The Yaqui Valley site of CIMMYT’s primary wheat experiment station, is one of just a few regions around the world being observed by two new NASA satellites. The Valley’s unique location, bounded on one side by the ocean and by a mountain range on the other, gives researchers the opportunity to investigate the long-term effects of intensive farming on natural marine and terrestrial ecosystems, which have implications for global warming and, ultimately climate change.

A Long-Distance View to Prevent
Local Ecological Failures

“The Valley is a wonderful lab for studying what happens to neighboring ecosystems when farming is intensified,” says David Lobell of the University of Colorado’s Department of Geological Science and Environmental Studies.

Remote sensing, which started in the Yaqui Valley in 1999 with Landsat 7, is a new way of watching the highly productive area, which has been the object of global attention for decades. It is the birthplace of modern semidwarf wheats. Forty percent of the wheat produced in the developing world comes from irrigated environments like the Yaqui Valley so results of these investigations are likely to be relevant far beyond Mexico—for example, in the most important wheat-growing areas of South Asia. This is significant, given that in the next 25 years, 90% or more of the additional wheat grain needed to feed the rising population in developing countries will have to come from intensive farming systems. As agriculture intensifies, measures need to be taken to minimize environmental damage and curtail the emission of greenhouse gases.

In 2000, scientists working with the Landsat data enlisted the help of CIMMYT researchers, who were in an ideal position to provide on-the-ground data to construct models for interpreting the Landsat data. So far the satellites’ perceptions have generally jibed well with CIMMYT’s field information.

The satellite technology is already helping farmers in the Yaqui Valley. For three years, satellite images predicted with a very small margin of error (5%or less) how much wheat grain would be produced in the Yaqui Valley. Made early in the crop season, these predictions can help farmers to avoid over-marketing their crop.

New Ways to Preserve Ecosystems, Biodiversity

A satellite image of northwestern Mexico reveals algae forming off of the coast, perhaps as a result of fertilizer runoff.

The new satellites are so sensitive they can pick up detailed information on individual farmer’s fields. They can do more than tell which crops farmers are growing today—they can tell which ones they grew several months ago. Based on the images, CIMMYT scientists may soon be able to tell producers, for example, why their fields do not yield as much as others, enabling them to find the right solution to their problems.

“Everything we learn from this project* will help develop cropping practices that are highly productive but minimize the impact of farming on adjacent ecosystems,” comments Ivan Ortiz-Monasterio, CIMMYT agronomist collaborating on this study. “Satellite images, combined with models, could help estimate how much of the nitrogen applied to fields goes into the groundwater, the atmosphere, or the ocean via the drainage system. For example, nitrogen that ends up in the ocean generates patches of algae that can be seen from high above. Those images would confirm the need for more efficient fertilizer practices.”

In a terrestrial ecosystem, the escape of large quantities of nitrogen into the atmosphere is apparent when areas of lush vegetation develop downwind from fields where nitrogen fertilizer has been applied. Excess nitrogen takes the form of nitric oxide and ammonia and mixes with clouds. When it rains, the areas below are fertilized by the precipitating nitrogen and become perceptibly greener. Far from benefiting the ecosystem, fertilization upsets the balance of plant species: some species respond well to it, crowding out others that may disappear altogether. This imbalance has serious implications for plant biodiversity.

High-Tech Help for Poor Farmers

An efficient means of avoiding excessive fertilizer applications is precision agriculture, which requires accurate maps of crop yields to help farmers understand soil variation and how much their fields can yield. By significantly increasing production efficiency, precision
agriculture could improve farmers’ incomes and reduce the harmful effects of farming on the environment. The cost of producing crop yield maps is too high for developing world farmers, but a low-cost alternative is to make accurate estimates of crop yields based on satellite images (see figure).

The amount of organic matter in the soil affects crop production and also has implications for carbon sequestration. When excessive amounts of carbon dioxide are released into the atmosphere, they contribute to global warming. In carbon sequestration, the amount of carbon dioxide in the atmosphere diminishes because it is taken out of the air and stored, for example, in soil organic matter. Images taken during the summer cycle, when not much is planted in the Yaqui Valley may reveal how much organic matter is left in the soil after decades of intensive farming. Soil organic matter can be built up through conservation practices, and satellite data could show which practices work best in the region.

Farming for—Not against—the Environment

Satellite images can also tell how much carbon dioxide is taken up by crops in the Yaqui Valley. Says Gregory Asner, also of the University of Colorado, “Experts believe that information on carbon dynamics in the region could provide the basis for establishing policies to regulate the emission of greenhouse gases in the Yaqui Valley and become the model for regulations in other regions.”

If practices to improve the environmental effects of farming can be developed in the Yaqui Valley it is very likely they will work in similar agricultural environments in the developing world. The application of techniques like satellite imaging combined with ground data to study a farming community and its environs is possible in the Yaqui Valley partly because of the trust that has developed over many years between CIMMYT researchers and wheat producers. If similar collaborative research could be initiated in other important wheat-producing areas of the developing world, the prospects for better production would improve, and global warming would be reduced.

* A CIMMYT/Stanford University/University of Colorado collaborative study.

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For more information: Ivan Otriz-Monasterio (i.ortiz-monasterio@cgiar.org)

 
Published on October 2001

August, 2004

Annual Report 00-2001