[LINK] "Mars Farming Gets Green Thumbs-Up"

[rfmcdonald]

Wired Science's Brandon Keim reports on a new study suggesting that Martian agriculture is feasible, notwithstanding the very different physical conditions of that world, including some which could create problems never before experienced (or even hypothesized).

Growing plants in soil on Mars might seem old-fashioned for those raised on the futuristic prospect of hydroponic or aeroponic agriculture, in which crops sprout soil-free nutrient broths or mists.

But in recent years, starry-eyed biologists have come to appreciate the importance of soil-dwelling microbes to plant roots and soil processes. Moreover, soil-based agriculture is backed by thousands of years of human-based research and development, and millions of years of natural evolution.

“Mechanical systems are very reliable over short-term expeditions,” said Maggi. “But soil can control itself. In terms of operation error, it’s more reliable. Plants provide more benefits in terms of energy and health. And real soil performs operations that other systems cannot.”


However, there are many unknowns about extraterrestrial agricultural biology. Among the most important is how low gravity will affect the flow of water and nutrients, and in turn microbes. Once water and nutrients get into the plants, capillary action will take care of the rest. But getting them there is the key.

“If there’s low gravity, water will not flow down so quick. The transport of nutrients would also be slower. If transport of nutrients towards root microorganisms is not fast enough, it will suffocate them,” said Maggi.

In a July Advances in Space Research study, Maggi and University of California, Berkeley biogeophysicist Céline Pallud simulated both Mars- and Earth-gravity root processes using BIOTOUGHREACT, a well-regarded model of soil nutrient transport and microbe dynamics developed at the Lawrence Berkeley National Laboratory.

The simulation suggests that slower water transport is actually a good thing, preventing water from falling through the soil and being lost, along with the nitrogen it absorbs on the way.

At Mars gravity — about one-third of Earth’s — up to 90 percent less water would be needed than in a terrestrial greenhouse, said the researchers. Much less nitrogen would also be needed.

“You don’t have a leaching of nutrients. The nutrients you put into the soil, remain in the soil. You don’t lose them,” said Maggi. The simulated bacteria thrived on all this extra food, reaching densities between five and 10 times the usual.