Soil Salinization Related to Soil Morphological and Physicochemical Characteristics in the Luohui Irrigation Scheme, China

Abstract

The physicochemical properties of soil profiles in the Luohui Irrigation Scheme located along the southeastern edge of the Loess Plateau in China were investigated. The scheme covers part of a river terrace system along the Luohe River. The study area was approximately 31 × 16 km with a north–south gradient and a difference in altitude of about 40 m. The terrace system was divided into a high terrace (HT; 371–389 m), an intermediate terrace (IT; 360–370 m), and a low terrace (LT; 344–359 m). The HT and LT soils showed different trends in salt accumulation in their surface horizons and overall soil profiles. Surface soils and soil profiles on the HT contained a greater amount of clay and silt than those on the LT, which had coarser soil textures. The IT had soils with characteristics intermediate between those of the HT and LT. A negative relationship was found between soil pH and soil electrical conductivity, and positive ones between soil electrical conductivity and silt contents and between water electrical conductivity and the sodium adsorption ratio. Soil morphological characteristics and soil salinization were related to the topographic sequence of the soils. Soil salinization showed spatial pattern within this irrigation scheme and subsoil texture was a useful indicator of the state of salt accumulation. This information may help in developing guidelines for agricultural soil management that are based on the underground water dynamics and soil morphological properties.