Steven Shafer, soil scientist

This researcher is working to meet the looming calorie demands of an emerging population of 9.7 billion by 2050 through soil health. Interview by Anna Katrina Hunter.

April 02, 2018

Steven Shafer. Photo: Soil Health Institute

Steven Shafer is Chief Scientific Officer at the Soil Health Institute, which aims “to be to soil what NASA is to space.” He spent 33 years at the USDA Agricultural Research Service before coming to the institute.

Shafer studies the “phytobiome”—the environment that plants inhabit along with their surrounding organisms—and how it influences soil health. Shafer thinks that studying the phytobiome can help solve a potential food crisis: Currently, the world’s population of 7 billion people are fed by arable land that comprises 10 percent of Earth’s land mass. By 2050, it is estimated there will be 9.7 billion people, but crop yields are peaking. To counter this problem, Shafer says scientists should consider the numerous factors that affect crop yields, such as insects, microbes, weeds, weather, and nutrients. Scientists typically look at one interaction at a time. But examining these factors more holistically, Shafer says, might help farmers predict which crops do better under certain conditions, enhancing their performance and yields.

SciCom's Anna Katrina Hunter sat down with Shafer in February at the American Association for the Advancement of Science annual meeting in Austin, Texas.

How long have we been studying microorganisms in the soil?

Since the late 1800s. We have known about microbes in the soil for many years, and it has paid off in big ways—such as antibiotics that have come from soil microbes, like Strepomycin. Penicillin grows on moldy fruit and bread. In recent years, we have seen an explosion of molecular techniques to study what is in the soil in new ways, as opposed to trying to culture microbes in petri dishes.

What is soil health?

When you go to your physician and get a physical, your blood pressure is 120/80, so are you healthy? In the soil, there is a range of things that need to be measured. Once we started to get a handle on the idea of the soil being a vital, living ecosystem that could be healthy or unhealthy, the idea [of soil health] started to catch on.

What is the phytobiome?

The phytobiome is the total biome that plants find themselves in, from the animals that we can see all the way down to viruses. These organisms are not only in the soil. They are associated with the plant roots; they splash up on the leaves, stems, flowers and fruits.

All of that becomes extremely important in plant health, from the standpoint of how those organisms affect the decomposition of carbon, the turnover of nutrients, and how they may cause plant disease directly. It is very complicated, and you have to look at it as a whole. Soil health has huge impacts on plant health. It is almost impossible to talk about the phytobiome without talking about soil health.

How is it useful to study the phytobiome?

Some research has explanatory power. How does this physical, chemical, biological system work? If you get good at explaining how it works, you can start predicting how it will respond to some sort of change. Then you have a basis for making decisions.

I know someone who does research on how proton pumps in chloroplasts work in soybeans. If you can explain how those proton pumps work really well, then you can predict how they might respond to a high CO2 environment. And if you know how that happens, then you can look for certain soybean genetic types that have the right kinds of chloroplasts that will take advantage of the high CO2.

It is an ability to explain how something works. If you can do that, you can predict, then make decisions.

"If you really want to help the world, figure out how to produce more calories in the 21st century."

Are we going to keep finding new microbes?

Absolutely, I am sure there is a new organism being discovered every day.

The human global population is predicted to reach 9.7 billion people by 2050. Do we have any evidence that we can support that kind of population? Where do soil microbes and the phytobiome fit into this?

I think we have to be hopeful. I don’t think we can sit back on our heels. By one estimate, we have to produce as many calories in the 21st century as agriculture has produced in human history up until the 21st century.

You have three ways to do this. You can put more acres into production, which is probably not going to happen, since cities keep expanding and encroaching on the best farmland.

You can waste less. In North America, we waste as many as one-third to one-half of the calories that are produced.

The last one is getting more out of every acre. This concept is called sustainable intensification, to sustainably forever get more out of every acre. I would not advocate that we can continue that idea forever. We know that in a lifetime, [crop] yields can go up with improvements in crop breeding, water management and so forth.

If you really want to help the world, figure out how to produce more calories in the 21st century. Think about the science that has to go into that. What greater challenge is there? And what greater benefit to humanity then to figure it out?

Would you say looking at the entire biome of the plant, from its flowers to its roots, is one way to achieve more sustainable intensification?

An awful lot gets left in the field. How do we capture every last piece of grain? How do we keep fresh produce from spoiling as quickly? I think the phytobiome and soil health is an important part of it. It is not a silver bullet. We are not going to find one bug that is going to cure it all, just as we are not going to find one area of science that is going to enable us to do this.

For those who are skeptical about sustainable intensification: Is it wishful to think that 2.5 billion people won’t show up and we won’t need to feed them?

The good thing is that they are having the conversation. It may be some opportunity for some education. Precision agriculture is not going to be the silver bullet to fix everything. The phytobiome and sustainable intensification is a concept. It is a goal.

Diversified intercropped systems, for example, are highly productive.

Why is that? If there is a diversity of plants in the system, there is diversity in the root system, which promotes the diversity of the soil microbial community, and in turn promotes plant health.

Is there anything I haven’t asked that you would like to share?

My hope is that you communicate to your readers the connections between plant health and soil health as part of the same systems approach to feeding 9.5 billion people. That just amazes me when I think of that—another 2 to 2.5 billion people between now and 2050. Seven countries the size of the U.S.—put that on the globe. How do we handle that?

I think part of that is explaining, predicting and making decisions on soil health. The phytobiome will be part of it. It will not solve all the problems, but it will definitely be part of it.

© 2018 Anna Katrina Hunter. Explore Katrina's personal plot of articles at