By Joydeep Gupta, IANS,
New Delhi : In an era of climate change leading to more unpredictable rainfall, the way to food security is to diversify what one grows on the field, say international experts.
“Increasing temperatures, declining and more unpredictable rainfall, more frequent extreme weather and higher severity of pest and disease are among the more drastic changes that impact food production,” said Johannes Kotschi of Agrecol, an agricultural research institute in Germany.
“These are the global trends. While we have to worry about this, we also have to remember the global trends mask tremendous regional differences, with the poorest being most at risk both by global climate variations and global commodity price fluctuations,” he said in an e-mail interview.
“Warming in the Indian Ocean and an increasingly ‘el Niño-like’ climate could reduce main-season rainfall across most of Africa, East and South Asia, and Central and South America,” added Janet Cotter and Reyes Tirado, researchers who have been studying the subject and members of the international NGO Greenpeace.
With India at the forefront of countries already bearing the ill effects of climate change, Cotter said in the Greenpeace report: “The biggest problem for food security will be the predicted increase in extreme weather, which will damage crops at particular developmental stages and make the timing of farming more difficult, reducing farmers’ incentives to cultivate.”
“Now genetic diversity of the food crops grown will be most crucial in these highly variable environments and those under rapid human-induced climate change.”
Chinese scientists have shown the importance of this diversity through field trials. Youyong Zhu and colleagues at Yunnan Agricultural University calculated the effect of genetic diversity on the severity of rice blast, the major disease suffered by the rice crop in the field, anywhere in the world.
The researchers found out over 1998 and 1999 that “disease-susceptible rice varieties planted with resistant varieties had an 89 percent greater yield than when they were grown in a monoculture”, Zhu told IANS.
“Mixed varieties of rice produced more grain per hectare than their corresponding monocultures in all cases; close to 20 percent more land is needed in a monoculture to produce the same amount of hybrid and glutinous rice as was produced in a mixture.
“The experiment was so successful that fungicidal sprays were no longer applied by the end of the two-year programme. The practice expanded to more than 40,000 hectares in 2000, and now includes some varieties that were formerly locally extinct.”
Zhu says his team’s findings were “especially remarkable as the yield gains were on top of already high average yields in the region, at nearly 10 tonnes per hectare, among the highest in the world”.
“This shows that greater rice diversity means lower rates of plant disease and greater yields while conserving genetic diversity, all at minimal cost for farmers and the environment.”
Cotter points out that in addition to enhancing food security and climate resilience, diversity in the field also makes the crop more tolerant to drought and flood. Thus, it not only increases productivity, it also prevents soil erosion and desertification, increases soil organic matter and helps stabilise slopes.
“Benefits for farmers include reducing the need for costly pesticides, receiving price premiums for valued traditional varieties and improving their dietary diversity and health,” she added.
The International Assessment of Agricultural Science and Technology for Development (IAASTD), also known as the World Agriculture Report, said this April: “To address expected climate change challenges and impacts, a major role for AKST (agricultural knowledge, science and technology) is needed to increase adaptive capacity and enhance resilience through purposeful biodiversity management.
“Options include irrigation management, water harvesting and conservation technologies, diversification of agriculture systems, the protection of agrobiodiversity and screening germplasm for tolerance to climate change.”
The report, initiated by the World Bank and written by over 400 scientists from around the world, gives these options on how agriculture can cope with climate change:
* Changing varieties/species to fit more appropriately to the changing thermal and/or hydrological conditions;
* Changing timing of irrigation and adjusting nutrient management;
* Applying water-conserving technologies and promoting agrobiodiversity for increased resilience of the agricultural systems;
* Altering timing or location of cropping activities and the diversification of agriculture.