Soil microbes in forest land are crucial to soil development and the production of available nutrients for forest trees in extreme arid areas. In this study, we used FAME and PCR-DGGE to study the effects of saline waters for drip irrigation on soil microbes in the shelter-belt along the Tarim Desert Highway in Northwest China. The main results revealed that differences in the soil microbial amounts, fatty acids and DNA segments among the shelter-belt lands drip-irrigated with different salinity waters were significant, and that the soil microbial amounts, diversities of fatty acid and DNA segments decreased with increasing water mineralization. Investigation of vertical differences in the soil microbial amount and fatty acid composition revealed that the maximum appeared at 5-30 cm, while the minimum was observed in the surface layer. The effects of the soil physical properties on the soil microbes were more notable than those of the nutrient contents. The salt composition form was dominated by Na+-Cl--SO42-, and the content of the SO42- was enhanced with increasing water mineralization. In conclusion, a high degree of mineralization of drip-irrigation water may cause the soil to harden and its quality to degrade gradually, which hinders the growth and development of forest soil microbes.
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