Cactus and horse manure – cement shares to plummet?

On a mesa close to the Mexican border a dozen men and women scooped up handfuls of mud and hurled them at the sides of a small adobe building. They stepped back, admired the sound and effect of mud hitting the wall, and reached for another helping. It bothered no one that the secret ingredients in the mud were prickly pear cactus and fresh horse manure that had been cold-brewed in a “tea” before being mixed with earth and straw.

Rather than focusing on the upscale housing market in such places as the Albuquerque-Santa Fe-Taos axis in New Mexico or the wealthier areas of Arizona or California, the alliance is in the forefront of a renewed effort to build energy-efficient housing using materials that considerably reduce the cost and the impact on the environment.

“It’s all economic incentives because dirt is the only (building material) that is not linked to the price of oil,” said the seminar spokesman. The project was under the watchful eyes of Maria Jesus Jimenez, who managed the sessions; Joaquin Valenzuela, an adobe vault and dome craftsman; and Efren Rodriguez, a master adobe plasterer. All hailed from Ojinaga, Mexico, across the Rio Grande from Presidio.

That morning’s assignment was to replaster the walls of a 12-by-12-foot domed adobe building that is a guest quarters for Swan’s 1,600-square-foot adobe home. The smaller building originally was plastered with a cement-based covering - a move Swan said was a mistake. Unusually heavy rains last summer produced hairline cracks in the plaster, and they could not be patched. So the old plaster was peeled off the walls, broken into small chunks and recycled as walkways around the yard - blue paint and all. This time, Swan said, the plaster would be based on the cactus-and-horse-manure mixture instead of commercial cement.

The prickly pear pads were cut open and then soaked for three days in water, which produced a syrup like consistency that helped the mud adhere to the adobe blocks. The manure soaked separately for three days, and unlike the cactus liquid, it was poured through a wire mesh strainer before the liquid was added to the dirt in the mixing process.

Blocks made from adobe also help keep a building cool in the summer and warm in winter by absorbing and then releasing moisture in the air as needed. A well-built adobe house can be as much as 20 degrees cooler in summer than the air outside.

(Abstracted from The San Antonio Express-News).