Salinization is the process by which water-soluble salts build up over the soil profile. Soil salinity is an escalating problem worldwide, especially in arid and semi-arid regions. Plants growing in salt-affected soils may suffer from physiological drought stress, ion toxicity, and mineral deficiency. These problems can lead to reduced growth and biomass. In previous studies on saline-alkali soil amelioration, evaluation of the amelioration measures has focused on the influence of soil salt ions and soil physical and chemical properties. However, this assessment is one-sided and does not consider simultaneously the effects on the growth and physiological conditions of the vegetation. Burying straw in soil as salt-isolation interlayers is a widely used and effective measure for soil salinity control. The effect of burying different amounts of straw on the amelioration of saline-alkali land and vegetation restoration was assessed by conducting field experiments on typical saline-alkaline land in the ecologically fragile area of Ningxia in northwest China. The experiment had four straw burial treatments. These were 2000 kg/hm² (T₁), 7000 kg/hm² (T₂), 12000 kg/hm² (T₃), and 17000 kg/hm² (T₄). The control treatment was no straw burial. All the treatments were arranged in a randomized complete block design with five blocks. Each block was then divided into three plots. The five treatments were randomly assigned to each block. The soil water and salt contents in the 0-100 cm soil layer and spectral reflectance were measured during the Salix babylonico growing season. The results indicated that (1) burying straw as a salt-isolation interlayer could significantly modify underground soil water and salt processes. The T₂, T₃, and T₄ treatments significantly increased the soil water content in the 20-80 cm soil layer compared to CK, and significantly reduced the soil salt content and salt solute concentration in the 0-80 cm soil layer. However, there were no significant differences between these three treatments. The amount of straw buried in T₁ was low. This meant that there was no significant difference between it and the distribution of soil water and salt in CK. Therefore, the salinity control effect was not obvious. (2) The results for the plant leaf spectral reflectance showed that plant growth and physiological condition could be estimated from the results. Straw interlayers significantly improved the physiological condition of Salix babylonico. The spectral reflectance results showed that the T₂ treatment produced the highest chlorophyll content, photosynthetic characteristics, and nutrition levels. Other spectral reflectance parameters also significantly improved compared to CK. The T₃ treatment significantly improved chlorophyll content and photosynthetic characteristics, but was less effective than T₂ and nutrition levels were poor. Carotenoids content and the leaf water content were highest in the T₄ treatment, but other parameters were significantly lower than CK. The T₁ treatment was the worst. (3) Burying straw in the ground as a salt-isolation interlayer could affect the growth and physiological state of the plant by regulating underground soil water and salt transport, and the micro-ecosystem environment. The results for the distribution of soil water and salt, and the spectral reflectance of the plant leaves suggested that the T₂ treatment was the most suitable straw burying amount for the amelioration of saline-alkaline land in the ecologically fragile area of Ningxia.