Wednesday, May 18, 2016

2326. How Soil Microbes Fight Climate Change

By Esther Ngumbi, Scientific American, May 17, 2017

Around the globe, 2016 has been a dusty year. Just this month, massive dust storms enveloped Guazhou County in China, engulfing five-story buildings. Dust storms in Kuwait suspended oil exports, while another  storm engulfed the Texas Panhandle. In January, red clouds of dust swept across Free State, South Africa, while scientists warned that the erosion of nutrient-rich topsoil threatened food security.

But the loss of soil also presents a less obvious challenge: it robs us of a key ally in fighting climate change. That ally is soil microbes.

Global soils already hold three times as much carbon as exists in the atmosphere, and there’s room for much more. According to a recent study in Nature, enhanced carbon storage in the world’s farmland soils could reduce greenhouse gas concentrations by between 50 and 80 percent.

To realize this stunning potential, farmers would need to adopt certain game-changing farming practices that restore depleted soils, largely through spurring the activity of the soil microbiome, a web of microscopic life that includes fungi, nitrogen-fixing bacteria and trillions of other bacteria that promote plant growth. Like the microbes that live in and on our bodies, helping us with everything from nutrition to immune responses, soil microbes are allies. They can help us deal with many of the climate challenges facing agriculture.

Indeed, we are just beginning to understand how to harness the potential of soil microbes. Research has shown they can help restore degraded soils, including land in Mexico’s southern Sonoran desert. This capacity gives soil microbes the potential of revolutionize agriculture. Healthier soils produce higher crop yields, hold water more effectively, sequester more carbon and allow for increased agricultural productivity on existing land.

Secondly, soil microbes can help plants tolerate hot temperatures and drought brought about by climate change. Recent research has shown that soil microbes can help plants like wheat, rice , pepper and maize to withstand drought. Plants treated with soil microbes have a deeper root system and their shoots grow more quickly. Consequently, under drought stress, plants inoculated with microbes can more effectively take up water from drying soil and maintain near-normal shoot growth rates resulting in increased crop productivity.

Thirdly, soil microbes increase plant defenses against insect pests whose populations are expected to increase due to the changing climate. In India, researchers have shown that soil microbes applied directly to seeds helped plants combat the rice leaf-folder insect, an important rice pest in China, Japan, the Philippines and Vietnam. In another study, treatment of cotton plants with soil microbes helped them fight off beet armyworm, by killing its larvae.

What’s more, soil microbes can improve overall plant growth. This is especially important to the world’s 500 million smallholder farmer families, many of whom live in Africa and produce one-quarter of the average global yield of cereal crops . Increased productivity and income would power a virtuous cycle, enabling poor farmers to invest even more in the sustainability and productivity of their farms. The use of soil microbes to improve soil health and mitigate climate change would be invaluable in parts of the developing world hardest hit by drought and rising temperatures.

The challenge is to develop products that work for these smallholder farmers. To date, the handful of soil-microbial products that have reached the market are being manufactured by big companies like BASF, Syngenta and Monsanto. After spending millions of dollars to make these products, which were created for the world major cash crops such as soy and corn, they are unlikely to come at a cost that many small-scale farmers can afford.

Furthermore, to ensure that smallholder farmers benefit from new biological products, research is needed to map out the diversity of microbes in different crops and climates. Once identified, industry needs to develop cheaper methods to grow the microbes on a scale that would be available to millions of farmers.

We can’t expect private sector companies alone to undertake the research and product development needed to serve poor farmers across Africa and Asia. Rather, private companies, public research institutions, governments and other partners need to work together to deliver soil microbial products useful to small-scale farmers in developing countries.

We must continue to protect and restore our soils. We must also invest in understanding and harnessing the many benefits presented by the trillions of microbes that exist in healthy soils. As researchers continue to develop promising new biological products, there is the need to educate and guide farmers to better steward the populations that already exist in their soils. At a time when climate change is threatening our ability to sustainably grow food, protecting the soils that are home to our allies-soil microbes-is a game changer, providing novel solutions to address the challenges presented by climate change. 

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