秦王川灌区不同绿色覆盖方式预防土壤次生盐渍化效应研究

因灌溉不当和土壤裸露而引发的土壤次生盐渍化问题已成为西部灌区农业可持续发展的主要障碍。通过研究裸地、单作春小麦Triticum aestivum、红豆草Onobrychis viciaefolia和春小麦/毛苕子Vicia villosa 4种处理的土壤可溶性盐分时空动态，分析和对比了它们的动态变化差异。结果表明：在春小麦收获期，3种种植方式对0～20 cm土层均具有明显的抑盐效应,含盐量下降幅度达16.4%～30.5%，其中单作春小麦与单作红豆草和春小麦/毛苕子差异显著，而单作红豆草和春小麦/毛苕子差异不显著；单作小麦使0～80 cm土层积盐14.2%，而春小麦/毛苕子和红豆草使0～80 cm土层脱盐19.7%和23.0%；单作春小麦地土壤含盐量垂直分布表现为中层高（20～60 cm）、上下层（0～20 cm和60 cm以下）低，而单作红豆草和春小麦/毛苕子表现为上层（0～20 cm）低、下层（20 cm以下）高的特征。春小麦收获后，单作春小麦地土壤表层快速积盐，其含盐量甚至高于裸地，而单作红豆草和春小麦/毛苕子地表层盐分变化较小。秦王川灌区若采取春小麦/毛苕子的种植模式，不仅可以预防土壤的次生盐渍化问题，还能多生产36 018 kg/hm2的牧草。

Effect of different green-cover patterns on soil secondary salinification in Qinwangchuan irrigated area

Soil secondary salinification was caused by unreasonable irrigation and bare soil, it has already become a main obstacle of agricultural sustainable development. The spatial and temporal dynamic changes of soil salt content in bare soil, or soil growing Triticum aestivum, Onobrychis viciaefolia, and T.aestivum / Vicia villosa were studied and the difference among four patterns was compared. The results indicated that during the wheat harvest period, three growing patterns had obvious restraining salt effect in 0～20 cm soil layer, and salt content of topsoil was reduced by 16.4%～30.5%.The difference between growing wheat and  O.viciaefolia and T.aestivum / Vicia villosa was significant;  however,  the difference between growing  O.viciaefolia and growing T.aestivum / Vicia villosa was not significant. The soil salt content within 80 cm was increased by 14.2% through sowing spring wheat, but decreased by 19.7% and 23% when sowing T.aestivum / Vicia villosa and O. viciaefolia. The vertical distribution of soil salt content was higher in middle layer (20 60 cm) than in the surface (0 20 cm) and lower layer (60 80 cm) when only growing wheat.  When growing  O. s viciaefolia or T. aestivum / Vicia villosa, soil salt content was lower in the surface than other layers. After spring wheat was harvested, the soil salt accumulated quickly to the surface of the land, and the salt content of topsoil was higher than that in uncovered land. If T. aestivum / Vicia villosa is implemented, it can not only restrain soil secondary salinization, but also produce more forage by 36 018 kg/hm2.