PHOTO: Natural Resources Conservation Service
Lisa Munniksma
April 12, 2016

Soil is a trendy topic right now. All the farmers—conventional and organic—are talking about it: how to build it, how to protect it, how to diversify the microbial population in it. Whether you’re a farmer or simply a human being, soil microbes are kind of a big deal. They break down organic matter and leave behind nutrients essential to plant health. They create air pockets in soil so water can pass through. There are “good” microbes and “bad” microbes battling it out underground to support healthy plants or to cause plant disease.

Since the United Nations Food and Agriculture Organization made 2015 the International Year of Soils, it seems like everyone is coming on board with the fundamental idea that without healthy soil, we can’t have healthy life. But just as the great weight of protecting, promoting and building soils settles in for farmers and for lay people, scientists go and deliver a punch: Soil microbes aren’t adapting to changing climates. So as our climate changes, the bacteria, fungi and other microorganisms are going to … die? It’s not clear quite yet whether reality is this gloomy.

Your Soil: Old Reliable

For 17 years, scientists from various places, including the Pacific Northwest National Laboratory and Joint Global Change Research Institute, studied the microbiology of soils on a mountain. They switched a sample of soil from one location near the base of the mountain with a sample from a warmer, drier location nearer to the top of the mountain, about 1,500 feet apart. The expected result would be that microbes would change to fit their new environment, but that wasn’t the case. Even though the microorganisms had plenty of time to evolve to reflect a change in climate, they showed very little change.

A warming climate is bad news for soil microbes, regardless of whether they’re able to adapt to their new surroundings. Warmer soils naturally contain fewer microorganisms.

In the tropics, for example, “most of the carbon is tied up in trees and vegetation above ground. In the tropics, the topsoil has very little soil organic matter because high temperatures and moisture quickly decompose it. Moving north or south from the equator, the organic matter increases. The tundra near the Arctic Circle has a large amount of organic matter because of cold temperatures. Freezing temperatures change the soil so that more organic matter is decomposed than in soils not subject to freezing,” according to Ohio State University Extension.

The Solution To Climate Change?

Soil never ceases to amaze me, for as apparently resistant as it is to climate change, it also has the ability to help curb climate change. You might have heard of the phrase carbon farming. It’s capturing and holding carbon in plants and in the soil so carbon dioxide gas—a primary greenhouse gas—is not released into the atmosphere. A study conducted by five universities says sustainable land-management practices can allow the world’s soils to store an extra 8 billion ton of greenhouse gases. (It already holds around 2.4 trillion tons.)



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