Combatting Desertification and Drought with Crop Diversity
Luigi Guarino | Director of Science
They say that if the only tool you have is a hammer, all your problems look like nails. Well, I work with genebanks, so it’s natural for me to think that most problems can be solved by crop diversity.
Take, for example, the report the International Panel on Climate Change (IPCC) has just released on Climate Change and Land. It’s an in-depth study of “desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems.” It makes for sobering reading. Some takes in the media have been downright apocalyptic. Deutsche Welle, for example, had this headline: “The world gets hungrier, but the land is exhausted – from us and from climate change.”
But that doesn’t mean there’s nothing that can be done.
Before discussing what that might be, though, let’s first agree that how we use land does in fact impact the rate of climate change. It’s not just about cutting down on burning fossil fuels. Approximately a quarter of the CO2 released into the atmosphere comes from how we use – or misuse – land, including to grow food. The main culprits are: deforestation, especially in the tropics; methane emissions, from burping ruminants and rice fields; and nitrous oxide emissions, caused by the overuse of fertilizers on crops.
What can be done? Well, there are some changes to the food system as a whole that would certainly help a lot, in particular reducing waste and eating a bit less beef. Hence the common take-away message from the IPCC report enshrined in the BBC’s headline: “Plant-based diet can fight climate change.”
But let’s consider deforestation and greenhouse gas emissions a bit more closely. It might just be the hammer in my hands, but those do look a lot like nails to me.
It’s a complicated issue, of course, but higher yields from agricultural land might take some of the steam out of agricultural expansion into forest lands, and higher yields come at least in part from better crop varieties.
New forage and pasture plants and rice varieties could also contribute to reducing methane emissions. Take rice. IRRI has a website listing all kinds of technologies that could help cut down greenhouse gas emissions from rice cultivation. Most are agronomic tweaks. But their adoption and success require varieties that are adapted to the new practices.
Next, new crops and varieties which use fertilizer more efficiently would help with the nitrous oxide problem. A recent review was clear about the potential: “Significant but limited variation [in nitrogen use efficiency] exists in modern germplasm pools; however, a huge opportunity exists to exploit more diverse germplasm collections...”
New, better, climate-smarter varieties are impossible without breeders having access to the genetic diversity of crops. It’s their raw material: the breeding pipeline starts in the genebank.
There are more nails, though. Because it’s not just about reducing greenhouse gases. Another path to more sustainable, climate-friendly land use is locking up more carbon. That means restoring forests, sure, but also planting more trees on farmland – agroforestry. And that’s just one of the sorts of farming practices that could increase the ability of agricultural land to store carbon. Others include no-till agriculture, planting perennial crops, and agroecology.
A recent study by the Union of Concerned Scientists, for example, listed a number of things farmers growing the ingredients of breakfast cereals are doing to “reverse soil damage, improve water quality, and … adapt to and mitigate climate change.” The study recommended that companies that source such ingredients adopt purchasing policies in support of these practices.
But again, you need crop diversity to make any of that work efficiently and effectively.
Finally, even varieties of crops like beans and rice which cook faster might play their part, reducing the use of both fuelwood and fossil fuels.
And all this is only on the mitigation side of things. The fact is, climate change is with us already, and we need to adapt, as well as minimize the future damage we will do. And, guess what? Adapting crops to new climates also requires that breeders continue to have access to the crop diversity in genebanks.
Yes, if you’re holding a hammer, all your problems may indeed look like nails. But, sometimes, you might actually be right.