Digging Deep: How to Feed the World With Perennial Food Crops

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How to Feed the World with Perennial Food Crops: A Deep Dive

A well-known researcher talks about crops that might be able to keep up with the world’s growing population.

By 2050, there will be more than 9 billion people on Earth. They will have to find a way to eat, but we are already running out of ground that can be used for farming. And many types of farming, like conventional farming with annual crops that need to be replanted every year, leave fields without enough nutrients, which lowers their future output.

But soil scientist Jerry Glover is hopeful that more people can be fed while farming soil is protected. He thinks that the answer is to pay less attention to annual crops, which make up most of the world’s farming, and more attention to perennial crops, which can be taken more than once without having to be replanted.

Jerry Glover, a soil scientist, shows off a perennial wheatgrass plant’s long roots, which grow deeper than annual plants’ roots, improving soil structure and reducing erosion. Jim Richardson/National Geographic Creative
Glover pauses from his research on perennial trees to chat with Rhoda Mang’anya and her children on a her farm in the Dedza district of Malawi in Africa. Jim Richardson

To get to where he is now—as a senior sustainable farming systems research adviser at USAID—Glover worked for many years as a researcher at the Land Institute in Kansas. He understood there that the state’s perennial grasses might hold the key to keeping the soil healthy, cutting down on fertilizer use, and getting more than one harvest from a single plant.

Glover found that farming could have no effect on the agricultural environment or even be good for it. Glover, who is 48 years old, was named by Nature in 2008 as one of five “crop researchers who could change the world.”Discover told Glover about his plan to do that very thing.

Annual wheatgrass root growth (shown on the left side of each column) cannot compete with better-established, more robust roots of a perennial variety, which may be the future of farming. The Land Institute
Glover stands in a soil pit to compare exposed annual and perennial root growth at the Land Institute in Kansas in 2006. Jim Richardson/National Geographic Creative

Find out: Did growing up on a farm in eastern Colorado, where it gets dry and dusty a lot, change the way you think about your job?

Hi, Jerry Glover.I was definitely affected by what was going on there. I saw the terrible damage that farming does to the land. I also saw the need and promise for farming, though. I believe it is time for us to take a serious look at how our society has grown at the cost of the soil.

What do you believe are the worst effects of traditional farming?

JG: When farmers gather their crops, they take nutrients from the soil. And some of the nutrients are lost through runoff on the farm. For example, more than half of the nitrogen that is put on wheat fields is lost before they are harvested. That loop needs to be closed. One of the best ways to do that is to make sure that the nutrients we put back into the farm stay there and are used by the plants.

A lot of farmers grow foods that need to be planted every year.

But as you did your study, you found that perennial grasses could be harvested over and over to make hay, and this could be done with little or no extra fertilizer and without taking away important nutrients like nitrogen and phosphorus from the earth.

Are food trees that grow back every year the way to feed everyone in the next few decades?

JG: It seems likely that they are. You can grow perennial plants for more than two years, either by themselves or with annuals. They can make the earth much healthier and help bacteria and fungi live together in a better community underground.

Because annuals have to grow roots all over again, their growth season is much shorter. These roots go deep, some as much as 10 feet, and will keep the plant alive for a long time. The roots can hold more rainwater down there. Those deep, well-established roots also help nutrients move around in the soil, which makes them easier for plants to use.

Of course, the best thing about perennials is that they keep the earth from washing away. If the earth is in better shape, water will soak in rather than run off. Also, perennials cover the ground with plant matter for a longer time. The leaves and twigs are there to catch the rain and lessen its effect when it comes down. That makes it less likely that the dirt will be washed away by the water.

Food crops that grow back every year, like grains like wheat and sorghum and legumes like peas and beans, are being tried out by farmers all over the world.

Why did it take so long? People should have bred perennials a long time ago if they are so great.

JG: The first people to work on plant breeding were farmers who were mostly interested in how crops would do in their first year. Because they didn’t have to worry about land or supplies, they also didn’t know about some of the bad effects of farming that we do now. There wasn’t the huge push from too many people like there is now.

Also, the tools we use to breed plants are much better now. Our computers are much stronger and faster, so we can sort through the genetic material to find the traits that will lead to more offspring. And we need to increase food production right away. It’s really a perfect storm of chance and trouble.

So, where should study and development on perennial crops go first, at least for now?

Because many poor countries need protein, I think you should start by focusing on the types of legumes that grow back every year. The best thing about legumes is that they help food systems work. For example, they can help take nitrogen out of the air and put it into the soil. Also very hopeful, and maybe soon, are types of sorghum and rice that grow back every year. The University of Georgia has been given money by my organization, USAID, to grow permanent sorghum.

Now, your main goal is to get farmers all over Africa to plant perennial foods that will feed people and keep the soil healthy. Is the land there worse than in North America?

It has always been the case that African soils were less fertile and better fit for farming than American soils. African farmers often have to deal with the tough problem of working with very old, worn-down dirt. Their soils have also been badly worn away by now. That’s where we need to make the most and quickest changes.

Where have you seen permanent plants grow well?

JG:Recently, I went to Malawi in southeastern Africa and saw a system where pigeon peas and soybeans are grown together. Pigeon peas can be grown as either an annual or permanent crop. The pigeon peas are left to grow again after the soybeans and pigeon peas are picked. People put maize in pigeon peas when they are growing back. Before this system, farmers would have grown either just maize or maize and soybeans alternately. Now, with this system, they get two harvests of legumes in one season: pigeon peas and soybeans; and then in the second season, they get a harvest of maize and pigeon peas. This means that they are really increasing the amount of protein that they grow on their farm. This is good for both their own health and the market. From my point of view as a soil scientist, it does a lot of good things for the land.

What are some things that make it hard for more African farmers to grow perennials?

JG: Pigeon peas are already used a lot, but they are usually grown only once a year. A lot more people could gain from their long-term benefits. The other crops haven’t caught on yet because there hasn’t been enough plant breeding to make perennial wheat and sorghum better enough to test on farmers’ farms.

Do you believe that perennial crops could also be important and useful in the west?

JG: I think they could be more useful in the long run than our annual grain crops because they can take in more sunlight, water, and nutrients. But in wealthy countries, there isn’t a sense of urgency. It’s likely that the political will and backing from the farm community aren’t as strong.


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