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Global Soil Partnership

Global Map of Salt-affected Soils (GSASmap)

© FAO/Didar Salimbayev

The Global Map of Salt-Affected Soils (GSASmap) is a product containing contributions from over 118 countries with 257, 419 locations containing measured soil data. More than 350 national experts were involved in the harmonization of its input data and methods for mapping salt-affected soils (SAS) and were trained in the state of the art methods for digital soil mapping. Every country then produced their maps following the agreed technical specifications (6). This participatory country-driven process offers more opportunities for future periodic update, which is an important aspect that has been missing in previous global SAS information.

The map represents spatial distribution of SAS information at two depth intervals: 0-30 cm and 30-100 cm including EC, ESP, pH, and classes of salt-affected soils.

The GSASmap represents the spatial distribution of SAS with ECe>2 dS/m, ESP>15% and pH > 8.2 at two depth intervals (0-30 cm and 30-100 cm). With the current information from 118 countries covering 85% of global land area, it shows that more than 424 million hectares of topsoil (0-30 cm) and 833 million hectares of subsoil (30-100 cm) are salt-affected:

  • 85 percent of salt-affected topsoils are saline, 10 percent are sodic and 5 percent are saline-sodic
  • 62 percent of salt-affected subsoils are saline, 24 percent are sodic and 14 percent are saline-sodic.

These estimates based on the submitted data show that more than 3 percent of global topsoils and more than 6% of global subsoils are affected by salinity or sodicity. More than two thirds of global SAS are found in arid and semi-arid climatic zones:

  • 37 percent of SAS are located in arid deserts
  • 27 percent of SAS are distributed in arid steppe (half in cold arid steppe and half in hot arid steppe)

Given that this is a country driven process, there are countries who did not prepare their maps because of lack of data, capacities or because they are not affected by SAS. There are two particular regions, EURASIA and Near East and North Africa (NENA) where SAS is an issue, however, they were not able to prepare their maps because of challenges related to data.

 

GSAS map flyer

Global map of salt-affected soils: GSASmap v1.0
2021

Naturally saline or sodic soils host valuable ecosystems, including a range of rare plants, that are adapted to extreme conditions..

Why do we use the GSASmap?
  1. The GSASmap is an important tool for identifying salt-affected soils where sustainable soil management practices shall be adopted to halt salinization and sodification.
  2. It is a foundation for launching a monitoring framework to track soil salinization and sodification and move into early detection.
  3. As a knowledge product, the map provides useful information for developing evidence-based decisions for conserving natural salt-affected ecosystems, sustainably manage SAS, and restore areas that had lost their original potential due to salt accumulation.

Publications

Status of the World's Soil Resources: Main Report
2018

The 2015 Status of the World’s Soil Resources (SWSR) is a reference document on the status of global soil resources that provides regional assessments of soil change. The information is based on peer-reviewed scientific literature, complemented with expert knowledge and project outputs. It provides a description and a ranking of ten major soil threats that endanger ecosystem functions, goods and services globally and in each region separately.

Voluntary Guidelines for Sustainable Soil Management
2018

The guidelines provide technical recommendations on how SSM can be achieved. The VGSSM are of a voluntary nature and are not legally binding. They elaborate on the principles outlined in the Revised World Soil Charter, considering the evidence provided in the World’s Soil Resources (SWSR) report Status of the World’s Soil Resources (SWSR) 2015 report.

Handbook for saline soil management. Eurasian Soil Partnership implementation plan
2018

This handbook has been prepared for the training workshop on innovative methods of amelioration and use of salt-affected soils, which takes place in Kharkiv, Ukraine, in September 2017..

Mapping of Salt-affected Soils - Technical Specifications and Country Guidelines
2020

This Lesson is the first step of the capacity-building program, which is designed to build national capacities as well as harmonize procedures for developing information of salt-affected soils at the national and global levels..

Technical specifications and country guidelines for Global Soil Organic Carbon Sequestration Potential Map (GSOCseq)
2020

This document provides technical specifications and guidance for the generation of national Soil Organic Carbon Sequestration Potential (GSOCseq) maps at 1km resolution for agricultural lands..

Global map of salt-affected soils: GSASmap v1.0
2021

Naturally saline or sodic soils host valuable ecosystems, including a range of rare plants, that are adapted to extreme conditions..