Dynamic change of salt contents in rhizosphere soil of salt-tolerant plants Effects of Different Vegetation on Rhizosphere Soil Microbial Properties in the Hilly-Gully Region of Loess Plateau Gradient distribution of soil N,P,and K along the distance from Picea mongolica seedlings root surface Characteristics of soil microelements contents in the rhizospheres of different vegetation  in hilly-gully region of Loess Plateau. Soil nitrification in root surface and rhizosphere at late growth stages of rice cultivars with different N use efficiency