Wednesday, August 30, 2017

Dry farming (in a sense)

I try to grow most of what we eat. There are a lot of reasons for this, many of them health related. Argue as you will, our water, air and soil is scarcely healthy and we add stuff to them that makes it worse. When I plant, I know precisely what is going into my plants, into my soil and into my mouth.

I can't grow it all at this point, but I'm working on what I can.

Part of the problem with growing in this area is water. I use far too much water for thirsty lawns (which will be going away at the first opportunity!). Other than that my major water use is for food producing gardens, fruit trees, and grape vines. Unfortunately, municipal water is well known for harboring such gems as pharmaceuticals, industrial byproducts and agricultural waste. Then there's the nasties that we ADD to the water to make it "Safe." Right.

The best option then, would seem to be to produce only what I can grow without municipal water. Or maybe not. That would be a yard full of sand and rock, basically. I've done work to make the area more self sufficient, but it works to a certain point and then I have to look for something else that take me that tiny step closer to my goal.

I started doing some research on dry farming, farming that relies only on the water available on a site rather than irrigation or municipal water. From my research it appears that dry farmers fit primarily into two categories.

1) Farmers who farm during the growing season in areas with high humidity, low seasonal temperatures, mild winters and deep, rich (primarily clay) soils. The information I've been able to find indicates that soil between 6 and 8 feet deep is ideal, deeper is better. It must be a mix of sand, clay and organic matter to hold the water with no impermeable or partially impermeable layers to stop water flow.

2) Farmers who leverage mild winters and plant their primary crop (often winter grains) when the rains are falling (September through May) then harvest in the spring. These farmers can grow on poor soils, have low humidity, but also low seasonal temperatures and mild winters with little or no snow.

I do not fit in either category. My soil is straight sand, with a layer of rock underneath. Temps consistently get up into the 100's in the summer and below freezing in the winter. On the other hand, I have grapevines and fruit trees that have thrived with little water for 30 + years, digging their roots deep. So it is possible.

Additional research brought up a third group, farmers who grow in arid to semi-arid lands, in areas that have harsh winters and brutal summers. In fact, the original definition of "dry farming" included only those areas that got less than 20 inches of precipitation per year. By this definition, #1 up above isn't dry farming, or only in the loosest sense, in that they do not use irrigation or municipal water.

So with dry farming defined, how do I use it?

The basic principles of dry farming seem to be:

Keep the water in the soil
Soil treatment
Choose crops that work
Plant drought tolerant varieties
Fallow season
Plant spacing

Water can be kept in the soil through a variety of techniques--mulching (either dust mulch, organic mulch, or rock mulch), covering the soil, shading the soil, controlling wind, and controlling temperature. Water primarily leaves by going up or down--evaporation or dripping down to the water table. By choice, if you must have one or the other, water table is probably best since the roots can chase it down. Evaporation can be used, providing you have sufficient ground cover to catch the evaporating water and return it to the soil. Ideally the soil should be a clay loam, but we're not doing "ideal" here. High organic matter is of utmost importance. If you start with poor soil, work to amend it until it can be used.

Soil is a loose web of particles of various sizes. Water is a perfect (liquid) crystaline matrix. Through adhesion it will try to fill the space with itself, climbing up through the soil if there is a path for it. That path is created by the density and makeup of the soil. By lightly packing the soil under a seed, you create the path for the water to fill that space, wetting the soil if there is any water in it. Traditional dry farming uses multiple implements to bring the water up from deep underground. It also pulverizes the soil on the surface to prevent evaporation in a sort of dry (or dust) mulch. Originally it appears that this process was used because organic mulches were not available in the areas where dry farming was pioneered. Even now, organic mulches on the scale required by a dry farm are impractical at best.

Choose crops that create a large root system. Many "modern" varieties have very little root, since they're intended to be grown under irrigation. Primary crops for dry farming must be able to chase the water, rather than having it come to them.

When you've chosen your crop, choose varieties that are specifically drought tolerant, and that doesn't mean drought tolerant under irrigation. If it can't thrive under those conditions, it doesn't deserve to be planted. Look for phrases like "prone to cracking" or "don't water too much" because these indicate a variety that may do better with less water. Heirlooms are likely to be more drought tolerant than "new" varieties.

In arid areas it is necessary to let the soil moisture build up over an extended period of time. Every other year planting is ideal, but at minimum every four to five years the soil should rest and collect water. Letting an area "lie fallow" also increases fertility, particularly if you cover crop or have animals on it during that period. Taking into consideration that a cover crop (according to the information I found) will use up part of your stored water.

And last, plant spacing. This seems to be key in dryland farming, and this is where I have the hardest time fitting my head around it. With the basic principles of dry farming, plants are to be given a great deal of space. The idea seems to be that with less competition the plant roots will spread further, with more space to take water from, and produce more. This may be the case. I don't know, as I've never tried it. I have a 30 x 50 foot garden and planting five or ten feet apart simply isn't practical. With pumpkins or other squash I can almost see it, since they spread to fill the available space. But corn? Beans? Tomatoes? Potatoes? In fact, the information I read said potatoes should be spaced even further apart than that. Supposedly, without the competition of other roots in "their" space, the plants have more available water in the soil.

I'm not sure this plant spacing business makes sense, but I'm going to try it next year in a small area and see what happens.

On my scale I have no problem finding organic mulching materials, and dust mulch might as well be Santa Claus since I have no clay in my soil. I can plant under and around trees, create windbreaks, and plant in partial shade. I have plants I think will work for waterless planting and I'm going to try deep watering, watering through a pipe to force the plants roots deep.

Every outside input becomes a handicap if it's ever unavailable. Right now that means I need water independence, so that is what I'm working toward. Maybe it'll never happen, but each failure and success brings me closer to the ideal.

First Update

Second Update

No comments:

Post a Comment