What do you need to create a green revolution in Africa? Women and fertilizer Walk through countless¹ small villages in sub-Saharan Africa, and you will find the same scene repeated again and again: women bent² over double, hoeing scrawny（骨瘦如柴的） plants in dirt packed so hard it's tough to imagine anything ever growing in it. Hundreds of billions of dollars have been spent over the past half-century trying to do something about the region's crushing poverty, but the situation remains³ desperate. Rural Africa is hollowing out, unable to feed itself, let alone supply food to the continent's rapidly growing megacities（大城市） .

In this context, the Gates and Rockefeller foundations announced last week their plan to spend $150 million over the next five years to boost agricultural productivity on the continent. The initial investments will go to developing hardy⁴ seed varieties of regionally appropriate crops, creating markets for the distribution of those seeds and educating a new generation of African plant scientists. It's a back-to-basics approach that avoids gambling⁵ on shortcuts⁶. But to be successful the new initiative--dubbed（被称为） the Alliance for a Green Revolution in Africa--will very soon have to address two equally pressing issues: the need for widespread use of chemical fertilizers to replenish⁷（补充） exhausted⁸ soil and some sort of system to ensure greater participation⁹ of women--who perform the bulk of the work on Africa's farms.

Action is urgently needed. More than 80% of African soil is seriously degraded, and in many areas it is on the verge¹⁰ of permanent failure. For centuries, farmers survived by clearing new land for each season's plantings and allowing old fields to lie fallow and replenish their nutrients¹¹. But the continent's fourfold increase in population since the 1950s has forced farmers to grow crop after crop on the same fields, draining them of all nourishment¹². Do that for a long enough time, and the physical nature of the soil changes. It becomes so tightly compacted that it can't hold water or let roots spread. "Eventually you get to the point where even weeds won't grow," says Gary Toenniessen, director of food security at the Rockefeller Foundation. "Just adding fertilizer back doesn't help. You actually have to replace the soil." The loss of productive land has driven farmers to clear ever more marginal（边缘的） areas, including forests and hillsides, for agriculture.

Fertilizer has a bad reputation among environmentalists in the West because pollution from runoff can be such a problem. But replenishing Africa's soil before it's too late--and thus decreasing the amount of land that has to be dedicated¹³ to agriculture--is probably one of the most practical ways of protecting wildlife habitats and reducing erosion. And new micro-dosing techniques, in which a capful of fertilizer is applied¹⁴ to the roots of a plant, minimize the flow of chemicals into rivers and streams.

Many African countries that used to subsidize fertilizers stopped under pressure from the World Bank and the International Monetary¹⁵ Fund, forcing farmers to return to subsistence practices. Today farmers in sub-Saharan Africa use about 7 lbs. of fertilizer per acre, compared with 75 lbs. in South America, 87 lbs. in North America and 91 lbs. in South Asia.