![]() ![]() Learn- ing from the soil and water management strategies of people who adapted over long periods of time to arid conditions can help current water management in agriculture and support the search for solutions to the growing challenges of limited water resources worldwide. Techniques and strategies used by the O’odham and Hohokam for growing crops indicate advanced knowledge and skill in water conservation and management of soil water and nutrients. Studies of their agriculture could help to affirm and better document this heritage and enhance its recognition. The Akimel O’odham and other Native Americans who have farmed the low desert region of the Southwest have a strong agricultural heritage (Russell, 1908 Castetter & Bell, 1942 Nabhan, 1982, 1984 Rea, 1997 Doolittle, 2000 Hunt & Ingram 2014). Studies to document these older irrigated soils before they are altered provide baseline information useful in assessing change in land resources resulting from agriculture. With the pro- posed additions of irrigation land for the GRIC, some of the older irrigated lands will be brought under intensive modern agriculture in the near future. When completed, the system will consist of 132 km of main water delivery canals and about 3860 km of secondary canals, and convey water to 59,000 ha of tribal and allotted land for future agricultural, com- mercial, and recreational development. ![]() Since 1995, the GRIC has been designing and developing a water delivery system known as the Pima-Maricopa Irrigation Project (P-MIP). ![]() The extensive history of agriculture in the area also makes it possible to address larger questions about long- term soil quality and sustainable agriculture. 450 to 1450, are among the most contin- uously farmed prehistoric fields known in North America. The irrigated fields on the GRIC, spanning about 1000 years from A.D. (McAuliffe & van Devender, 1998 Thompson & Anderson, 2000), so the climatic conditions during the Hohokam occupation of the Middle Gila Valley would have been generally similar to today. The modern desert climate was es- tablished by about 6000 B.C. Those factors combine to make it one of the most challenging desert climates in which Southwestern Native Americans practiced agriculture. With a low elevation of about 350–400 m above sea level, the Phoenix Basin experiences a combination of low precipitation (about 200 mm annual precipitation) and high temperatures (average summer daily maximum temperature above 38 o C Sellers & Hill, 1974). The geomorphic setting is within the Sonoran Desert section of the southern Basin and Range physiographic province, which is generally characterized by elongated mountain ranges alternating with broad alluvial valleys (Morrison, 1991). Unique characteristics and a long agricultural history make the Phoenix Basin, and the GRIC, in particular, an important place to study arid land agriculture. Scientific research to understand agricultural land use and environmental history are important for the future of the Gila River, and studies of Gila River Valley agricultural soils in the Phoenix Basin help to extend the perspective on land use and human–environmental relationships along this important Southwestern stream. The Gila River has undergone many changes historically, including serious environmental degradation and associated desertification processes (e.g., Dobyns, 1981 Rea, 1997). A corresponding diversity of past and present cultures has farmed the Gila River watershed. in the Mogollon Mountains of western New Mexico to its confluence with the Salt River and other key streams in the Phoenix Basin (see Figure 1). ![]()
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