Kai Ryssdal: We've been working on a big population and food project for the past half year or so geared around this question: With the United Nations saying there are gonna be 9 billion people on the planet by the middle of the century, how are we gonna feed them all? In Africa right now, a continent with one of the world's fastest growing populations, a lot of farmers work the same way their ancestors did -- no fertilizers or improved seeds. No fancy machinery or sophisticated irrigation systems. And yet they're going to have to double the amount of food they produce by 2050.
Today on our series Food for 9 Billion, Jori Lewis went to Ghana to find out how they might do that.
Jori Lewis: For farmers, it all comes down to the dirt. I've come to Kumasi, in central Ghana, to visit the Soil Research Institute. Ghana sits due south of Spain, Morocco and Mali, and right now, is West Africa's superstar. After discovering some 3 billion barrels of oil in 2007, Ghana's economy went into overdrive. In 2011, it was the world's fastest-growing economy.
It has one of the fastest-growing populations too -- more than 20 million now. Kumasi is in the Ashanti region, where rolling hills and forests support corn and yam, cocoa and coffee. In the years to come, these hills will need to produce more than ever before.
Dr. Francis Tetteh from the Soil Research Institute is standing on the side of one of those hills now, showing me a deep pit. He's uncovering the secrets of the dirt itself.
Francis Tetteh: There are two kinds of soils in the whole of the Ashanti region. This area, you see here, has the two groups coming together.
He says that for thousands of years subsistence farmers have been taking nutrients out of the soil and not putting them back. In effect, farmers are mining the soil. And this is the problem all over Africa: the nutrients are gone and the soil can't produce.
Not far from the Soil Research Institute, I find the tiny village of Fufuo. It's a town full of red dirt and red buildings. Farmers here traditionally practiced "shifting cultivation" -- meaning they clear the forest, farm 'til the dirt is exhausted and then move on.
In the 1980s, a development project brought things farmers had never had before: improved corn seeds, fertilizers and herbicides. This changed everything -- bigger corn, bigger harvests and more money. But once that project ended, farmers still couldn't afford fertilizers on their own. Even today with the Ghanaian government subsidizing fertilizer prices, the cost is still too much.
Agronomist Kofi Boa said that fertilizer is sometimes necessary, but not always. What farmers need are better ways to manage the soil. Boa is a devotee of what's called "no-till" farming, where farmers simply leave all the unused parts of crops to decompose on the field. That makes a mulch that keeps moisture in and adds back nutrients. The soil stays covered and is restored by nature.
Kofi Boa: You see here, you can really sense life. Unlike here, you don't see anything here. But when you come here, wherever you have the mulch. You see this one? This is telling you there is an activity.
But no-till has a downside: weeds like you wouldn't believe. Enter agrochemical company Monsanto. It sells farmers an herbicide to kill those weeds -- an herbicide called glyphosate, better known as Roundup.
On the road we pass men in protective boots and gloves with chemical cans on their backs and sprayers in their hands. Boa says the secret to no-till farming's adoption in Ghana was actually glyphosate. And that eventually, the product took over.
Boa: Having the glyphosate available meant that farmers could just have it easy. If the whole thing is just about killing weeds and not caring about having a mulch, then it defeats the purpose of whatever we set out to do.
Boa says no-till systems also need cover crops to prevent erosion and other plants to deliver more nutrients to the soil. But all that has been a harder sell to Ghanaian farmers than glyphosate and fertilizer. After all, why let the dirt rest and recharge when chemicals can help it produce without interruption?
Across the country, in the northern regions of Ghana, small farmers are looking for different solutions because they want and need to. In the north, the savannah stretches out dry and flat. And the rains come just once a year. Farmers can't afford a lot of fertilizers, herbicides and improved seeds, so they manage their entire farms -- from water to waste streams -- and make use of everything.
In a northern Dagomba village, I meet farmer Richard Dahaman. He invites me to share a typical midday meal -- rice and a sauce made from peanut butter. Dahaman shows me around his house and fields. He shows me his rainwater tank where his 30 sheep sleep, and where he collects the sheep droppings, which allow him to cut back on fertilizer. And best of all, it's working for him. He said that before, he wasn't doing much and wasn't making much money either.
Richard Dahaman: I was alone, a bachelor. Even the money I was getting wasn't enough for me. And now, I have a family.
Now, his yields and his money have increased. He's sending his children to school and adding on to his house. But Kofi Boa says this practice takes a lot of work. And it will never be as easy as simply buying fertilizer and glyphosate. And as farmers are more successful, there's no way to keep them from switching to what's easy.
Boa: For me, I surely would want to see every African government paying a lot of attention to sustainable cropping systems. People should not just pay lip service because it's mandatory for them to talk about it, governments have to be committed.
He dreams of a day governments will subsidize compost as well as fertilizer; when enterprising farmers plant cover crops to go along with their hybrid corn; when people recognize that to feed as many as we're gong to need to, soil matters. Just as much as the crop.
In Ghana, I'm Jori Lewis for Marketplace.