon/water sequestration via contouring and mulching (chop n drop!!!).

My big suggestion for dry areas is trees.  Nut and fruit trees are much hardier than vegetables.  See J Russell Smith's Tree Crops (free pdfs online).  Trees are also good synergy with animals.  Grazing animals among trees, and feeding them fruits/nuts.

Cheers,
-b

If the terrain is appropriate, it might be useful to look at the way irrigation systems were constructed by Native peoples such as the Mogollón. They would have the water channeled down rocky hillsides into cisterns. Of course the entire community cooperated, whereas in modern situations you will often run into problems due to multiple ownership of the needed hillsides. But even with moderate or minimal slopes you can direct the flow of runoff.

Hey, Victor, where can we find out more about how the Mogollon irrigated and grew food in arid regions like we're discussing? I'd love to dive deeper into that. We see evidence of them and other groups all around us out here, and I think we probably already use some similar techniques, but we're always looking to learn more, both from the land itself (and the animals and plants currently here) and from the people who were here before us. Thanks!

Thanks so much for your kind words, Kim! Do you mean a new thread? I can try to put something together, but it probably wouldn't have many pictures. Would it still be worthwhile, you think?

Shane Kaser wrote:I agree with others who are talking about maximizing the effectiveness of your landscape's carbon/water sequestration via contouring and mulching (chop n drop!!!).

My big suggestion for dry areas is trees.  Nut and fruit trees are much hardier than vegetables.  See J Russell Smith's Tree Crops (free pdfs online).  Trees are also good synergy with animals.  Grazing animals among trees, and feeding them fruits/nuts.

Cheers,
-b

I agree with Shane. Trees will always be a good choice in drought prone areas, especially with swales. And I would add that it would be good to expect and plan for more and less rain than fifteen inches. Climate change and natural climate variation both will cause inconsistency

Beth Wilder wrote: Do you mean a new thread? I can try to put something together, but it probably wouldn't have many pictures. Would it still be worthwhile, you think?

I think a new thread would be very worthwhile.  Every example of what someone has accomplished makes a huge impact.  I'm familiar with a lot of the desert gardening and greening the desert threads, and I can't think of any where the permaculture is done in the SW US without well irrigation...except for a few on tree planting, I think.  But not kitchen/market type gardening.  I'm impressed with what you've decided to work with.

So much of desert permaculture is disputed as being "impossible" and real world examples have a lot of meaning.

Right now I'm in the midst of listening to all of Paul's podcasts with Geoff Lawton.  He said when the fig trees on the project started producing figs, they told the ag experts the figs were producing (these guys said it was impossible to grow figs on that salty soil).  And the ag "experts" still didn't believe it and wanted "data points".  That story is found in this delightful podcast:
Podcast 281 - Geoff Lawton Q&A Round 2 Part 2

This thread is fleshing out well.  Lots of great comments and ideas!