A man holds dry earth from a wheat field in his hands, in this photo illustration, in Niort, southwestern France. REUTERS/Regis Duvignau
This World Soil Day, take a moment to reflect on the importance, and the state, of our soils. Healthy soils underpin our environment and agriculture: soils grow our food, anchor our ecology, and are the foundation of food security, biodiversity, and ecologic resilience. But despite their immense importance, we have only begun to understand the complexity that make soils a cornerstone to ecology and agriculture. Until around a decade ago, many scientists only studied soil chemistry, if they studied soil at all. Today, however, scientists know that the billions of microbes that live in the soil act as their own ecosystem, a living, breathing network—a network, called the soil microbiome, that accounts for a quarter of the world’s total biodiversity.
The health and presence of a microbiome is the difference between soils—the rich, fertile earth that supports life—and dirt. These microbiomes cycle nutrients and maintain the fertility of the soils that allow plants to grow and flourish; but more than that, the soil microbiome acts in many ways as an extension of the plants themselves, helping plants grow, fight disease, and provide resilience to environmental stresses such as high temperatures and drought. This ecosystem within the soil is the foundation much of the natural world we see rests upon: from grasslands, to forests, to agricultural fields. And as science increasingly discovers, the fate of these visible environments is deeply interconnected with the invisible environments in our soils.
Healthy soils are vital to productive farms, but farming, as a practice, is quite hard on soil: it reduces soil biodiversity and nutrient content, and after subsequent harvests, soils can become exhausted, unable to support bountiful harvests. But understanding the complicated relationship between plants and the soil microbiome is a first, vital step towards understanding how farming can limit its impact on soils, and even help regenerate them.
Recent work by the Netherlands Institute of Ecology, for example, has placed the soil microbiome at the center of efforts to restore the ecology of degraded agricultural land. Researchers at the Institute have created successful ecosystem restorations through soil transplants: they remove depleted top soil from an exhausted field, and replace it with a sprinkling of healthy soil from grasslands or forests. In a few years’ time, those once-depleted fields regenerate as grasslands or forests of their own—taking on the habitat of the soil-donor ecosystem. Not only does this process show great promise in the restorative possibilities within soils, but underscores why soil science is launching a startup race for new companies hoping to capitalize on techniques to improve the soil, its microbiome, and the health of the plants and crops it supports.
Nitrogen is one area where this innovation race has the highest stakes. Plants need to absorb nitrogen from the soil to thrive, but in order for that nitrogen to get into the soil in the first place, nitrogen—normally a gas in the air—has to go through a process called “fixing.” Fixing is a slow, energy-intensive process: natural nitrogen fixing is done one molecule at a time by bacteria, and industrial nitrogen fixing consumes 2 percent of the world’s total annual energy supply. Industrial nitrogen fixing allows the manufacture of nitrogen-containing fertilizers that enable modern-scale agriculture, but for farmers at the global margins, such an energy-intensive product isn’t always reasonable. For them, unlocking the potential of nitrogen-fixing bacteria may be the best route, and groups like N2Africa are already leading the way. One of the only non-fertilizer ways for farmers to add nitrogen to their fields is to grow crops of legumes—plants like peas, peanuts, and soy—which house nitrogen-fixing bacteria in their roots. N2Africa helps to maximize the nitrogen output of these plants by creating inoculants, a product that adds nitrogen-producing bacteria to the soils. These bacteria need to grow alongside legumes to produce nitrogen, but by making sure that farmers’ fields are full of the necessary bacteria before farmers plant their legumes, N2Africa helps tip the scales to ensure that legume crops leave behind as much excess nitrogen for the farmers’ next harvest as possible.
Microbiome research has impacts on food safety, too. In sub-Saharan Africa, a company called Aflasafe is working to tweak the soil microbiome to promote food safety and security for smallholder farmers across the continent. In much of Africa, mycotoxins—a family of small, soil-dwelling fungi—are ubiquitous, and one, aflatoxin, lives in many agricultural soils. But aflatoxin is toxic, and when it contaminates crops, it poses a real food safety problem. Aflasafe’s product protects foods from aflatoxin not by neutralizing the toxin, but by minimizing aflatoxin within the soil microbiome. Aflasafe contains non-toxic species of mycotoxins that, when applied to agricultural soils, thrive and out-compete their toxin-producing cousins. This doesn’t just reduce the toxins found on crops, but actually changes the ecosystem of the soil, creating low- or toxin-free growing conditions for seasons to come.
Microbiome research has applications for large-scale, industrialized agriculture, too. Indigo Agriculture, for example, is one startup working to create commercialized treatments to help lessen the environmental impact of some of the more environmentally draining farming practices, such as cotton farming. Indigo creates a coating for seeds made of an optimized mixture of those microbes that help build healthy soils, and sells these to farmers looking for ways to improve their soil fertility and health. The product is still in development, but in 2016, Indigo-treated cotton seeds were planted and harvested on more than 50,000 acres, the largest application of this technology to date.
Our modern agricultural system is enormously effective, but to produce ever greater yields, agricultural science can leave no route unexplored. By unlocking the potential within our soils, many see a way forward to protect the environment, better farmers’ wellbeing, and further ensure food security. Research in this field isn’t easy, and neither will commercializing a product that will benefit wide swaths of farmers the world over. But to move agriculture forward, and to find those next generation technologies that will help feed a growing planet, expand farmers’ margins, and bolster agricultural ecology, it’s absolutely necessary.