Hedgerow farming. In alley cropping, a form of agroforestry, farmers plant rows of trees close together, leaving 5 to 10 times the hedgerow width between the rows for crops or pasture.
RAYMOND ROWE works out of an office in Washington, just a short stroll from the Potomac. But the Welsh-born, one-time rugby star and agroforestry expert with the World Bank wears a tan he has picked up in a dozen far-flung regions of the globe. For something like one-third of each year he's in places like Indonesia, Malaysia, several West African states, and some in Latin America - wherever tropical forests are falling in the face of exploding populations.Skip to next paragraph
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He's not there to stop the felling but to promote a compromise, something that offers hope to people who face a quite desperate future as soil fertility disappears with the dwindling trees. He calls the compromise alley cropping. It's a land-use system that promises to break the farm-today, abandon-tomorrow cycle common to these regions.
Mr. Rowe is quick to stress the difference between forest destruction taking place in some parts of the Western Hemisphere to produce cheap beef for the American hamburger market, and tree cutting in regions where he is working. ``I'm not talking about optional clearing, but inevitable clearing,'' he says, ``regions where trees are disappearing because people are running out of places to live.'' Indonesia is the prime example, but there are many others.
Clearing the forest is only a temporary solution to the need for land. Within five years the fertility is gone and the exhausted soils are abandoned in favor of yet more clearing. Tropical soils are fragile at best and erosion becomes widespread. Even in regions of moderate rainfall, the desert's advance becomes inevitable.
In Indonesia, erosion is less threatening, but the result is only marginally better. Abandoned land in that crowded nation is overtaken by a grass that prevents natural reforestation and creates a fire-prone environment. And while it has some use as a thatching material, it is unpalatable to grazing animals. In effect, a desert of sand is replaced by a desert of grass.
Worldwide the situation is critical, because 11 million hectares (27 million acres) of tropical forest disappear every year. That's the equivalent of converting Minnesota into a treeless plain in less than two years.
Increasingly, agroforestry is being seen as a practical and ecologically acceptable answer to the problem. Alley cropping is a specialized form of agroforestry.
It involves planting two to four rows of leguminous (nitrogen-fixing) trees on two-foot centers, so they become a hedge leaving 5 to 10 times the hedgerow width for crops or pasture, then more trees and so on, until the area to be farmed is covered in this way.
The result is a series of oblong fields or alleys, protected on each side by the hedgerows. On sloping ground, the trees can be planted on the sides of the terraces, leaving the flat area in between for cultivation. A variation on the theme is to create a series of hedgerow-protected squares.
Stabilize the fragile soils, arresting both wind and water erosion.
Fix air-borne nitrogen in the soil, because they are legumes and draw up nutrients too deep for the shallower-rooted crops.
Fertilize and add much-needed organic matter to the soil when the clippings are spread on the cultivated alleys. Alternatively, the clippings become fodder for livestock and the manure is spread on the soil.
Provide a refuge for birds, which control insect pests.