20 November 2009 | EN
Better crop management, including smarter application of pesticides, can help poor farmers cope with climate change
Innovative agricultural technologies can produce crops that meet climate change challenges, says ICRISAT head William Dar.
Sustainable land and water management combined with innovative agricultural technologies could mitigate climate change and help poor farmers adapt to its impacts.
New knowledge, technology and policy for agriculture have never been more critical, and adaptation and mitigation strategies must urgently be applied to national and regional development programmes.
Without these measures developing countries will suffer increased food insecurity. For the 1.5 billion people engaged in agriculture in the developing world, even a small loss in agricultural productivity could mushroom into a large loss of income.
And new strategies must be built around 'green' agricultural technologies, such as adaptive plant breeding, pest forecasting, rainwater harvesting and fertiliser microdosing, where small amounts of fertiliser are given to each seed.
Water and land use
Water is critical for agriculture across the semi-arid tropics. Although rainfall predictions remain uncertain, scientists agree that climate change will reduce water availability and storage, and warmer temperatures will increase the amount of water needed by crops.
Improving crop production in these regions largely depends on better capture and storage of rainwater. But rainwater harvesting and storage technologies remain underdeveloped. And we know little about the economic viability of such systems — implementing them may well require financial investment beyond the capacity of most rural communities.
As almost 95 per cent of water in developing countries is used to irrigate farmlands, policies to improve irrigation efficiency are also critical. Research is needed on water flows and water quality, and infrastructure needs to be improved.
Better land and crop management are equally important. There are already some promising and economically viable technologies to reduce risk of crop failure, improve soil fertility and increase productivity under variable climatic conditions.
These include methods to reduce agricultural inputs, such as fertiliser microdosing and smarter application of pesticides, as well as technologies for minimising soil disturbance such as reduced tillage, conservation agriculture and crop rotation.
Revising planting dates, plant densities and crop sequences can help cope with delayed rainy seasons, longer dry spells and earlier plant maturity that are already being observed across parts of Africa including Malawi, Mozambique, Zambia and Zimbabwe.
Changes in growing seasons in the tropics can also, to a large degree, be mitigated by redeploying existing improved crop varieties that can cope with a wide range of climatic conditions.
For example my organisation, the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), has developed pearl millet hybrids that can cope with temperatures of 40 degrees Celsius and deliver normal yields with limited water. Our short duration varieties of chickpea and pigeon pea mature in 65–75 days and so can escape terminal drought — lack of water at later stages of growth.
What we need now is a better understanding of the physiological mechanisms underlying heat tolerance so that we can develop more effective screening techniques for desired traits, and identify wider gene pools to develop 'climate-proof' crops.
Developing technologies to help farmers control pests is just as important.
Climate change could have positive, negative or no impact on each pest. But we need better models to assess their global impact as most pest population prediction models have different spatial and temporal scales than global climate models.
Pests are usually controlled by cultural practices, natural enemies, host plant resistance, biopesticides and synthetic pesticides. But many of these control tactics are highly sensitive to the environment and climate change may render them less effective.
It may alter the interactions between pests and their host plants, directly affecting resistance to pest control. For example, there are indications that stem rot (Sclerotium rolfsii) resistance in groundnut is temperature dependent, while in Kenya resistance to sorghum midge (Stenodiplosis sorghicola) breaks down under high humidity and moderate temperatures.
We must urgently identify and develop crops that can resist pests under variable climates. ICRISAT has started work in this area, developing mildew-resistant pearl millet in India, wilt-resistant high-yielding pigeon pea in Malawi, Mozambique and Tanzania, and rosette-resistant groundnuts in Uganda.
Invest in innovation
In the medium term (2010–2050), scientists are well placed to help poor farmers mitigate the challenges of climate change.
The impact of climate change on yields from low-input agriculture is likely to be minimal as other factors will continue to be the overriding constraints on crop growth and yield. Adopting the agricultural technologies outlined above will substantially increase the yields of smallholders, regardless of climate change.
But adopting better 'temperature-adapted' varieties could completely mitigate the climate change effects that result from global warming.
We urgently need better policies that support the adoption of agricultural innovation. Not only will these improve the welfare of rural populations now, but they will also do a great deal to mitigate the future impacts of climate change.
William D. Dar is director general of the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Andhra Pradesh, India.
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