Cropland Soil Salinization and Associated Hydrology: Trends, Processes and Examples

Abstract

While global food demand and world population are rapidly growing, land potential for cropping is steadily declining due to various soil degradation processes, a major one of them being soil salinization. Currently, approximately 20% of total cropland and 33% of irrigated agricultural land are salinized as a result of poor agricultural practices and it is expected that by 2050, half of the croplands worldwide will become salinized. Thus, there is a real need to better understand soil salinization processes and to develop agricultural practices that will enable production of the needed amount of food to feed humanity, while minimizing soil salinization and other degradation processes. The major sources of solutes in agricultural environments are: (i) the soil itself, and the parent geological material; (ii) shallow and salt rich groundwater; and (iii) salt rich irrigation water. The salinization of soil is a combination of transport of solutes towards the root zone to replenish evaporation and transpiration and limited washing of the soil by rain or irrigation. Therefore, most salinized soils are present in arid and semi-arid environments where precipitation is low and evaporation is high. In this manuscript, examples of soil salinization processes from croplands around the world will be presented and discussed to bring attention to this important topic, to present the latest scientific insights and to highlight the gaps that should be filled, from both scientific and practical perspectives.

The Effect of Flooding on Evaporation and the Groundwater Table for a Salt-Crusted Soil

“…Salinity problems are caused by the presence of saline groundwater at shallow depths as a result of strong evaporation, and this scenario can ultimately lead to land degradation [1,2], especially in arid and semiarid regions [3]. Salt-crusted soils have a high salt concentration [4] and exhibit significant salinization [5]. Salt efflorescence, which is the formation of the salt crust on soils, is a well-known phenomenon in arid and semiarid regions where the annual evapotranspiration significantly exceeds the precipitation [6].…”

“…Salt not only precipitates on the soil surface but also tends to precipitate as subflorescence [18]. Nachshon [5] reviewed the characteristics of salt precipitation in recent studies.…”

Risk Assessment of Soil Salinization Due to Tomato Cultivation in Mediterranean Climate Conditions

“…Salinization is one of the major threats of land degradation [1] that negatively impacts on agricultural sustainability and environmental health, leading to severe losses of soil productivity and desertification processes [2,3]. The accumulation of water-soluble salts in the soil is occurring worldwide, with the most prominent areas being the arid and semi-arid climatic zones [4]. In Europe, salt-affected soils cover an area of about 3.8 million ha, particularly concentrated in the Mediterranean basin [5,6].…”

Policy-Driven Sustainable Saline Drainage Disposal and Forage Production in the Western San Joaquin Valley of California

“…The data are for surveys taken in tall wheatgrass (TWG) and alfalfa (ALF) fields in the spring and fall of 2016 and 2017. 1 The highlighted values are where the R-square was not significant for the multiple linear regression model selected. Table 7.…”

“…Worldwide, it is estimated that 20% of the total farmlands and 33% of the irrigated lands are affected by soil salinity, and that by 2050, half of the farmlands will be salinized [1]. The western San Joaquin Valley (SJV) in the central part of California, USA, is a highly productive agricultural area affected by shallow water tables and soil salinity, as well as high concentrations of selenium and boron in subsurface tile drainage.…”