文摘
The degradation of irrigated lands through the process of soil salinization, the buildup of salts in the soil, has hampered increases in agricultural productivity and threatens the sustainability of large-scale cultivation in critical agricultural regions of the world. It is estimated that a significant portion of the agricultural land in the lower Colorado River basin is afflicted with varying degrees of soil salinization and insufficient attention has been given to the human-environment relationship driving this form of land degradation. Recognized as a critical agricultural region, the Mexicali Valley of Baja California, Mexico cultivates a significant portion of North America's fresh winter produce, with a particular focus on green onions. The spatial distribution of soil salinity is mapped using remotely sensed imagery and its proximate causes and distal drivers are explored using a mixed methods approach, linking macro-scale institutional and economic influences to micro-scale farmer decision-making and environmental conditions. Surface soil salinity is found at levels sufficient to threaten productivity, with a clustered pattern of occurrence that supports the contention for human-induced soil salinity linked to irrigated agriculture. Land-tenure practices, scarce economic investments in agriculture, institutional failure to address soil salinization, and a growing global demand for produce account for the degradation witnessed. This research contributes to the global sustainability effort by clarifying the human-environment relationship resulting in salinity driven land degradation afflicting irrigated agriculture and endangering our global environment.