Climate change is threatening to complicate the lives of smallholder farmers throughout the developing world. The ultimate solution to the root causes of human-driven global warming is to drastically lower greenhouse gas emissions. But this goal eludes us, unfortunately.
That means farms will have to adapt, and agricultural innovators must help them prepare for the challenges that rising temperatures will deliver.
The greatest concern is drought and dry spells. Models show that arid farming regions will likely become drier as average temperatures increase. Stronger and longer droughts may make some crops unable to grow even in places where they are commonly cultivated now. Farms can adapt by embracing more drought-tolerant crops, like the Bambara groundnut. Another solution is to develop more drought-tolerant or drought-resistant varieties of existing crops, like newer and improved maize that grows with less water.
What about some equally serious but lesser-known risks to agriculture posed by climate change, like saltwater intrusions, heat stress, and changing disease and pest patterns? There are potential solutions to these problems, as well.
As Grow Further rolls out more grant support to agricultural research and development we are keeping several potential climate-related solutions for smallholder agriculture on our radar.
A solution to saltwater
Sea level rise threatens coastal regions nearly everywhere. Coastal farms will feel the impact as well. Higher seas mean worse storm surge during typhoons, especially at high tide. A more pernicious problem is saltwater intrusion, with ever-rising seas gradually seeping into groundwater and adding salinity to soil moisture and the soil itself. Most terrestrial plants don’t tolerate salty environments very well. However, there are exceptions, and science is now exploring ways to harness the tricks salt-tolerant plants use to help crops adapt to similar conditions.
Mangrove forests are made up of terrestrial trees adapted to grow along ocean coastlines. They are among the most important ecosystems on Earth. Mangroves help prevent coastal erosion and even build land. The buttress-like structures formed by mangrove tree root systems serve as nurseries for fish species. And mangroves famously protect coastal communities from storm surge. Now, agricultural innovators are exploring ways to borrow the evolutionary tricks of mangrove trees to help crops withstand rising salinity.
Mangroves grow out into the ocean but don’t draw their sustenance from seawater. Rather, their deep root systems bypass the salt water to tap fresher reserves underground. Mangrove trees have also adapted a way to leach salt from their roots.
Mangrove trees also disburse their seeds via the ocean, and these seeds are remarkably resilient to saltwater. One way they’ve achieved this resilience is through specialized bacteria. This gave a team of Italian researchers an idea.
“Our hypothesis was that mangroves, being able to grow into seawater, should harbor bacteria able to interact with the host and to exert positive effects under salt stress, which could be exploited to improve crop production,” they explained in their study. These researchers isolated more than 100 different types of bacteria and identified the “12 most promising isolates” that they believed helped mangroves overcome salinity to grow stronger roots and bigger, tougher seeds. Explaining their experiment in a paper published in Microbiological Research, they said they then applied these beneficial bacteria to test plots of barley and rice.
The results? 65 percent heavier barley ears and 62 percent greater biomass in salt-stressed rice plants. Needless to say, the team was impressed. “We demonstrated that propagules, the reproductive units of mangroves, host beneficial bacteria that enhance the potential of mangrove seedlings establishment and confer salt tolerance to cereal crops,” the team concluded.
More experimentation is in order. But this study shows that saltwater intrusion, while a danger, does not necessarily mean the end of coastal smallholder farming. One answer may be to learn how salt-tough plants handle ocean water and then find innovative ways to give farmers’ crops these same traits. Another solution being considered involves treating soils contaminated by seawater with gypsum as a way to help crops cope with salt stress.
Beating the heat stress
Worldwide, average daily temperatures are rising as greenhouse gases continue to accumulate in the atmosphere. Nighttime temperatures are rising even faster. The heat is punishing people, animals, and plants during the daytime. Meanwhile, crops that rely on cooler nighttime temperatures to recover and increasingly unable to do so. Some studies suggest that higher nighttime temperatures could be causing lower rice yields in Southeast Asia.
Scientists have proposed a few potential solutions to heat stress. Some say the solution is crop migration—crops that are less tolerant to the heat stress should be shifted to more temperate latitudes, they say, with heat-resistant crops replacing them closer to the equator. This may be easier said than done.
A simpler solution could be irrigation. Watering crops during the day or night should help cool them down and improve their ability to take the summer heat in stride. Unfortunately, most smallholder farms are rain-fed and the farmers generally can’t afford to add irrigation.
Scientists are also exploring ways to develop varieties of existing crops that can handle heat stress better.
Research from 2007 proposed investigating the genetic and molecular processes at work that allow some plants to tolerate higher temperatures better than others. Pearl millet is a good example.
This cereal is known to be among the most heat-tolerant crops farmers can grow. Innovative labs could potentially unlock the secret behind pearl millet’s toughness and devise ways to give other crops this strength. Or, farmers could simply swap out heat-sensitive crops like wheat or rice with pearl millet. “Of all the major cereal crops, pearl millet is most tolerant of extreme temperatures and drought,” according to the NGO Crop Trust.
The organization said that 65 scientists launched a past project to map out the genomic sequence of pearl millet in a bid to figure out why this climate-tough crop can produce strong yields even in temperatures of 42 degrees Celsius (about 107 degrees Fahrenheit). “Identifying markers for heat tolerance and other climate-resilient traits will enhance breeding efforts for this crop and other dryland cereals that could impact food security for millions of people in arid and semi-arid regions,” Crop Trust said.
The answers to pests and pestilence
The United Nations Food and Agriculture Organization (FAO) says climate change could be delivering more frequent locust swarms, threatening farms over wide swaths of the Sahel and Central Asia. Plant diseases that were once confined to the tropics are increasingly popping up in temperate farming climates, a trend also linked to rising average global temperatures.
Locusts and fall armyworms are among the better known of many insect pests that are spreading with climate change. But farmers can fight back, even without chemicals. The International Maize and Wheat Improvement Center recommends releasing ladybugs into smallholder fields. These colorful beetles prey on aphids and caterpillars. Some species of ants attack the fall armyworm, a particularly devastating crop pest.
Beneficial insects can help farmers fight harmful pests. But what about diseases? The likely solution here is more disease-resistant crop varieties.
The development of wheat varieties that can resist wheat rust helped Norman Borlaug launch the Green Revolution. A great deal of existing agricultural R&D is attempting the same with crops threatened by other crop diseases, and it seems to be working, resulting in disease-resilient rice, maize, and more.
Global warming is a threat to farming everywhere. It’s not just drought and flooding that we need to worry about.
Saltwater intrusion, heat stress, and wider infestations of pests and diseases are some of the other concerns. Smallholder farmers are the most vulnerable to these threats, but innovative R&D can and will help them continue to ensure food security for the world.
— Grow Further
Photo credit: Pearl millet being grown in India as part of a CGIAR research project. C. Bonham/Bioversity International (CC BY-NC-ND 2.0).
