Acid Sulfate Soils 1

Transcription

1 Acid Sulfate Soils 1

2 Presentation By Narioka, H. Acid Sulfate Soil in rice production for Negara Brunei Darussalam in

3 Acid Sulfate Soil in rice production for Negara Brunei Darussalam 22 Feb Problem Recognition and Problem Soils Hajime NARIOKA, Professor Laboratory of Terrestrial Soil and Water, Division of Environmental Science and Technology, Graduate School of Bioresources, Mie University 1577 Kurimamachiya-cho, Tsu-shi, Mie , Japan Phone/Fax

4 Study 4

5 5 A.S.S. team

6 6 A.S.S. field

7 7 A.S.S. field

8 Setting of groundwater observation system 8

9 Setting of groundwater observation system 9

10 Setting of groundwater observation system 10

11 11 Pond which was affected excessively of A.S.S.

12 Jarosite and crack on the surface at rice field 12

13 Jarosite and crack on the surface of rice field 13

14 14

15 Training items (at field investigation) 1) "Safety First" 2) Existence of ASS by "watch, hear, smell, touch, think" 3) Mechanism of ASS 4) Rice field structure 5) Role and importance of irrigation and drainage 6) Field investigation method 7) Experienced soil layer structure of rice field 8) Thought about "improvement of ASS problem 9) The Team-work and each confidence 15

16 What is the problem (soil)? 16

17 What is the problem (soil)? -Poor Soils Poor soils refer to low potential soil productivity. Potential soil productivity is the maximum productivity shown by soil that is optimum in factors for biological production, including drainage, inclination conditions, and their combination -Problem Soils There are a variety of soils; some soils have serious problems when utilized. These soils are less productive and unsuitable even for the growth of crops because of the presence of extremely specific chemical, physical and biological properties. Typical problem soils are peat soil, saline soils alkaline soils and acid sulfate soils. Globally, Vertisol, Planosol, heavy clay alluvial soil, as well as strong weathering soil in the tropical zone are also considered to be problem soils. 17

18 Important information for research: Topology and Soil Profiles 18

19 Topology Important information -Natural resources -Land use -Topology -Field (in situ) -Environment 19

20 Soils Important items -Poor Soils -Problem Soils Exercise -Saline Soil -Acid Sulfate Soil -Peat Soil - Vertisols 20

21 Soil Profiles Ⅰ Ⅱ Ⅲ Ⅳ Peat Soil Saline Soil Saline Soil Acid Sulfate Soil in the wood area in the hazard area 21

22 Case of Problem Soils - Acid Sulfate Soils - Saline Soils - Vertisols 22

23 Acid Sulfate Soils Case of Problem Soils Acid sulfate soils are covered 43.6% of Africa, 38.2% of Southeast Asia and 16.6% of South Asia. The area of acid sulfate soils reaches about 12 million hectares worldwide, most of which is located in tropical mangroves in Africa and Southeast Asia. The acid sulfate soils zone in Southeast Asia is considered to be potential farmland, but is not farmed because of its strong acidity. Acid sulfate soils oxidizes when sulfate oxides in the soil are supplied oxygen due to land draining, leading to the formation of sulfuric acid and subsequent strong acidification of the 23 soil to ph 3 or lower.

24 Saline Soils Case of Problem Soils Saline soils are distributed in the semi-arid, arid, coastal and poor-draining zones in the world. Definition by the U.S. Department of Agriculture (USDA): -Electric Conductivity (ECsat; saturated extract) 4 ms/cm -Exchangeable Sodium Percentage (ESP) < 15% -ph <

25 Vertisols Case of Problem Soils Black Cotton Soil (Africa and India), Regur (India), Gray and Brown Soils of Heavy Texture (Australia) etc. This requires material with a high shrink-swell potential plus alternate wetting and drying. Vertisols are very slowly permeable, once the cracks swell shut, and slow infiltration is a problem in irrigation. They have a low plant-available water-holding capacity, but a relatively high total water-holding capacity. Because of their low permeability, once they have wet-up, Vertisols are good for paddy (wet) rice culture, because entrapped (diked) water does not 25 leak away.

26 Strategies 26

27 Strategy (1) (Important information and items are understood and developed into the strategy) -Investigation/Research -Administration (government policy) -Civilian Activity (civilian productivity) -Living Persons (human life) 27

28 Strategy (2) 1.Time scale and spatial scale 2.Topological information (landform, coastline and water boundary) 3.Policy in the country (viewpoint to the problem) 4.Meaning of "Development, Protection and Conservation" 28

29 Strategy (3) (The necessary information) -Map (soil, soil profiles, land use, vegetation, topological, etc.) -Remote sensing, GIS etc. -Soil researcher -Professional of the Soil Investigation -Soil Science -Soil Conservation -Consideration of "Development, Protection and Conservation" 29

30 Plan Formulation for Improvement/Conservation 30

31 Procedure for approaching 1.Policy (viewpoint to the problem) 2.Time scale and spatial scale 3.Land resources (landform, coastline and water boundary)

32 Necessary information (1) -Map (soil, soil profiles, land use, vegetation, topological, etc.) -Remote sensing, GIS etc. 32

33 Necessary information (2) -Soil researcher -Soil investigater -Soil scientist -Engineer -Designer 33

34 Research for land use 1. Check point (1)Soil properties (2) Water condition (3) Land classification in consideration of topography and social

35 Research for land use 2. Strategies a) Drainage and dry field farming by control of groundwater b) Rice field production by irrigation and flood control c) Mixed cultivation by control of groundwater level d) Land condition which pyrite is oxidized or not e) Local community in regional participation f) others

36 Research for land use 3. OK? or NG? Development, Conservation, Protection Estimation is not easy for "Peat Soil and Acid Sulfate Soil Mechanism in the field of Acid Sulfate Soil is unexplained

37 Acid Sulfate Soils Process and Strategy 37

38 Reports 1)Department of Agriculture(2008): Soils and Land Suitability of the Agricultural Development Areas, Soil Fertility Evaluation/Advisory Service in Negara Brunei Darussalam Volume 1, Contract: LTN/6/31/2003(10) 2)Department of Agriculture(2008): Soil Management in the Agricultural Development Areas, Soil Fertility Evaluation/Advisory Service in Negara Brunei Darussalam Volume 2, Contract: LTN/6/31/2003(10) 38

39 Soil Profiles Ⅰ Ⅱ Ⅲ Ⅳ Peat Soil Saline Soil Saline Soil Acid Sulfate Soil in the wood area in the hazard area 39

40 What is ASS? 40

41 Acid Sulfate Soil Characteristics (1) Strong acidity (ph3) (2) Oxidation of deposition below water surface or mud (local lake or sea) (3) These are called Acid Sulfate Soil (ASS) by origin material (4) There is easy to be ASS in the Geologic period 41

42 Mangrove area ASS in the world is distributed around 12,000,000ha. Most of ASS area is in Mangrove area. ASS area in Southeast Asia is Potential farmland. 42

43 Mechanism of A.S.S. 43

44 Why is A.S.S. Generation of Acid Soil has two process. (1)Accumulation process of sulfide (2) Sulfuric acid process by oxidation. Physical, Chemical and Biological process 44

45 Accumulation process of sulfide(1) Process: Marine and Volcanic Original materials: Pyrite(FeS 2 ) 45

46 Sulfuric acid process by oxidation(2) Oxidation of Sulfide ph3 Generation of Sulfuric Acid Pyrite(FeS 2 ) Chemical and Biological Oxidation 46

47 FeS 2 Pyrite 化学的酸化 Fe 3+ SO 2-4 H + FeS 2 +2Fe 3+ 3Fe 2+ +2SO 0 S 0 Fe 2+ 化学的酸化 Fe 3+ 酸化初期では重要な酸化剤 酸化初期では重要な酸化剤 SO 2-4 H + Fe 2+ 化学的酸化 O FeS 2 +7/2O 2 +H 2 Fe 2+ +2SO H + 2 Fe 2+ Fe 3+ 2S 0 +12Fe 3+ +8H 2 O 12Fe 2+ +2SO H + 微生物的酸化 (T. ferrooxidans) O 2 Thiobacillus thiooxidans & Thiobacillus ferrooxidans 微生物的酸化 (T. thiooxidans and T. ferrooxidans ) O 2S 0 +3O 2 +2H 2 O 2SO H + Thiobacillus ferrooxidans Fe 2+ 1/4O 2 +H + Fe 3+ +1/2H 2 O Fe 3+ 3H 2 O Fe(OH) 3 +3H + ph4 加水分解 有機配位子の酸化 Fe(OH) 3 Ferrihydrite 3Fe(OH) 2+ +2SO 2-4 K + KFe(SO 4 ) 2 (OH) 6 KFe 3 (SO4) 2 (OH) 6 Jarosite? α-feooh Goethite ph 4 加水分解加水分解? FeSO 4 7H 2 O Melanterite 風化脱水蒸発 FeSO 4 4H 2 O Rozenite FeSO 4 H 2 O Szomolnokite パイライト酸化の終了 土壌酸性化の停滞後, 土壌の中和過程へ移行 溶解 酸化 酸化 加水分解 Pyrite(FeS2) Fe 2+ Fe 3+ 4(SO4) 6(OH) H 2 O 溶解脱水 再配列 Copiapite 脱水 再配列 α-fe 2 O 3 Hematite Most suitable temperature Thiobacteria : SO 2-4 H + 図 1 パイライトの酸化と関連鉱物の生成過程概要 ( 参考 :Nordstrom,1982 および日本化学学会,1999) Process of Oxidation 47

48 Field of A.S.S. 48

49 Southeast Asia: Peat soil and A.S.S. 1. Peat soil, flooding and shallow groundwater level 2. Natural environments (groundwatert, soil and wildlife etc.) 3. Local economy and social 4. Farmland development (suitable land use, drainage control, suitable cultivation, suitable management etc.) 49

50 Problems excavation of A.S.S. 1. Physical and chemical viewpoint of the soil (1) Affected by the flood with high groundwater level (2) Rapid subsidence of surface soil (3) Toxic organic matter for crops production (4) Surface soil is acidified when pyrite layer is oxidized (5) Lack of inorganic fertility (artificial manure), and disproportion of effect of fertilizer (6) Groundwater situation and soil environment is changed (7) others 50

51 Problems excavation of A.S.S. 2. Environmental conservation and management (a) Control of peat soil subsidence and groundwater flow (b) Water control/management: drainage and irrigation (c) Suitable cultivation system (d) Control of microbe and harmful insect (e) Evaluation of environmental influence, and geographical investigation (f) Evaluation of social demand (g) Suitable land classification (h) others 51

52 Soil layer structure (in Japan) of a typical rice field Ridge/Levee Irrigate-water Plow-soil Hard-pan deeper 15~20cm 10cm Soil Hardness(Yamanaka) 24mm Subsoil 52

53 Seasonal changes of soil surface conditions in Japan a) well-drained in region with low rainfall b) poorly drained in region with high rainfall 53

54 Percolation in saturated and unsaturated subsoils in Japan 54

55 Thank you. ありがとうございました 55