Global status of salt-affected soils: Main report

Food & Agriculture Org., 10 dic 2024

Salt-affected soils, characterized by high soluble salts (saline) or exchangeable sodium (sodic), impact plant growth and occur globally, especially in arid and coastal regions. Salinization stems from natural causes (e.g. climate change, sea level rise) and human actions (e.g. poor irrigation practices, excessive water use). FAO’s Global Map of Salt-Affected Soils reveals that over 1 381 million hectares, 10.7 percent of global land, are affected, with Australia, Argentina and Kazakhstan among the most impacted countries. Increasing aridity and water demand amplify soil degradation risks, particularly in developing regions.Climate change and water scarcity threaten agricultural productivity, with substantial crop yield losses observed in saline areas. Halophytes and salt-tolerant crops provide a foundation for saline agriculture, yet many salt-affected soils remain unprotected and inadequately regulated. FAO’s INSAS (International Network of Salt-Affected Soils) underscores the need for updated data, harmonized salinity measurements, and sustainable management practices, with enhanced training and policy frameworks.Mitigation strategies like improved drainage, soil amendments, and the cultivation of salt-tolerant plants are recommended. Key recommendations include scaling sustainable practices, investing in salt-tolerant crop markets, improving data collection and water quality monitoring, conserving ecosystems, and fostering cross-sector collaboration. Such integrated efforts aim to boost food production and resilience in affected regions while protecting vital ecosystems.

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the global perspective	1

Figure 12 Salt reserves on Earth	2

Figure 13 Impact of salts on plant growth	3

Box 11 Halophytes	4

Figure 14 The impact of soil dispersion in sodic soils on soil structure porosity and water percolation	6

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Figure 16 Historic aridity trends	8

Figure 17 Modern aridity trends	9

Table 348 Services most demanded by farmers and extension services to help manage SAS in a sustainable manner in the countries of the Near East ...	96

Table 349 Crops the most cultivated on saline and sodic soils in the Near East and North Africa NENA region	97

Table 3410 Some crops irrigated with brackish water in the countries of the Near East and North Africa NENA region	100

Table 3411 The criteria used to assess the irrigation water quality in Near East and North Africa NENA region countries	101

Table 3412 Type of drainage system implemented in the Near East and North Africa NENA region	105

Table 3414 Type of leaching of saline soils used in the Near East and North Africa NENA region	106

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Table 351 Area of saltaffected saline sodic and saline sodic soils in the United States and Canada	109

Figure 18 Salinization trends under different climate change scenarios	10

Figure 19 Physical water scarcity in 2010 upper figure and projected change in water scarcity by 2050 lower figure	11

Box 12 Salinization of coastal areas of Bangladesh due to increasing sea level rise	13

a topsoil 030 cm and b subsoil 30100 cm	15

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Chapter 2 Humaninduced soil salinization and sodification	20

Figure 22 Dryland unirrigated salinization caused by deforestation	21

The example from India	22

Figure 23 Inland groundwater salinization due to freshwater lens depletion	25

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Figure 25 Fringes of secondary salinized soils due to canal water seepage Kalmykia Russian Federation	29

Table 21 Salt index of fertilizer materials and soil amendments	30

Figure 26 The effect of continued manure amendments on soil salinity in semiarid conditions	31

regional assessments	41

Table 311 Area of saltaffected soils in Asian countries	42

Table 312 Chemical methods used to measure soil salinity in the Asian countries	43

Table 314 Methods of determination of exchangeable Na+ and their distribution in Asian countries	44

Table 316 Method of pH measurement and their application in countries of the Asian region	45

Table 319 Thresholds level for saline and sodic soils	46

Table 3111 The most cultivated crops grown on saline and sodic soils in the countries of the Asian region	47

Table 3113 The criteria used to assess the irrigation water quality in Asian countries	48

Table 3116 Type of leaching of saline soils used in the countries of Asian region	49

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Table 321 Area of saltaffected soils in the Europe and Eurasia region according to available data from the INSAS survey	51

Table 322 Chemical methods used in the Europe and Eurasia region to measure soil salinity according to available data from the INSAS survey	52

Table 323 Method of determining soil sodicity used in the Europe and Eurasia region according to available data from the INSAS survey	53

Table 324 Methods of determination of exchangeable Na+ in the Europe and Eurasia region according to available data from the INSAS survey	54

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Table 327 Map scales used in the saltaffected soils mapping in the Europe and Eurasia region according to available data from the INSAS survey	57

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Table 328 Services most demanded by farmers and extension services to help manage saltaffected soils in a sustainable manner in the Europe and Eu...	61

Table 329 Most cultivated crops grown in saline and sodic soils in the Europe and Eurasia region according to available data from the INSAS survey	62

_headingh7a5m0v7zwftd	63

Table 3211 Crops that are irrigated with brackish water in the Europe and Eurasia region according to available data from the INSAS survey	64

Table 32 12 Types of drainage system used in the Europe and Eurasia region according to available data from the INSAS survey	67

Table 3213 Types of leaching practice in the Europe and Eurasia region according to available data from the INSAS survey	68

Table 331 Area of saltaffected saline sodic and saline sodic soil in some LAC countries and percentage of total country area	72

Table 333 Methods of soil sodicity measurement used in the LAC region	73

Table 335 Method of measurement of cation exchange capacity and their distribution among the countries of the LAC region	74

Table 337 Services most demanded by farmers and extension services to help manage saltaffected soils in a sustainable manner in the countries of th...	76

Table 338 The most cultivated crops on saline and sodic soils in the LAC region	77

Table 339 Some crops irrigated with brackish water in the countries of the LAC region	79

Table 3311 Type of drainage systems implemented in the LAC region	81

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Table 341 Area of saltaffected saline sodic and saline sodic soils in some Near East and North Africa NENA countries in million ha and percentage o...	84

Table 342 Chemical methods used to measure to measure soil salinity in the countries of the Near East and North Africa NENA region	85

Table 344 Methods of determination of exchangeable Na+ and their distribution among the countries of the Near East and North Africa NENA region	86

Table 345 Methods of measurement of CEC and their distribution among the countries of the Near East and North Africa NENA region	87

Table 346 Method of pH measurement and their application in the Near East and North Africa NENA region	88

Table 347 Map scales used in the detailed saline and sodic soil maps in the region at national scale	90

Table 353 Methods of determining soil sodicity used in the North American region	110

Table 355 Method of measurement of cation exchange capacity and their distribution	111

Table 357 Services most demanded by farmers and extension services available to help manage saltaffected soils in a sustainable manner in Canada a...	115

Table 359 Most common irrigation methods used in the North American region	116

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Table 373 Method of soil sodicity used in the Africa region	126

Table 374 Methods of determination of exchangeable Na+ and their distribution over the Africa region	127

Table 375 Method of measurement of cation exchange capacity CEC and distribution over the Africa region	128

Table 377 Map scales used in the detailed saline and sodic soil maps in the Africa region	129

Table 378 Services most demanded by farmers and extension services to help manage saltaffected soils in a sustainable manner in the countries of th...	132

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Table 3712 Agrohydrological models to evaluate water management in saltaffected soils in the Africa region	138

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Table5	148

Table6	150

Chapter 5 Pathway towards the sustainable management of saltaffected soils	151

Box 51 The European Unions policy landscape concerning saltaffected soils	153

Box 52 Tropical mangrove soils	157

Box 53 Soils of the hypersaline inland wetlands in Monegros Northeast Spain	160

Box 54 The agropastoral use of sodic soils in Ukraine	165

Table 51 Laws protecting saline environments with valuable ecosystems summary from responses to INSAS questionnaire	166

Figure 52 Examples of mitigation left and adaptation right strategies	168

Figure 53 Schematic diagram of practices aimed at reduced evaporation interlayers and straw mulching	169

Figure 54 Soil and crop condition under nomulch left and rice straw mulch right in the coastal area of Bangladesh	170

Case studies from Mozambique	171

Figure 55 Schematic diagram of main irrigation and drainage mitigation strategies on saltaffected soil	176

Figure 56 Field trial Emerging AB and established plants C in the lowrank coal application trial to a saline sodic soil in Colombia	180

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Table 52 Common amendments and equivalent quantity for reclamation of sodic soil	183

a under low salinity level and b under high salinity level	184

Figure 510 Sunflower growth condition for early sowing left and late sowing right in the saline area of Bangladesh	185

Table 53 Ameliorating effects of tree plantation on sodic soils and their biomass production India	187

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Chapter 6 Conclusions and way forward	203

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Annex 3 Areas of saltaffected soils of different intensity in the GSASmap at the country level	210

Annex 5 The responses to the INSAS survey Status of saltaffected soils measurement monitoring and management	211

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Parole e frasi comuni

affected by salinity Africa region aquifer area of salt-affected arid assessment Australia Bangladesh biochar biodiversity brackish water Canada carbon cation exchange China climate change coastal crop cropland drainage systems dryland salinity dS/m ecosystems Egypt Environment Environmental Eurasia Europe and Eurasia Global groundwater GSASmap halophytes impact improve increase INSAS Iran Islamic Republic Kenya Kingdom LAC region land leaching Lebanon Libya management of salt-affected mangrove measurement methods Mg2+ models monitoring system mulching NENA NENA region Netherlands Pakistan parameters percent plant practices production questionnaire ratio reported Republic of Iran Research Resources Russian Federation saline agriculture saline soils salinity and sodicity salinity or sodicity salt-affected soils salt-tolerant saturated paste sodic soils sodification sodium Soil pH soil salinity soil sodicity specific strategies Sudan surface surveyed countries sustainable management sustainable soil management Syrian Arab Republic Table Tunisia Ukraine UN-Water United Arab Emirates water management wetlands

Informazioni sull'autore (2024)

Founded in 1945, the Food and Agriculture Organization (FAO) leads international efforts to defeat hunger. Serving both developed and developing countries, FAO provides a neutral forum where all nations meet as equals to negotiate agreements and debate policy. The Organization publishes authoritative publications on agriculture, fisheries, forestry and nutrition.

An intergovernmental organization, the Food and Agriculture Organization of the United Nations (FAO) has 194 Member Nations, two associate members and one member organization, the European Union. Its employees come from various cultural backgrounds and are experts in the multiple fields of activity FAO engages in. FAO’s staff capacity allows it to support improved governance inter alia, generate, develop and adapt existing tools and guidelines and provide targeted governance support as a resource to country and regional level FAO offices. Headquartered in Rome, Italy, FAO is present in over 130 countries.

Informazioni bibliografiche

Titolo	Global status of salt-affected soils: Main report
Autore	FAO
Editore	Food & Agriculture Org., 2024
ISBN	9251393079, 9789251393079

Esporta citazione	BiBTeX EndNote RefMan

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