At the recent African Green Revolution Forum (AGRF) in Arusha, Tanzania, fertilizer was a hot topic. Government leaders, policy makers, NGOs and businessmen and women in freshly pressed suits extolled the merits of, well, dirt. But for millions of smallholder farmers across Africa, soil quality can mean the difference between a full harvest or a failed crop.

And for Gary Toenniessen, managing director of the Rockefeller Foundation, making sure farmers get fertilizer at a reasonable price is a major challenge. The foundation, a funder and founding partner of the Alliance for a Green Revolution in Africa (AGRA), has been a key supporter of small-scale growers across the continent and ensuring that supply chains, like those for fertilizer, actually reach them.

AllAfrica's Lauren Everitt caught up with Toenniessen to uncover just what it takes to bring success to some of Africa's poorest producers. Toenniessen, who oversees the foundation's work related to agriculture, is optimistic that the African sector is headed toward a model that generates sustainable incomes for farmers. More leaders are seeing it as an "engine for economic development", rather than a "donor-led development project", he says.

As far as challenges in agricultural development, are there issues that appeared in 2006, when AGRA was formed, that you're still contending with today?

One of the main ones is getting fertilizer to farmers at a reasonable price. Just about the time that AGRA was being established, the Rockefeller Foundation funded the Africa Fertilizer Summit in Abuja in 2006. At that summit there were several presidents from African countries, and they pledged that they were going to increase fertilizer use to 50kg/hectare. I think at that time it was something like 8kg/hectare and maybe now it's 10kg/hectare, but it varies from country to country.

One of things that we heard at AGRF is the creation of an Africa Fertilizer and Agribusiness Partnership. That's a new institutional innovation, which is really designed to come up with other innovations: technical innovations, market innovations and policy innovations. Those innovations will build that fertilizer supply chain from production to blending to packaging to markets, and hopefully increase efficiencies sufficiently to do that at a lower price than what Africa's farmers currently have to pay.

Were there any key takeaways for you from the African Green Revolution Forum?

I was really impressed with the degree to which the president of Tanzania understands agriculture. A lot of the things that I was going to say, he said. And we've heard commitments from a number of these ministers. The minister of agriculture from Nigeria said, 'We can't let agriculture be a donor-led development project. We need to make it into a business that's generating income for farmers and the country.' It's not a development project. Agriculture is a business, so you're beginning to see that change in attitude from African leaders, looking at agriculture as an engine for economic development rather than a sector that the government has to fund and get donors to fund.

Have there been any false starts or times when the Rockefeller Foundation had to change course to pursue a different strategy?

I don't think there's been a change of course but with a lot of these initiatives it doesn't work as well as you wanted it to. So you may have a useful innovation but it doesn't reach as many small-scale farmers as you want it to, so you then need to go back and tweak it and come up with new innovation or a modification.

Credit guarantees are a good example of that. Credit guarantees have been quite successful in getting banks to invest in agricultural value chains, but they haven't invested anywhere near to the degree that we would like to see them invest in small-scale farmers directly. They still view those farmers as too risky. Under rain-fed agriculture it is a risky business. So there's probably a role there for a public-private partnership where the public sector can come in and somehow reduce that risk for the private sector, such as through a weather-index crop insurance scheme or something like that. So we're already investing in pilots that are looking at those types of schemes - a new innovation that is added onto something that could work better than it currently is.

Friends of the Earth has called AGRA the "Trojan horse" of biotechnology and says it serves the interests of biotechnology multinationals. What is your response?

The degree to which AGRA should be engaged in biotechnology has been discussed by the AGRA board and by the donors of AGRA from the beginning. The decision was made that at this stage AGRA should not invest in biotechnology because there's so much that still can be gained through conventional breeding and other techniques, and that technology – conventional breeding – needs to be developed first.

Now if that's a Trojan horse so that in 20 years biotechnology can benefit African agriculture, I actually think that's a good thing. But the reality is that AGRA is not investing in biotechnology.  Both the Gates Foundation and the Rockefeller Foundation have invested in biotechnology.  AGRA is not opposed to biotechnology; it just believes that it's wiser at this stage to invest in building the conventional plant breeding capacity because you need that in order for biotechnology to have any value. Biotechnology does not produce improved varieties by itself. It's just a new tool that you can add onto a strong conventional breeding program.

So what Africa needs first are strong conventional breeding programs, and then maybe down the line African countries can make their own decisions on whether they want to use biotechnology or not. And it shouldn't be either Friends of the Earth or the Rockefeller Foundation that tell them what to do. It's like the [Nigerian] minister [of agriculture] said this morning, we need to run this show and make it into a business. So they can decide.

Friends of the Earth also criticised AGRA's approach to sustainable agriculture. How do you counter criticism that increasing chemical fertilizer and pesticide use, as well as the use of genetically modified seeds, is not a sustainable solution?

Let me first correct the term you used – and that's genetically modified seeds. Yes, AGRA does do conventional genetic modification, or breeding. It doesn't do genetic engineering. But it does produce genetically improved varieties through conventional plant breeding.

I think it's a misguided argument. In my opinion, the most important environmental problem in Africa today is the depletion of soil fertility, and that's due to the fact that the nutrients are being taken out of the soil by the crops and they're not being replenished. I think it was the president of Tanzania who said we're using 8kg/hectare and the Dutch are using 500kg/hectare and telling us we shouldn't use fertilizer.

Every other major agricultural region of the world utilizes fertilizer, and I think Africa needs to use fertilizer and it needs to use it wisely, it needs to use it judiciously. Yes, you can overuse fertilizer, too. And that is happening in some countries. But Africa is a long way from overusing. So if Africa were using 50 kg/hectare, as was recommended at the Abuja summit, that would go a long a ways toward improving soil fertility. And it would cause almost no environmental problems because the crops would absorb that much of the nutrients and there wouldn't really be any surplus runoff or other problems associated with fertilizer use. Basically you're taking off what you're putting in.

Is there anything else that you would like to add?

One thing that has struck me recently is the need to increase labor productivity on Africa's farms. In most of agriculture traditionally, there has been tremendous labor inefficiency due to the seasonality of production. So during the growing season, the farmers really work hard – they have more jobs than they can do. But during the dry, non-growing season they're often under-employed. Lots of times they're working, but they're not doing work that is productive in leading to income. I think we need to try to find ways to spread the productive work year longer.

If you go back to the Green Revolution in Asia, one of the big successes there was short duration varieties, which allowed double cropping and triple cropping so that the farmers could get two crops a year and even in some cases, where they had irrigation, three crops a year.

So they were able to work many more days of the year productively, producing grain than they had previously under the old one crop per year system. And that's pretty much what you still have in Africa is one crop per year. One of the obvious ways of doing that is through small-scale irrigation, but I think there are other ways too. You might be able to grow two-short season crops, for example.

In order to spread the workload out, you'd grow crops in sequence. So you might grow a short-duration maize crop.  So let's say you had half a year of rainfall – so 160 days – well you could get a maize crop in 100 days. You don't get as much yield as you would with a variety that takes 150 days but you still have a good crop. And if you can get a second crop, say you have a cassava crop, and you get 50 days of that and then harvest it at the end of the dry season. I'm not sure exactly what the sequence would be, but the idea is to help the farmers to have productive, on-farm work for more days of the year. It might not even be crop production. It may be packaging and processing on the farm.

Just taking a rice crop and increasing the quality of the rice by taking stones out or something like that would lead to an increase in income. It might take an additional 20 days after the harvest or something like that, but that's productive work, and that's how you increase the income of people, by having them engaged in more days of productive work.

Tanzanian President Jakaya Kikwete said at AGRF that 2,000 years ago people were using hoes and yet many farmers in Africa are still using them. Do you see a point when more African farmers will be using tractors and mechanized equipment – is that in the foreseeable future?

I'm not sure it's going to be a big tractor, in the sense of what we would see in Europe or North America. But I think that mechanized equipment like you see in India or China or other countries where small-scale farmers are highly productive, yes, I do think you may begin to see that.

One of our grantees, Kickstart, offers hip pumps, but even they say the farmers might grow to a gasoline-powered pump, as well. So that kind of mechanization you can expect to see. I don't think you want the same thing to happen in Africa that happened in Latin America, where you had these large aggregations.

Part of AGRA's mission is to help the smallholder farmer scale up. But is there a threshold level where the farms become too big and we see a repeat of what's happening in Latin America?

I think you want to follow the Asian model as opposed to the Latin American one – so encourage increases in small-scale production as opposed to increasing large scale production.  Both of them are quite successful in increasing food production, but in Latin America it led most of the poor people moving into the cities so Latin America is a very urban region. Whereas in Asia the rural sectors really became a center of economic growth through small-scale farming.