Climate Change: Agroecological approaches to enhance resilience to climate change
The Green Revolution has performed well in well?endowed areas with a stable climate, adequate water supply and access to inputs and cheap energy. But the necessary fertilizers, pesticides, farm equipment and fuel are derived from dwindling and ever more expensive fossil fuels. At the same time, climatic extremes are becoming more frequent and intensive agricultural systems show a lower resistance and higher vulnerability to such fluctuations. Fortunately, there are alternatives that enhance resilience and ensure high yields.
Little has been done to enhance the adaptability of industrial agriculture to changing and extreme weather events, except for a focus on “magic bullets” such as genetic modification, with crops that are expected to produce under stressful environments.
Almost no work has been conducted on designing management practices that enhance the resilience of monocultures to climate change. But there is ample evidence that agro-ecological designs and practices contribute enormously to this.
In fact, many studies reveal that small-scale farmers who follow agro-ecological practices cope with, and even prepare for, climate change, minimising crop failure. Results from various studies suggest that these practices provide a higher resistance to climate events, reduce vulnerability and make farms more sustainable in the long-term.
many studies reveal that small-scale farmers who follow agro-ecological practices cope with, and even prepare for, climate change
Based on this evidence, various experts have suggested that reviving traditional management systems, combined with the use of agro-ecologically principles, may represent the only viable and robust path to increasing the productivity, sustainability and resilience of agricultural production. In this paper we explore a number of ways in which these strategies can be implemented through the design and management of agro-ecosystems, allowing farmers to adopt a strategy that, in the end, provides more economic benefits.
Diverse farming systems
Detailed analyses of agricultural performance after extreme climatic events have revealed that resilience to climate disasters is closely linked to the level of on-farm biodiversity.
A survey conducted in Central American hillsides after Hurricane Mitch showed that farmers using diversification practices (such as cover crops, intercropping and agroforestry) suffered less damage than their conventional monoculture neighbors.
A survey of more than 1,800 neighbouring “sustainable” and “conventional” farms in Nicaragua, Honduras and Guatemala, found that the “sustainable” plots had between 20 to 40% more topsoil, greater soil moisture and less erosion, and also experienced lower economic losses than their conventional neighbours.
Similarly, those coffee farms in Mexico which exhibit high levels of complexity and plant diversity suffered less damage from Hurricane Stan. And forty days after Hurricane Ike hit Cuba in 2008, researchers found that diversified farms exhibited losses of 50%, compared to 90 or 100% in neighbouring monocultures. Likewise, agro-ecologically managed farms showed a faster recovery in their production than monoculture farms.
These are only a few examples that show how complex agro-ecosystems are able to adapt and resist the effects of climate change. Agroforestry systems have been shown to buffer crops from large fluctuations in temperature, thereby keeping the crops closer to their optimum conditions. More shaded coffee systems have shown to protect crops from low precipitation and reduced soil water availability. This is because the overstory reduces soil evaporation and the roots increase soil water infiltration.
At the same time, intercropping enables farmers to produce various crops simultaneously and minimise risk. Polycultures exhibit greater yield stability and less productivity declines during drought. A study of the effect of drought (Natarajan and Willey, 1986) on polycultures showed that intercropping is enormously successful. Quite interestingly, the rate of overyielding actually increased with water stress, showing that the relative differences in productivity between monocultures and polycultures increase with greater stress.
Another example is that of the intensive silvopastoral systems (ISS), which combine fodder shrubs planted at high densities, trees, palms, and pastures. High stocking levels are achieved through rotational grazing, which allows for the natural production of milk and meat in these systems. At the El Hatico farm, in Cauca, Colombia, a five story ISS composed of a layer of grasses, leucaena shrubs, medium-sized trees and a canopy of large trees has, over the past 18 years, increased its stocking rates to 4.3 dairy cows/ha and its milk production by 130%, as well as completely eliminating the use of chemical fertilizers. 2009 was the driest year in El Hatico’s 40-year record, and the farmers saw a reduction of 25% in pasture biomass, yet the production of fodder remained constant throughout the year, neutralising the negative effects of drought on the whole system.
In response to the extreme weather, the farm had to adjust its stocking rates. In spite of this, the farm’s milk production for 2009 was the highest on record, with a surprising 10% increase compared to the previous four years. Meanwhile, farmers in other parts of the country reported severe animal weight loss and high mortality rates due to starvation and thirst.
The combined benefits of water regulation, a favourable microclimate, biodiversity, and carbon stocks in such diversified farming systems, not only provide environmental goods and services for producers, but also greater resilience to climate change.
Originally published in Farming Matters | June 2012