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Concentration of CO2 in the Atmosphere

Do We Have a Quorum?

Slide 23 from Common Ground: The Circle of Life presentation by Cat Buxton.

Jessie Haas

Soil is mysterious. We have identified only about 5% of soil micro-organisms, which means we have no idea what we’re doing when we garden, farm, or build. But we’re learning.

Recently, soil scientist Christine Jones introduced the idea of “quorum sensing” in soil microbes. All microbes use chemical signals to sense how many of their own kind are present in a given environment, as well as how many other organisims exist. When a “quorum” is reached, just as at a select-board meeting, the group can take action, turning on and off genes in themselves and their host. In our bodies, this action allows flu or strep to overwhelm our immune systems. In the soil, it appears that when the microbiome senses a certain threshold of plant diversity, it kicks into higher gear, working together, Jones says, “as a super-organism.”

In recent cover crop studies during extreme drought, single-species crops failed. Three species mixes, seven species mixes? Failed. But the farmer running the experiments threw every bag of leftover seed he had into his planter, for his last plot. That 27-species mix thrived on the same inch of rain.

A New Zealand dairy farmer, following Jones’s advice to use managed grazing, bio-stimulants, and reduced nitrogen inputs, grew six inches of new topsoil in three years. When he reported that to Jones, she told him that he was behind the times. To really increase soil fertility, he had to diversify his planting mix. (He had been using only rye-grass and clover.) He planted a 12-way mix on one hillside, and it was growing nicely three months later when Jones visited the farm. She asked him to dig a hole so she could look at the soil.

His soil was whiteish, volcanic material, more recently covered in the new, six-inch dark layer of topsoil. He plunged in a spade and found only a trace of volcanic soil at the very tip of the core. “We must have burned a tree here,” he said, and moved to another place to dig, and another. Fifty holes later, he and Jones were forced to conclude that by the new method, he had grown six inches of topsoil in three months.

Later analysis showed that total organic carbon (TOC) in the soil had tripled, nitrogen and phosphorus levels had increased, Brix levels had tripled, and the land could carry twice as many cows. Milk production increased, and somatic cell count was cut in half.

Reports like this have a counter-cultural, Findhornish quality. One has to pinch oneself and remember that this is science. It’s just that science is showing us a reality larger and more magical than we had previously imagined.

The big lesson here is that biodiversity matters. It’s not just a pretty by-product of clean farming. It’s the engine of a rich new form of agriculture that has great potential to solve our worst environmental problems. That new soil is carbon, drawn down out of the atmosphere and assembled by the microbiome into a luscious chocolate-cake like structure with a great capacity to soak up excess water and hold it in reserve. The plants are more nutritious. The cows are healthier. The farmer has better economic prospects, and the person who drinks the milk will get more benefit.

Soil scientist Walter Jehne speaks of the “cathedrals underground” built by soil micro-organisms. As we mourn the damage to Notre Dame, we can resolve to make this growing season into a building season. Plant more plants. Maximize diversity. Minimize disturbance. Leave no soil uncovered. Extend the photosynthesis season. And rejoice. It all matters, and we can all help.

The meeting will now come to order.

Jessie Haas has written 40 books, mainly for children, and has lived in an off-grid cabin in Westminster West, VT since 1984,

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