全球受盐影响土壤状况——主要报告（英）_239页_41mb

Summary of the Global Status of Salt-Affected Soils

Core Content

This document presents a comprehensive overview of the global status of salt-affected soils, focusing on their characteristics, causes of salinization and sodification, regional assessments, impacts on food production, and sustainable management strategies. It is a key resource developed by the Food and Agriculture Organization of the United Nations (FAO) through its Global Soil Partnership (GSP) and the International Network of Salt-Affected Soils (INSAS), providing insights into the challenges and opportunities related to these soils.

Main Points

1. Description of Salt-Affected Soils

Salt-affected soils are a distinct group of soils that include naturally saline soils such as mangroves, marshes, coastal wetlands, inland salt flats, and ancient sea beds. These soils support unique ecosystems adapted to high salinity levels and contribute to global biodiversity.

2. Factors of Soil Salinization and Sodification

Several factors contribute to the formation of salt-affected soils:

• Aridity trends: Increased aridity leads to higher evaporation rates and reduced leaching, promoting salt accumulation.
• Freshwater scarcity: Limited availability of freshwater exacerbates the problem, especially in irrigation-dependent regions.
• Sea level rise: Coastal areas are increasingly affected due to seawater intrusion.
• Permafrost thaw: Melting permafrost in some regions leads to the release of salts into the soil.

3. Distribution of Salt-Affected Soils

Salt-affected soils are found globally, with significant areas in arid and semi-arid regions. The document provides a detailed global map (GSASmap) that categorizes salt-affected soils based on their salinity and sodicity levels, highlighting the extent of the issue across different regions.

4. Human-Induced Salinization

Human activities, particularly in agriculture, are a major cause of secondary salinization:

• Deforestation and land use change: Lead to reduced vegetation cover, increasing surface evaporation and salt accumulation.
• Inappropriate irrigation and drainage: Poor irrigation practices and inadequate drainage systems contribute to salt buildup.
• Over-withdrawal of groundwater: Especially in inland and coastal areas, leads to salt intrusion into water sources.
• Canal water seepage: Irrigation canals can cause salt to seep into surrounding soils.
• Overuse of agrochemicals: Certain fertilizers and chemicals increase salinity levels.

5. Regional Assessments

The document includes detailed assessments of salt-affected soils in various regions:

• Asia: Covers methods of salinity and sodicity measurement, irrigation practices, and the most cultivated crops.
• Europe and Eurasia: Includes data on soil management, drainage systems, and crop adaptation.
• Latin America and the Caribbean (LAC): Highlights regional challenges, soil types, and management strategies.
• Near East and North Africa (NENA): Examines the impact of salinization on agriculture and water management.
• North America: Focuses on soil salinity issues, irrigation techniques, and the role of drainage systems.
• The Pacific: Discusses the status of salt-affected soils and their management.
• Sub-Saharan Africa: Reviews the extent of salinization, water scarcity, and the use of brackish water for irrigation.

6. Impact on Food Production

Salt-affected soils significantly reduce agricultural productivity. The document outlines the potential yield loss due to salinity stress, emphasizing the need for improved management practices to sustain food production. It also discusses the effects of salinization on different crops and the importance of sustainable irrigation and drainage systems.

7. Sustainable Management Strategies

The report proposes a range of sustainable practices for managing salt-affected soils:

• Mitigation strategies:
  • Physical measures: Mulching, interlayers, leaching, drainage, surface scraping, compost and plant residue incorporation, biochar, low-rank coal, deep tillage, and land shaping.
  • Chemical measures: Use of gypsum and other calcium-containing amendments.
  • Biological measures: Adjusting planting time, crop rotation, agrobiodiversity, agroforestry, and bioremediation.
• Adaptation strategies:
  • Breeding salt-tolerant crops (including genetic engineering).
  • Domestication of halophytes and other non-conventional crops.
  • Bioinoculants and halopriming to enhance plant resilience.
• Integrated approach: Promotes saline agriculture, combining mitigation and adaptation strategies for effective management.

Key Information

• Global Salinization Challenge: Salt-affected soils are a major threat to agricultural productivity, especially in arid and semi-arid regions.
• Human Impact: Agricultural practices, such as improper irrigation and overuse of groundwater, are key drivers of secondary salinization.
• FAO and INSAS Role: FAO has been actively involved in addressing soil salinization since the 1970s, and the establishment of INSAS in 2019 has significantly advanced global efforts in this area.
• Legal and Policy Frameworks: The report advocates for a robust legal and policy framework to protect natural saline ecosystems and promote sustainable management, referencing agreements like the Ramsar Convention.
• Data and Tools: The GSASmap provides a detailed global assessment of salt-affected soils, including their distribution, intensity, and management needs.

Conclusion and Way Forward

The report concludes that the management of salt-affected soils is critical for ensuring global food security. It calls for a coordinated effort at both national and international levels to develop and implement sustainable practices, protect natural saline ecosystems, and improve policies that support the long-term health of soils. The future of agriculture in saline environments depends on innovation, collaboration, and a balanced approach to soil and water management.