Effects of soil submerging on the formation of saline-sodic soils——Discussion on the causes of saline-sodic soils and the effects of submergence

Saline-sodic soils are widely distributed in the west of Songnen Plain, Northeast China.These soils are regarded as the most difficult types of obstacle soils for improvement and utilization, because of their poor permeability and higher alkalinity.Recently, many studies have shown that the area and degree of salinity of saline-sodic soil have been ever-increasing in an unprecedented scale which raised the public concern.To improve and utilize the soil more effectively, the main cause of saline-sodic soil should be correctly illustrated and understood.In this review, we systematically analyzed and discussed the main factors on the formation of saline-sodic soils, including landscape pattern of surface, physical parameters and chemical properties and summarized the effects of soil submerging on the salt content and soil biota.We found that the west of Songnen Plain was usually remained in a flooding condition because of its special topography and landforms.Also, the impeded drainage caused water moving upward in the soil, which intensified the salt accumulation, and eventually exacerbated the condition of normal soil.Therefore, soil submerging makes an important contribution in exacerbating the saline-sodic soil condition.Meanwhile, we also proposed the priorities and practical ways in three aspects to manage the sodic-saline soil.