Document: ROZ-3-18-5

Trajectories of agricultural intensification and consequences for non-agricultural ecosystems in Sonora, Mexico.

NAYLOR, R.* ¹, T.BENNING ², P.MATSON ¹, G.ASNER ³ and I.ORTIZ-MONASTERIO ⁴

Stanford University, Stanford, CA ¹
University of California, Berkeley, CA ²
University of Colorado, Boulder, CO ³
Centro International de Mejoramiento de Maiz y Trigo, Obregon, MX ⁴

Abstract:
We are evaluating the causes and consequences of agricultural intensification in the Yaqui Valley, Sonora, Mexico. Using a combination of historical remotely-sensed data and ground-based data and information, we are analyzing the links between agricultural policy and agricultural extent and productivity. Our results illustrate that urban population, land tenure, land management, agricultural yields, and fertilizer use have changed dramatically over the past 50 years. For example, the region's major city did not exist in 1920 and today has over 250,000. Wheat yields have increased from less than 2 in the 1950s to more than 6 T/ha today, and fertilizer use has increased by a factor of 5 over the same time period. These changes are driven by policies external to the Valley itself, including NAFTA and macroeconomic reform policies within Mexico. Using satellite data, we show that land use within the irrigation district has remained relatively constant over the past 50 years, but expansion of land use in the surrounding desert, foothills and coastal zone has dramatically increased. Likewise, the increasing and excessive use of fertilizers within the irrigation district has lead to biogeochemical transfers that affect downstream coastal ecosystems.

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This abstract is being presented at: 1:55 PM in session:
Symposium # 17: Land Use and Land Cover Change: The Last Century and Prospects for the 21st Century.