``Yes,'' says Rattan Lal, tall, thin, and intense. ``Africa does have soil that is shallow, old, low in organic matter, its nutrients washed out. ``Yes, just two inches beneath some 250 million hectares [618 million acres] of land in West Africa lies hard rock.
``Yes, tropical soils in Africa can be only eight inches deep, compared with five feet of depth in the United States.
``But . . . African land can be managed. If you disturb the topsoil as little as possible, if you mix and rotate your crops properly, and if you don't set your yield targets too high, it can be done. We've proved it.''
Dr. Lal, senior soil physicist at the International Institute of Tropical Agriculture (IITA) in Ibadan, drove me to several test plots of land to illustrate.
``True, we have less flexibility than other parts of the world,'' he said. Lal, an Indian who came to the IITA from research in Australia, has been here for 16 years. Aiming for sustainable crop yields
``Our aim is sustainable, achievable yields of food, not the maximum figures you get under perfect conditions. . . . If you learn nature's limits, you can work with her rather than against her.''
We pulled up beside two plots, side by side, on the same slope. On the left, maize (corn) grew eight feet tall, glossy green, as erect as soldiers on parade. The plot had been cleared with a bulldozer whose blade had been set at ground level. Tree stumps had been removed by hand or allowed to remain. Ground cover had been left in place and seeds punched through it into the ground in single holes with an IITA-developed rotary planter -- a spiked metal wheel at the end of a long handle.
The leguminous, treelike leucaena (pronounced ``lewcina'') plant had been mixed in so that its quick-growing, nitrogen-rich leaves would enrich the soil as they fell. The results of proper management
On the adjoining plot, maize was scraggy and thin. The land had been cleared much more quickly, with a bulldozer-driven tree pusher and root rake ripping out tree stumps, and with the blade set to tear off the top layer of soil. The next wind began blowing the soil away. The next rain washed it away. At the bottom of the slope, Lal kicked at a bare patch of red ground.
``That's hard rock,'' he said. ``Much of Ethiopia has degenerated into it. Only dynamite can help this now. . . .''
On the other side of a lake, we came to another plot that was Lal's pride and joy. He pushed into thickly packed rows of head-high maize and scooped up a handful of black soil, worm casts and all.
``See what can be done with proper management?'' he asked. First planted in 1970, this plot of 21/2 acres has produced 34 consecutive crops of maize in the Lal method: no plowing, tree stumps left in or removed by hand, mulch allowed to build up naturally, worms left to aerate the soil.
Across the dirt road, the same land had been plowed and harrowed in conventional ways. The crop was poor. The ``soil'' was reddish black, full of stones, and hard.
``The methods that I suggest are those an African farmer can follow,'' Lal said as we drove away. ``Despite all the fashionable predictions of disaster for Africa, and despite Ethiopia, I believe that a food revolution is coming here. . . .''
Better soil management must be accompanied by higher prices for farmers, he said, to encourage them to grow and sell food.
But soil degradation is not inevitable, Lal insists. ``If we can get the word out to the farmers,'' he said as we parted, ``they can achieve not maximum, but solid, repeatable yields on the land they have. It's a question of management, you see.''