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Land degradation resulting from soil salinity is a primary problem in arid farmland. This study clarifies the characteristics and regulation of reclaimed salinized farmlnd in a desert oasis. As a case study, we examined an alluvial fan oasis in the Manas River Valley using fixed position experiments, spacial substitutes, and a trend estimation model derived from principal component analysis. In this way, we analyzed the succession of plant and soil characteristics on farmland at the bottom of alluvial fan oasis. With increasing time following reclamation, perennial haloduric plants were replaced by annual plants. The area then entered a stable stage from 6 to 8 yr following reclamation. The total salt decreased gradually and then increased, while soil nutrients showed the opposite trend. The trend estimation model derived from principal components analysis revealed that the general soil quality improved over the first 10 yr before declining thereafter. By systematically analyzing the various indices of soil quantity, an early warning of changes in soil quality can be provided 10 to 15 yr in advance.
