Tuesday, June 30, 2009

Mr. Fungus, Meet Miss Bacteria

The miracle season has started in San Miguel. It's raining almost daily, sometimes in shy, intermittent drizzles or like last night, in hellacious rainstorms, frightening in their intensity and suddenness. Almost overnight, arroyos, culverts and even cracks in the ground that had lain silent for seven or eight months are whooshing and gurgling again, in turn jolting stagnant lagoons and reservoirs back to life.

From one day to the next a bright green fuzz of vegetation covers the desert ground. Sheep, goats and burros that used to meander morosely past our fence scrounging for any kind of edible vegetation seem livelier and certainly fatter, now that the landscape is an endless salad bar.

This ephemeral subtropical spectacle, complete with relatively high humidity, will continue until November, when a grand finale of mostly sunflowers, daisies and cosmos--millions of them--will cover the landscape in all directions. Then it's back to several months of drought, brown fields and caked soil.

Yes, that San Miguel soil. At the ranch, once you get past the thousands of rocks, a shovelful of the stuff right now looks black, spongy and downright promising. It's not Iowa--the prickly pear cacti remind you of that--but it seems like a close approximation.

That is until you try any gardening: The soil's consistency ranges from asphalt (winter) to goulash (summer). Right now we're in the goulash season when the soil is soft enough to sink a shovel, at least until you hit a rock. It's certainly preferable to winter asphalt, when the garden tool of choice is not a shovel or a pitchfork but a pickax.

Aside from its consistency, the soil has a couple of other problems. Nitrogen, the essential ingredient for growing things, is quite scarce in our soil, which is also alkaline, as is usually the case in this type of desert/savanna region.

As you might imagine, the third problem with our goulash is that it doesn't drain very readily. Swamplike conditions prevail on the farms around the ranch after a heavy rain.

Last year, before we built an access road to the ranch, we had to park our car and walk half a mile across a recently plowed field where we sank past our ankles. Our feet each became 10-lb. clumps of intractable mud.

On the ranch itself it isn't very muddy, but that's because we have another problem--erosion. There's a slight pitch on the back one-third of the land that becomes a more precipitous drop-off in the front two-thirds. The house is going up on the ridge before the drop-off, to take advantage of the view of the valley below.

When serious rains break out, rivers of water and mud quickly organize. I'm convinced the reason our land is not pure rock is that during downpours soil from the farms around us helpfully slides into our property at the high end to replenish what we're losing down below.

In trying to alleviate the shortcomings of the soil and terrain, we've added another complication: We'd like to stick to a generally organic gardening regimen.

Nothing too hard-core. It's just that we plan to grow some vegetables and fruits and we'd rather not place chemicals and pesticides between the soil and our guts.

Besides, after spending all that time and money on sustainable building design and gadgetry, rainwater harvesting and the accompanying ecological blah-blah-blah, it wouldn't look very good to douse the outdoors with the latest from Dow Chemical or Monsanto, would it?

With those considerations in mind a couple of weeks ago we attended a lecture at the local botanic garden on organic ways to improve San Miguel's problematic soil. Perfect, we figured, although the title, "Soil Microbiology: An Audiovisual Presentation," suggested we weren't in for a rerun of "Dancing with the Stars," featuring Mario López and his dimples.

Indeed, rather than a shot of organic adrenaline the lecture left us scratching our heads. Throughout the 90 minutes or so, our minds went from the excitement of hope, through a brief pause of uncertainty--and straight to confusion.

It was "Aha!" followed by "Hmmm..." and then "Huh?"

To summarize, there's a constant battle going on in the soil between bacteria and fungi. Ideally each camp should keep each other in relative balance, but in San Miguel bacteria are running rampant. Our soil is best suited for weeds. How one fixes that--without buying a microscope, hiring consultants and spending oodles of time and money--never became quite clear.

The presenter was a thirty-something Canadian who was extremely knowledgeable and articulate, with an enviable enthusiasm for his field of expertise. His is not a job but a cause. Great lecturer. He came to San Miguel two years ago, is training to become a Certified Food Web Advisor and has set up a consulting firm to help large land owners, some of them near to where we are building, to establish "organic land management systems."

Our soil is muddy and lumpy because sodium ions bond the clay together. We need carbon to counteract sodium's effect. Mixing in rich compost could do the trick.

Aha! We had bought a truckful of compost from a neighboring mushroom farm. A year ago, mushroom compost was the rage among gringo gardeners in San Miguel, in large part because the farmer was giving the stuff away. "Free!" is always the surest way of catching the attention of San Miguel's Social Security set.

The young Canadian quickly sank our hopes for a quick solution. It turns out the compost is a practically lifeless, nutrition-less residue of mushroom farming. It even contains some salts which is the last thing you need in our alkaline soil. Hmmm.

When hearing such complaints the mushroom farmer supposedly began adding some manure to the compost. That sounds like a good idea, but...

Manure contains bacteria, which are rampant in our soil. Someone suggested adding worm castings to the soil, but that's also bacteria heaven. That problem perhaps could be remedied by feeding the worms more cardboard instead of green matter like lettuce or vegetables. Compost from kitchen scraps? Nope, that's more bacteria.

The kind of compost we need would be from wood chips--from certain kinds of trees, mind you--that would bring in carbon and fungi. Someone suggested perhaps adding sawdust to the compost pile, but that would depend on the type of wood they were cutting at the lumberyard.

After talk about spraying "compost tea" to facilitate the production of fungi in your garden, the lecture careened toward the Huh? moment.

What exactly--and realistically--do you do to bring about that vaunted equilibrium of fungi and bacteria in your garden, after which the ideal soil biochemistry supposedly could sustain itself? Even Stew, who as a biology major in college has a far greater interest in nematodes and protozoa than most people, seemed stumped.

One solution would be to hire the lecturer as a soil consultant for $50USD an hour, and send packets of soil to the U.S. for analysis for about $220USD a shot. But even then the prospects of essentially reconstituting the soil on a large parcel of land sound daunting to near impossible.

Enter my friend Jo Ann. At their ranch at the other end of town she and her husband had built raised beds, about three feet high, where they raised vegetables. They used drip irrigation and covered the beds with a screening gauze to protect the crops from both the scorching sun and insects.

Underneath the protective cover robust vegetables seemed to be jumping out of the dirt.

So I contacted her, asking for some of her raised bed secrets:

Regarding our raised beds. What we did was a third composted manure (we used horse/burro and chicken, both of which we had since our animals created it) a third construction sand and a third compost that we made from kitchen/farm scraps. Our beds were about 3 1/2 feet tall so we filled a lot of the bottom with gravel to get good drainage. I never used the mushroom compost and found that the "rich soil" that you could buy from the nurseries often contained maggots and other very large bugs that were more of a problem in the garden then the benefit the soil provided. Hope this helps.

It sounds like a reasonable plan, though we need to find some cooperative farmers who will supply the animal manure for composting.

Regarding our pile of mushroom compost, we will continue mixing it equal parts with tierra lama, a sand-like loam used by some local landscapers to help break up the clay soils. We'll use the mix to backfill the holes of the trees we are planting; it should be helpful in breaking up the clumpy black soil if nothing else.

As for the apparent bacteria v. fungi imbalance in our soil, the answer for the moment appears to be: Huh?

1 comment:

  1. The role of fungi in soil is to spoonfeed minerals to the roots of plants. They convey the minerals to the plant in some groupthink way of knowing how to do this. The bacteria have a valuable role. Note how the bacteria doesn't eat the plant while it is alive. Bacteria break down organic materials from complex combinations to basic components. Take horse manure. It arrives at your site as fecal matter mixed with hay or straw and horse urine. The composting process either in a compost pile or by direct application to the soil transforms those elements using the catalytic action of bacteria. Nitrogen naturally gets released. When the manure is added directly to the soil, the bacteria fixes the nitrogen into the soil to make it available to the plant. Rye grass fixes nitrogen by binding it with the the soil as well. This is why Rye grass is called a green manure. Fungi and bacteria are present in manure-based compost. As you dig through a compost pile, you see layers of blue mold even deep down. The bacteria and fungi are present together from the beginning of the compost process. They do different work like carpenters and plumbers and don't seem to bother each other.

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