Predicting long-term dynamics of soil salinity and sodicity on a global scale

Abstract

Knowledge of spatiotemporal distribution and likelihood of (re)occurrence of salt-affected soils is crucial to our understanding of land degradation and for planning effective remediation strategies in face of future climatic uncertainties. However, conventional methods used for tracking the variability of soil salinity/sodicity are extensively localized, making predictions on a global scale difficult. Here, we employ machine-learning techniques and a comprehensive set of climatic, topographic, soil, and remote sensing data to develop models capable of making predictions of soil salinity (expressed as electrical conductivity of saturated soil extract) and sodicity (measured as soil exchangeable sodium percentage) at different longitudes, latitudes, soil depths, and time periods. Using these predictive models, we provide a global-scale quantitative and gridded dataset characterizing different spatiotemporal facets of soil salinity and sodicity variability over the past four decades at a ∼1-km resolution. Analysis of this dataset reveals that a soil area of 11.73 Mkm2 located in nonfrigid zones has been salt-affected with a frequency of reoccurrence in at least three-fourths of the years between 1980 and 2018, with 0.16 Mkm2 of this area being croplands. Although the net changes in soil salinity/sodicity and the total area of salt-affected soils have been geographically highly variable, the continents with the highest salt-affected areas are Asia (particularly China, Kazakhstan, and Iran), Africa, and Australia. The proposed method can also be applied for quantifying the spatiotemporal variability of other dynamic soil properties, such as soil nutrients, organic carbon content, and pH.

Irrigation Induced Salinity and Sodicity Hazards on Soil and Groundwater: An Overview of Its Causes, Impacts and Mitigation Strategies

“…Accurately quantifying and identifying irrigation-induced salinity and sodicity hotspots is quite challenging because of the high geographic variability and net changes in the salinity and sodicity levels; nonetheless, certain regions mostly in semi-arid and arid regions are at higher risk because of the inherent saline and sodic nature (chemical composition) of the soil [37]. On a country scale, salinity and sodicity are pervasive in both arid and semi-arid countries throughout the world, including few humid countries such as Bangladesh and Malaysia [38,39].…”

Genetic Mapping Reveals Novel Exotic and Elite QTL Alleles for Salinity Tolerance in Barley

“…(2) Chromosome. (3) Linked DNA marker revealing strongest F-value (4) Centimorgan positions of associated DNA marker. (5) Effect of the DNA marker as QTL main additive effect (M) and QTL × Environment additive effect (M × E).…”

“…(2) Chromosome. (3) Linked DNA marker revealing strongest F-value. (4) Centimorgan positions of associated DNA marker.…”

“…Soil salinization is increasing around the world, especially in arid and semi-arid regions, mainly due to climate change [1,2], and has significant impact on agricultural productivity and sustainability [3]. It has been reported that about one-fifth of the world's total irrigated lands are salt-affected, and Egypt is one of the most significantly impacted countries [4].…”

Micro-Water Harvesting and Soil Amendment Increase Grain Yields of Barley on a Heavy-Textured Alkaline Sodic Soil in a Rainfed Mediterranean Environment

“…Soil sodicity is a constraint of global significance. It has recently been estimated that sodicity, expressed as an exchangeable sodium percentage (ESP) greater than 6%, occurs in surface soils (0-30 cm) in at least 75% of years on approximately 9.2 Mkm 2 of land, with the most severely affected continents being Asia, Africa and Australia [1]. Soil alkalinity is also important in semi-arid landscapes.…”