So it's that time of year for me... 30 minutes of chicken chores a day = lots of time for "professional development."
I recently stumbled across a methodology from sub-Saharan West Africa locally known as "Zai Pits." I'm curious to know if a) anyone here has hands-on familiarity with the practice and b) what the opinion of more seasoned horticulturalists might be.
The short version is that they dig a pit roughly the diameter of a 5 gallon bucket 4-6" deep, then put a layer of organic material in. They then direct-seed and topdress with the indigenous soil, leaving an inch or so of the hole unfilled. It's supposed to work as a micro-catchment for rain, with the added benefit of the slow-release of NPK & micronutrients from the organic material (usually cured manure but sometimes they just use them to dump compostable waste)
I think that it's an efficient way of concentrating physical efforts on each plant. In the desert SW, it would be effective, especially if it were used to introduce potentially deep rooting cliche-breaking plants such as daikon radishes or other pioneering plants.
The method has the added advantage of concentrating hand-watering irrigation efforts to specific plants by providing an ample organic sponge around the high-value plants. Agriculture is not usually a naturally developing process in the desert. Do not try to make your desert garden look like something you'd find in wetter climates. The zita pit is useful, but not necessarily sustainable. It may, however, be a way to establish a tempory yield that you can eat until your more permanent agriculture becomes established, and it may be a way of establishing and maintaining your permanent plants until they can establish deeper root systems of their own.
If you observe the natural desert environment, the spacing between plants in extremely dry environments often builds up organic and wind-blown materials around specific plants. Mounds form, but short heavy rains cause the water to pool at a point midway between the plants, where the plant's shallow horizontal roots would be. A potential drawback is that a hard patina tends to form in the cleared areas, which deters microbes and other biotas. (note that earthworms are not native to the deserts, and will not survive without ample ground cover and litter. Other biological species must take up this niche in the harsh desert climates.
The point is, you must carefully select which water conserving/using scheme you need to use for the specific yields you are shooting for. What is your intent? if it is to protect an annual, like a corn plant, the zita pit may be the way to go. If you are looking to establish a catchment for directing short but intense cloudbursts, you may want to consider how a zita pit might be used in conjunction with other earthwork designs.
The Zai pit is quite similar to how the Native Americans in the East planted corn. Except we used fish for the "organic material" mostly because fish were pretty easy to come by.
These work great where there is little in the way of rain in the dry season. If you get rain all through or through most of the year, these should work very well for planting crops.
Keep in mind that some crop plants don't want or need a lot of rain being held near their roots but are adapted to sinking roots deeper to find water, which is one of the functions of that organic material placed under the seed bed.
The other reason for it is to get organic material into the soil at a level where it won't go away quickly (surface or just sub surface organics in semi desert areas will go away before a year is up).
So I'm not in a desert in the traditional sense, but rather a desert by definition, in that we receive so little rain per year. I view the zai as a structure not unlike a high tunnel, in that it would allow me to extend the impacts of rainfall rather than extending the length of the season.
Part of what I've read about them seems to indicate that they're traditionally used not only for cereal grains and maize, as well as veggies, but that they can also be used (modified for plant type and size) for trees and shrubberies. I can envision utilizing them to create more than a few of the impractical approaches to Perming that I'm reading about here, such as the living fences and food forests.
In the spirit of full disclosure, Bryant, I use my chemical-free horticultural goals as an excuse to go fishing 6-8 months out of the year. From my perspective, it makes my license, poles, tackle, and bait all business expenses.
Ask me about my grandchickens!!!
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