Rising food demands need to be satisfied by existing farm lands | Connect Asia

Rising food demands need to be satisfied by existing farm lands

Rising food demands need to be satisfied by existing farm lands

Posted 26 July 2011, 16:48 AEST

Scientists and policy makers face the challenge of the need to double the world's food production by 2050 in order to cope with a global population which will have reached more than nine billion by that date.

The question for many is how to do that without converting our forests, wetlands and grass lands to agricultural land.

Presenter:Bill Bainbridge

Speaker: Professor Kenneth Cassman, from the University of Nebraska is Melbourne for the current International Botanical Congress.

CASSMAN: The additional food has to come from existing farmland, and I say that because of a number of reasons, first, we really want to protect the last remaining natural ecosytems. You mentioned the rainforests, the wetlands, the grassland savannahs, and there's two reasons for that. The first is they are a bastion for biodiversity, so if you are concerned about the Sumatran tiger, the orangutan, the African elephant, the key is holding agriculture to its existing cropland. These animals need large areas to be viable in terms of their natural populations. The second is, that those areas are also very carbon rich. So if you think of a rainforest; huge vast quantities of carbon are stored in both the above ground biomass, and the below ground soil organic matter. When you convert them to agriculture you lose a tremendous amount of carbon dioxide into the atmosphere, which contributes markedly to the burden of greenhouse gas emissions. So looking forward I think we need an explicit goal as humans on this planet that we must find a way to meet this doubling or so of food demand on existing farmland, and I'm just not sure the magnitude of that scientific challenge has weighed in on policy makers and those that can change the trajectory of history.

BAINBRIDGE: Ok we're trying to protect the forests from encroaching farmland, but what about protecting the farmland from encroaching other activities; rapid urbanisation, suburbanisation, in Vietnam for instance a lot of productive rice-growing farmland is being turned into golf courses and resorts?

CASSMAN: Well and let's not exclude Melbourne, Brisbane and Sydney, and let's not exclude Chicago, Los Angeles, New York, I mean this is a global phenomenon isn't it? And the irony is, Bill. that why were cities located where they are today? Well it's because hundred, five-hundred, a thousand years ago when all the world's major cities were established, it wasn't possible to move food large distances. So major cities had to be located on the best soils. So it's even a bit more challenging than you say that the expansion of urban areas today is occurring on our best farmland and if we replace it can only be with ever more marginal land that's more difficult to produce crops. So again even a larger challenge. Having said that, it's only to my mind extremely exciting because we can do it if we see clearly the magnitude of the challenge. Now having said that we're not on track to do it because it's only recently I think that we've become aware of how large this challenge is.

BAINBRIDGE: And one aspect of that challenge is that as we're seeing India and China get richer and get richer, their diet changes, they move from eating a lot of grains to eating meat, which takes a lot of grain, a lot of water to produce. Can we really afford for places like China and India to become wealthy and therefore start consuming meat, is that an affordable scenario going forward to 2050?

CASSMAN: I don't think we should look at it that way. It's inevitable, that is that large populations that have been essentially deprived of access to more diverse diets, diets that allow their children to grow taller, to have greater cognitive abilities, greater physical skills. They're probably going to overshoot on the consumption of these products, that's just human nature. And anyone that suggests that we have a strategy for the future about how to feed a global population, nine-point-five billion, that depends on a large modification of what humans eat at various income levels in developing countries like China and India I think it's like an ostrich with their head in the sand. I think what we need to do is assume that human nature continues as it has and that countries as they get wealthy from being very low income countries with an ability to eat only the very most rudimentary diet, they're likely to overshoot. And so our global plan plan must include an ability to provision this wealthier population that's going to be above nine-billion.

BAINBRIDGE: And so what about the impact of bio-fuels, we've covered this a lot on the program, there's been a very well-meaning surge in production of fuels from plants as a way to address climate change, but with so many mouths to feed, which surely is the primary purpose of growing food, has this been just a huge mis-allocation of resources?

CASSMAN: I'm most familiar with the United States and the policies with regard to using maize for bio-ethanol. When those policies were put in place the problem was there was too much maize, and the price was so low, you're a young man Bill but in the 1980s many of our farmers went out of business and it's so very sad, they lost their farms because the price of maize and soy beans were so low that it became a government priority to find ways to add value to these crops, to save rural America. I bet you had similar policies here in Australia in different ways, not with bio-fuels but in preserving income and opportunity in rural Australia. And so now you're saying that yeah, now that we have a different world should they change? And obviously they should. But let me say that even without any subsidies, any government support for turning maize into ethanol, it all depends on the price of petroleum, because there is a price of petroleum where the best use of maize for whomever buys it is to make bio-fuels.

BAINBRIDGE: We are making breakthroughs all the time. Just the other day we had a researcher on who identified the genes that cause chalkiness in rice, something which she said could increase the value of a rice crop by about 25 per cent if that set of genes could be bred out. Can we put our faith in these kind of advances to help grow more food on the same land?

CASSMAN: Well that's an excellent example because what you're talking about are single genes or two or three genes, but rather simple systems that effect one property of a plant. So chalkiness in rice for example, or diseases for instance. Many diseases can be reduced in severity by changing one gene that converts resistance or tolerance of some kind. But what you're talking about is different, you're talking about genetic opportunities that can increase yield in the fact of let's say water limitation or even on irrigated land, just the ultimate ceiling of yield that you get under optimal conditions. And the challenge here is that there are hundreds of genes involved, those that we call complex traits. Now the bad news is we haven't been very good yet at using the new tools for bio-technology to make significant impact on those complex traits. The good news is that with enough funding and with understanding the magnitude of the challenge and government support for some of these things, because you can ask why the private sector doesn't step in well many of these things are long-term, they won't show up on a quarterly report. It takes government support in there for the long term. I have every confidence that we can meet this challenge, but we have to understand how large the scientific challenge is.

BAINBRIDGE: And does that mean genetically modified crops, because some people are terrified of the idea of genetically modified crops?

CASSMAN: I think it means all tools in our tool chest of which trans-genic crops we'll call them. I mean any time you cross two lines of rice genetically modified from my view, genetically modified is a complete misnomer, but let's call them trans-genics, that is you take a gene from one organism and stick it in another, a trans-gene. Yes I think it's going to be an important tool, it's not a panacea and there has to be important controls and testing safety environments and so forth, but there's no question Bill that that must be a component of our tool box.

BAINBRIDGE: And so can you tell me what is the genetic yield ceiling, this is something that your working on, a phrase I hadn't heard before?

CASSMAN: Well that's right, any time you take a seed in your hand and you plant it in the ground, that seed, that plant has a limit on its yield that's determined by the amount of sunlight it's going to see, the temperature that tells you how long it grows for, so how much time it can capture sunlight, and the amount of water it has access to. At the most rudimentary level that's what determines the yield ceiling. And the point is that in many parts of the world now it looks as though average farm yields are starting to run up against that genetic ceiling, and so we're seeing a plateauing of yield. And what we're interested in is understanding how to predict where that occurs, and you can only do that by having what we're saying is a global yield gap atlas that looks at the difference between that genetic yield potential and where average farm yields are today.

BAINBRIDGE: And so that would be a tool that farmers themselves would use in order to understand how much greater their yield could be from a particular crop?

CASSMAN: That's one use, so at the farm level it's a bit like I talk to farmers in this way, have you ever been a very clear body of water whether it's off the Great Barrier Reef or in a lake and you're down about three metres and looking to the surface, it's very difficult to tell how far away you are from that shimmering surface. You could be ten metres or three metres. Well that's problematic if you're running out of breath. Same with managing a crop, if you don't know where you are relative to that yield ceiling, you really don't know how much further you can push yields and whether it's profitable to do so. So I think it's an incredible benchmark for producers, but also if you look globally, if we could do that on every hectare of land, we could identify where the greatest yield gaps are and begin focussing our research, resources to those areas that have the greatest potential to close that gap.

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