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Food for thought

In the short term, chemical fertilizers are the best way to feed Africa.

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 22kilograms of nitrogen, 2.5 kg of phosphorus and 15 kg of potassium annually over the past 30 years. Impoverished African farmers cannot afford to wait for the international community to deliberate on the long-term, green methods needed for a sustainable global agricultural system. They need to deploy methods that work now — and that means that in the short term, they need access to chemical fertilizers.

But there lies the problem. Most of the Malawian farmers interviewed for the Feature on page 525, for example, said that their biggest problem is the high cost and poor supply of fertilizer.

Although this evidence is anecdotal, it hints at something more. Farming a smallholding is intensive, backbreaking work that, for the most part, is done out of necessity, not choice. Greener practices such as no-till farming may be cheaper than using fertilizer, but they are less efficient and lack appeal because they add to farmers' already hard labour. By contrast, the quick and easy gains of fertilizers free up farmers' time, and can turn a subsistence existence into a commercial operation, offering a potential way to escape the crushing cycle of poverty.

Africa is not a laboratory in which to investigate and promote alternative agricultural strategies at the expense of those that are known to work. Development efforts need instead to focus first on the problems of fertilizer supply and cost. Without fertilizers, it is hard to see how African farmers can catch up with their counterparts in Europe, North America and Asia, all of whom benefited from the boost chemicals gave their agricultural enterprise.

Subsidies are a key way to tackle this problem. It is encouraging that economists, including some at the World Bank, are recognizing that subsidies can help private-sector development, as demonstrated by Rwanda's agriculture-support programme, which meets some of the costs of fertilizer transport. Still, last week's coup d'état in Mali is a worrisome reminder of the political volatility in some parts of the continent, which can make donors reluctant to inject more cash because they fear that it will not reach its intended target.

There are other financial tools, too. Kenya's Equity Bank, for example, set up a loan system in 2008 to help farmers buy fertilizer. It lends the farmers cash at the start of the agricultural season, when they need fertilizer most but are least able to afford it, and allows them to pay back the loan at harvest time, when they sell their crop.

Improved access to fertilizer, although essential at present, is not the best long-term solution. Research must continue to reduce reliance on chemicals and to make their use more efficient. As highlighted on page 525, accurate and detailed information being gathered on soil types and health can allow for more precise and appropriate fertilizer application. Work is also needed to reduce the thirst of crops for fertilizer, and further improvements could be made by manipulating the soil and microorganisms around plant roots to increase the amount of dissolved nitrogen available to the crops.

Ultimately, the move towards a more sustainable form of agriculture will require investment to help farmers in Africa take advantage of alternatives to chemical fertilizers, although they will need to be convinced of the benefits of these new approaches.

The key to success is for farmers to choose the practices that will work best for them — past development efforts have shown that without buy-in from local communities, initiatives simply don't work. For now, that has to mean improved access to fertilizers, because the choice between food and famine is an easy one.

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Food for thought. Nature 483, 510 (2012).

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