Resumen
Central Asia?s Ili River is fed by mountain streams that flow down into an isolated and arid basin that today is shared by Kazakhstan and China. Agriculture in the basin is dependent upon irrigation, which was practiced as long ago as the Iron Age, when early pastoralists constructed ditches to channel water from streams onto nearby fields. Irrigation had become much more common by the 18th century, when the region was controlled by the Dzungarian Khanate. The khanate was toppled by the Qing Chinese in the 1750s in the first of a series of confrontations that destroyed and then rebuilt the basin?s agricultural economy. The region has since been dominated by a succession of Chinese and Russian (and later Soviet and independent Kazakh) governments, each of which recognized the essential role of irrigated agriculture in maintaining control. Thus every cycle of destruction led to reclamation of new lands, resettlement of farmers and upgrading of infrastructure to expand irrigation. This allowed an impressive diversity of fruits, vegetables and field crops to be grown, especially on loess soils of the more fertile upper basin, where tributaries could be easily tapped by gravity flow. Many of these tributaries were entirely diverted by the 19th century, so that they no longer reached the Ili. Large scale irrigation commenced in the 1960s, when the Soviets built Kapchagai dam and reservoir in the lower part of the basin and installed pumps to raise water from the Ili River onto nearby reclaimed sierozem soils, mostly for cultivation of rice. China later constructed a cluster of small- and medium-sized dams that enabled expansion of agriculture in the upper part of the basin. Many irrigated areas along the lower reaches of the Ili in Kazakhstan have been abandoned, but irrigation in the upper basin continues to expand. Declining soil fertility, salinization, pollution, insufficient inflows and adverse economic conditions currently challenge irrigation across the entire basin. Investments are being made in new technologies as a means to sustain irrigated agriculture in the basin, but it remains to be seen if these strategies will be successful.