2024年全球盐渍土壤状况报告_240页_41mb

Summary of the Global Status of Salt-Affected Soils

Core Content

This report provides an in-depth analysis of the global status of salt-affected soils, focusing on their characteristics, causes, distribution, management practices, and the impact on food production. It is a collaborative effort by the International Network of Salt-Affected Soils (INSAS) and the Food and Agriculture Organization (FAO), aiming to promote sustainable management and highlight the importance of these soils in both natural and human-induced contexts.

Main Points

1.1 Description of Salt-Affected Soils

Salt-affected soils are those with high salt content, primarily due to natural or human-induced factors. They include saline and sodic soils, which are defined by their electrical conductivity (EC) and exchangeable sodium percentage (ESP) levels. These soils can be found in various environments such as coastal wetlands, inland salt flats, and ancient sea beds. They support unique ecosystems that are adapted to high salinity and have significant biodiversity value.

1.2 Factors of Soil Salinization and Sodification

• Aridity Trends: Increasing aridity is a major driver of soil salinization, especially in semi-arid and arid regions.
• Freshwater Scarcity: Limited freshwater availability exacerbates salinization through reduced leaching.
• Sea Level Rise: Coastal areas are increasingly affected due to seawater intrusion.
• Permafrost Thaw: In some regions, thawing permafrost leads to salt mobilization and soil degradation.

1.3 Distribution of Salt-Affected Soils

Salt-affected soils are widespread globally, with significant areas in Asia, Europe, Latin America, the Near East and North Africa, North America, and the Pacific. The report includes a global map of these soils, distinguishing between topsoil and subsoil.

1.4 FAO's Work on Salt-Affected Soils

The FAO has been actively involved in addressing salt-affected soils since the 1970s, through publications and initiatives like the Global Soil Partnership (GSP). In 2019, the FAO established the International Network of Salt-Affected Soils (INSAS) to promote sustainable use and management of these soils. The first edition of the Global Map of Salt-Affected Soils (GSASmap) was published in 2021, showcasing the power of global collaboration.

2.1 Human-Induced Salinization and Sodification

Human activities significantly contribute to soil salinization and sodification, particularly in agriculture:

• Deforestation and Land Use Change: Leads to reduced water infiltration and increased surface salinization.
• Inappropriate Irrigation and Drainage: Poor irrigation practices and inadequate drainage systems cause salt accumulation.
• Overwithdrawal of Groundwater: Results in inland and coastal groundwater salinization due to overuse and seawater intrusion.
• Canal Water Seepage: Causes secondary salinization in low-lying areas.
• Overuse of Agrochemicals: Can increase salt levels in soil and water systems.

2.2 Non-Agricultural Sources of Salinization

• Road Salts: Contribute to salinization in urban and roadside areas.
• Mining: Releases salts into the environment through tailings and waste.
• Industrial By-Products: Include salt-laden waste and emissions.

3.1 Regional Assessments of Salt-Affected Soils

The report provides detailed assessments of salt-affected soils across different regions, including:

• Asia: Significant areas of salt-affected soils, with various methods for salinity and sodicity measurement.
• Europe and Eurasia: Comprehensive data on soil management and irrigation practices.
• Latin America and the Caribbean (LAC): Focus on sustainable practices and local crop adaptation.
• Near East and North Africa (NENA): Highlight the impact of climate change and irrigation on soil salinity.
• North America: Includes the United States and Canada, with specific irrigation and drainage systems.
• The Pacific: Australia is a key focus, with data on salinity trends and management strategies.
• Sub-Saharan Africa: Details on soil types, management needs, and irrigation practices.

4.1 Impact on Food Production

The report uses the GSASmap to analyze the effects of salinization on food production:

• Land Use Impact: Salt-affected soils are found in various land uses, including cropland, pasture, and forests.
• Crop Yield Loss: Different crops experience varying levels of yield loss due to salinity stress.
• Countries Most Affected: Specific countries are highlighted for their high salinity stress in croplands.

5.1 Sustainable Management Pathways

The report outlines key strategies for sustainable management of salt-affected soils:

• Policy and Legal Frameworks: Emphasizes the need for national and international policies, such as the Ramsar Convention, to protect saline ecosystems.
• Conservation of Natural Saline Ecosystems: Highlights the importance of preserving unique ecosystems that support biodiversity.
• Mitigation and Adaptation Strategies:
  • Mitigation: Includes physical methods like mulching, interlayers, leaching, and drainage; chemical methods like gypsum application; and biological methods like crop rotation and agroforestry.
  • Adaptation: Focuses on salt-tolerant crops, halophytes, bioinoculants, and halopriming.
  • Integrated Saline Agriculture: Combines management practices with agricultural adaptation to improve productivity.

Key Recommendations

• Promote Sustainable Practices: Encourage the use of appropriate irrigation and drainage systems.
• Support Research and Innovation: Invest in saline agriculture and bioremediation techniques.
• Strengthen Legal Protections: Develop policies that safeguard natural saline ecosystems.
• Enhance Monitoring and Management: Implement region-specific strategies for soil measurement and management.

Conclusion

The report underscores the growing threat of salinization and sodification, driven by both natural and human factors. It calls for a unified global approach to manage these soils sustainably, emphasizing the importance of policy, innovation, and ecosystem conservation. The findings and recommendations aim to guide decision-makers, scientists, and environmental advocates in preserving soil health and ensuring food security for future generations.

Key Information

• Total Members in INSAS: 743 from 125 countries.
• GSASmap: First global map of salt-affected soils published in 2021.
• Salinity Thresholds: Defined as EC > 2 dS/m or ESP > 15%.
• Salt-Tolerant Crops: Include rice, wheat, barley, and halophytes like saltbush and mangroves.
• Amendments for Sodic Soils: Gypsum, low-rank coal, and compost are commonly used.
• Legal Frameworks: Inspired by agreements such as the Ramsar Convention.
• Innovative Strategies: Include bioinoculants, halopriming, and saline agriculture.

This comprehensive report serves as a critical resource for understanding and addressing the challenges posed by salt-affected soils on a global scale.