Urbanization has decimated farmland in developed countries like the United States, but that's not the case everywhere. As populations in some developing countries swell, farmers are cultivating more and more land in a desperate bid to keep pace with the ever-intensifying needs of humans.

As a result, agricultural activity now dominates more than a third of the Earth's landscape and has emerged as one of the central forces of global environmental change, according to scientists at the Center for Sustainability and the Global Environment (SAGE) at the University of Wisconsin-Madison. Some of that land-use creep has negative environmental consequences such as deforestation, water pollution, and soil erosion.

To better understand ag's global footprint, SAGE researchers are tracking the changing patterns of agricultural land use around the world, including a look at related factors such as global crop yields and fertilizer use. They've distilled that information into computer-generated maps, which are being presented this week at the fall meeting of the American Geophysical Union.

The exercise is beginning to cast light on some emerging trends. Countries such as Argentina and Brazil, for instance, have increasingly cleared forests to grow soybean, a legume that has never been a traditional crop of Latin America. Scientists say the surge in soybean production there has a lot to do with the booming demand for soy at the other end of the world -- in China. Meanwhile, longtime soybean farmers in the U.S. -- the world's top soybean producer -- are growing increasingly insecure about their place in the global market.

But scientists risk missing important regional and local trends by taking only a global approach to land use change. To help bridge that gap, SAGE researchers say they are working towards a new "Earth Collaboratory," an Internet-based data bank that would simultaneously draw on the knowledge of global scientists, local environmentalists and everyday citizens.