Excerpts from Jim Conrad's
Naturalist Newsletter

from the November 28, 2010 Newsletter issued from Hacienda Chichen Resort beside Chichén Itzá Ruins, central Yucatán, MÉXICO; limestone bedrock, elevation ~39m (~128ft), ~N20.676°, ~W88.569°
NO MULCH FOR THE MAYA
In various pictures I've shown you of our organic garden area you may have wondered about the complete barrenness of the soil between plants and beds. Usually in organic gardens you see lots of mulch.

This week I was suggesting how useful placing mulch around plants might be now that the dry season has come. However, before I could explain how mulch helps soil retain moisture and how it enriches the soil with organic matter and nutrients as it decays, the Maya man listening took his machete, flipped up some leaves on the ground, revealed a big, hairy spider, and said:

"Look, that's the kind of thing that plant-trash on the ground attracts. That bicho eats plants. Why attract things that'll eat up your garden?"

I was stunned that a man who all his life has supported his family by cultivating a large milpa, or traditional cornfield, would assert that spiders eat garden plants. Neither would he buy my claim that invertebrates who eat garden plants are not the same species found under leaves on the ground. What I said about soil organic matter and nutrient release simply didn't seem to register.

Later I asked another Maya farmer if he could think of a single instance when the Maya use organic matter to enrich or improve the soil.

"No," he said.

I asked his thoughts about spreading mulch beneath the Hacienda's ornamentals. Though this man knew volumes about local medicinal plants, he now expressed exactly the opposite of what I was taught in Soils Class back at the University of Kentucky. "When dry weather comes, mulch sponges up moisture from the soil, and of course that hurts the plants," he said.

Over the years I've seen many references to sustainable farming techniques of indigenous Americans before the arrival of Europeans. Mainly they were talking about "slash and burn." Cut down a patch of forest, burn it, that releases a flush of nutrients in the ash, resulting in bounteous harvests for two or three years. But then weeds and animal pests invade, the soil grows depleted of nutrients, soil structure deteriorates from erosion and loss of organic matter, and after a few years the plot must be abandoned, the farmers go elsewhere, and start the cycle all over. Once the slash-and-burned plot reverts to forest, it may be slashed and burned again.

Well, this technique is sustainable only in areas of low human population density. When population increases, there's not enough forest to go around, and periods between slashings and burnings shorten until the land no longer has enough time to recuperate. Soil is eroded away or gradually converted to relatively sterile, hard-packed dirt.

More and more I'm thinking that Classic Maya civilization may have collapsed not only because of stresses brought on by overpopulation but also because of destructive, unsustainable farming practices. The Maya never discovered the wheel, except for its use on small toys, and from what I see here they never realized that conserving soil organic matter is supremely important for long-term soil fertility, and that mulch helps soil retain its water during dry spells.

Historically, I suspect that not appreciating soil organic matter and the use of mulch has been a greater misfortune for the Maya than having missed out on the services of the wheel.