Food for thought

摘要

Chemical fertilizers get a bad press, with some justification. Their use can pollute water supplies and generate significant greenhouse-gas emissions. But they are an excellent way to boost crop yields: they help to grow food. And in sub-Saharan Africa that means they can help to fill empty bellies and save lives. Parts of Africa sorely need that help. Across the continent, agricultural lands are characterized by red soil that is low in nutrients. Intensive farming has seen the typical hectare of sub-Saharan farmland lose 22 kilograms of nitrogen, 2.5 kg of phosphorus and 15 kg of potassium annually over the past 30 years.