Agriculture is important for food security. Fertile soil is really needed in agriculture, however, all soil in the world is not fertile. In most areas in the world, when we grow crops we can also find some problem soil. There are many technologies on how to manage problem soil. In this ppt, you can clearly know what is problem soil and how to manage this soil.

1. Problem soils and their
management
Thu Zar Win (Ph.D)
Staff officer
Department of Agriculture (Land use division)
Myanmar 1

2. The problem soil
▪ Soil that has agricultural problems due to the soil’s unsuitable
physical and chemical properties, or less suitable for cultivation.
▪ Productivity – lower (due to inherent unfavorable soil condition)
2

3. Types of
problem soils
2. Chemical Problem soils
3. Biological Problem soils
1. Physical Problem soils
3

4. ❖ Permeability - movement of air and water through the soil
- the property of the soil to transmit water and air
❖ It is important because it affects the supply of root-zone air, moisture & nutrients
available for plant uptake
Why is permeability
important for soil?
1.1. High permeable soils & Slow permeable soils
1. Physical Problem soils
4

5. Good arable soil,
✓ possible for plant roots to obtain both air and water
Sand
➢ drains too fast (high permeable)
Clay
➢ doesn’t infiltrate & drain fast enough (slow
permeable)
5

6. မ ြေဆီသြဇာ
မ ာင််းြေွန်မြာမ ြေ
❖ အပင်အတွ ်ြေရှိြေ ြစ်လှိိုအပ်မြာ အြေ ာ်းလှိို၊ အနည််းလှိို အဟာရဓာတ်ြေ ာ်းမပေါြေ ာ်း
❖ မ ြေမဆွ်းဓာတ်လိုုံမလာ ်စွာပေါဝင်
❖ မ ြေခ ဉ်ငုံ ှိန််းြင့််တင့််ြေှတ
❖ မ ြေ ပြု ပင် ခင််းလိုပ်ငန််းြေ ာ်းလိုပ်မဆာင်ရန်လွယ် ူ
❖ မရထှိန််းစွြေ််းအာ်းမ ာင််းြေွန်
❖ မ ြေဆီလာတှိို ်စာ်းခုံရြေု နည််းပေါ်း
❖ အ ှိြု်း ပြု အဏိုဇီဝ ြ ်ရှိြေ ာ်း က ယ်ဝ မပေါြေ ာ်း
6

7. High permeable soil (Sandy Soil)
➢ Generally clay < 10 %, Sand > 65 % soils
➢ Sand particles - large, irregularly shaped bits of rock
➢ Large air spaces between the sand particles allow water to drain very quickly
➢ Nutrients tend to drain away with the water, often before plants have a chance to
absorb them
➢ Thus, sandy soils are usually nutrient-poor
7

8. High permeable soil (Sandy Soil)
➢ Sandy soil has so much air in it that microbes consume organic matter very quickly
➢ Sandy soils contain very little clay or organic matter, they don't have much of a crumb
structure
➢ The soil particles don't stick together, even when they're wet
8

9. Sandy soil constraints
➢ Poor soil structure
➢ Low water holding capacity & high infiltration rate
➢ Subsoil constraints / hard pans
➢ Poor establishment (poor root anchorage to the crops
grown)
➢ Poor fertility/ low N supply / low organic matter
➢ Low biological activity - root disease/herbicide residues
➢ Wilting symptoms in plants appear frequently
9

10. Management of high permeable soil
➢ Add well-rotted manure or finished compost
➢ Mulch the plants with leaves, wood chips, bark, straw mulch
➢ Add at least 2 inches of organic matter each year
➢ Grow cover crops or green manures
10

11. Management of high permeable soil
➢ Application of clay soil up to a level 100 t ha-1 based on the severity of the problem
and availability of clay materials
➢ Providing polythene sheets below the soil surface to reduce infiltration rate
➢ Frequent irrigation of water
➢ Frequent split application of fertilizers and use slow release fertilizers
11

12. Low permeable soil (Clay soil)
➢ Clay - heavy soils & slow permeable soils
➢ Generally, Clay contents > 30 % in 20” of top soils
➢ Clay particles are small, flat & pack together so tightly that there is hardly any pore
space at all
➢ When clay soils are wet, they are sticky and practically unworkable
12

13. Clay Soil
➢ When dry they become hard and cloddy, and the surface cracks into flat plates
➢ Low in both organic matter & microbial activity
➢ Plant roots are stunted because it is too hard to push through the soil
13

14. Clay soil constraints
➢ Infiltration rate - low
➢ Increases the - runoff (which removes more nutrients )
➢ Poor aeration
➢ Erosion of surface soils
➢ Impeded drainage leads to water logging
14

15. Management of slow permeable soil
▪ Application of organic matter
▪ Formation of ridges and furrows
▪ Providing open/ subsurface drainage
▪ Huge quantity of sand /red soil application to change the
texture
▪ Contour /compartmental bunding to increase infiltration
▪ Deep ploughing during summer to enhance infiltration
15

16. 1.2. Hard pan
▪ Hardpans, hard layers, or compacted horizons, either surface or subsurface, are
widespread problems that limit crop production.
▪ a dense layer of soil, usually found below the uppermost topsoil layer.
16
Formation:
1) Due to continuous tillage to a constant depth(5–10 cm).
2) Due to deposition of CaCO3, iron and silicate materials in subsoil

17. lime-cemented hardpan found in arid area. It is
white or light in color, soil over it is usually alkaline.
layer of clay soil. The clay may be hard when
dry and softer when wet, but always impedes
flow of water, causing drainage problems.
layer of dense, compact cemented silt & fine
sand. It is hard when dry, but brittle & fragile
when wet.
formed by action of moldboard plows.
compacted by foot traffic.
Caliche
Claypan
Fragipan
Plowpan
Traffic pan
17

18. Technology to overcome the sub soil hard pan
▪ The field is to be ploughed with chisel plough (loosen and aerate soil)
▪ Farm yard manure at 12.5 t ha-1 is to be spread evenly on surface.
▪ Addition of organic compost & manure to soil - The bacteria can help reduce hardpan.
▪ Adding organic matter - the key to loosening hard soils
18
Impacts
▪ High bulk density (>1.8) (penetration resistances that limit root growth,
reduce water & airflow)
▪ Lowers water holding capacity, available water, movement of air & nutrients
▪ Limited root growth leads to limited crop water & nutrient uptake.
▪ Reduced water flow prevents rainfall or irrigation water from filtering into
the soil profile chisel plough

19. 1.3 fluffy paddy soil
major characteristics
Low bulk density of the topsoil resulting in the
sinking of farm animal, labourers & poor anchorage
to paddy seedlings
19

20. Causes
➢ due to the continuous rice-rice cropping sequence
➢ The traditional method of preparing soil for transplanting rice consists of puddling
which results in substantial break down of soil aggregates into a uniform structureless
mass
➢ Solid and liquid phases of the soil - changed
➢ Under continuous submergence of soil for rice cultivation in a cropping sequence of
rice-rice-rice, soil particles are always in a state of flux and the soil strength is lost
leading to fluffiness of the soils
20

21. Constraints of fluffy paddy soil
➢ This type of soil has high clay content.
➢ Animals or tractors may sink in the soil while working
➢ During puddling operations, an invisible drain of finance for the farmers due to high
pulling power needed for the bullocks and slow movement of labourers
➢ The transplanting operation becomes difficult in these soils
21

22. Management of fluffy paddy soil
➢ 8-10 times passing of 400 kg stone roller or oil drum with sand inside
➢ Sand can be applied if necessary
➢ When the soil is in semi dry condition along with addition of lime 2t ha-1 once in
three years
➢ Growing of garden land or irrigated upland crops after rice – rice cropping system
22

23. 23

24. ➢ Deeper soils can provide more water and nutrients to plants than shallow soils
▪ Deep > 36”
▪ Moderately – 20-36”
▪ Shallow < 20”
▪ Very shallow < 10”
Trees and shrubs that grow in shallow soils have less physical support from their
root systems
1.4. Shallow Soil
24

25. ❖ Soil depth - a pivotal role to the crop performance of both annual & perennial crops
❖ Perennial crops - more affected by soil depth (longer growth)
❖ Higher soil depths - expand plants anchorage & supply capacity to sustain the
performance for much longer time period
25
How does soil depth impact
plant growth and
development?

26. Formation of shallow soil
➢ formed due to the presence of parent rocks immediately below the soil
surface
➢ Topography - strong influence on soil development
➢ Soils on the side of hills tend to be shallow, due to erosional losses
26

27. Constraints
➢ Low effective soil volume, poor nutrient status & water holding capacity
➢ Poor growth & development of crops
➢ Fertility of soil is exhausted within 2-3 seasons thus reducing the yield of crops
in subsequent seasons
➢ Restricts root elongation and spreading
➢ Difficult to drainage
27

28. Management
➢ Drip irrigation with fertigation
➢ Polythene/grass mulches
➢ Selecting a short duration crop species
➢ Deep plough & harrowing
28

29. Management
➢ Higher and frequent application of organic & inorganic sources of nutrients
➢ Judicious irrigation management
➢ Growing shallow rooted crops
➢ Frequent renewal of soil fertility
➢ Growing crops that can withstand shallowness (Mango, fig, tamarind, and
cashew etc) သရက်သီီး၊သဖန်ီးသီီး၊မန်ကျည်ီး၊သီဟိုဠ်
29

30. 2.1. Salt affected soils
2. Chemical Problem soils
30
❑ The primary processes involves in salt accumulation in soil are;
▪ Weathering of rocks and parent materials
▪ Climate (Arid & semiarid regions where evapotranspiration greatly exceeds
precipitation)
▪ Coastal Area (flooding near ocean)
▪ Poor irrigation water (high salt)
▪ Drainage restriction

31. ❑The most common soluble salts in soils are –
Cations (Ca+2, Mg+2, and Na+)
Anions (Cl-, SO4
-2, and HCO3
-)
Moreover,
K+, NH4
+, NO3
-, CO3
-2 are also found in most soils, but in smaller quantities
▪ The salt-affected soils can be primarily classified as saline soil and sodic
soil.
Saline soils - excessive amounts of soluble salt
Sodic soils - high amounts of exchangeable sodium
31
Salt affected soils

32. 2.1.1 Saline soils ဆ ားပ ေါက်ပ ြေ (white alkali soils )
Formation
▪ occur mostly in arid or semi arid regions, in
water logged and swampy area
▪ there is less rainfall available to leach and
transport the salts
▪ high evaporation rates - concentrate salts in
soils and in surface waters
Impact
▪ interfere - germination & growth of most plants
▪ water uptake & nutrients uptake by plants restricted
▪ microbial activity is reduced.
▪ Specific ion effects on plants - due to toxicity of ions like chloride, sulphate, etc.
▪ Effect vegetation and water quality
32

33. Saline soils ဆ ားပ ေါက်ပ ြေ (white alkali soils )
(a) အရရောင် – အဖဖြူရရောင် (Usually white)
(b) ရိုပ်ပိုင်ီးဆိုင်ရော လကဖဏောမျောီး (Physical Characteristics )
(i) တည်ရဆောက်ပို (Soil Structure )– ရကောင်ီး (Usually good)
(ii)ရရစမ်နိုင်စွမ်ီး (Infiltration rate) – ဖမင် (High)
(iii) ရဖမကကီီး၏ ရလဝင်ရလထွက် (Soil Aeration) – ရကောင်ီး (Good)
33

34. (c) ရူပ၊ဓောတို လကခဏောမျောီး (Physicochemical Characteristics)
(i) EC of the saturation soil extract is more than 4 dSm-1 (>4)
(ii) pH of the soil is less than 8.5 (<8.5)
(iii) ESP is less than 15 (<15)
(iv) SAR is less than 13 (<13)
Dominated by
Ca2+ and Mg2+
34

35. ပ ြေဆီလ ဆ ားပ ေါက် ြင်ား၏ အ င်အပ ေါ်သကက်ပက က်ြေ
❖ အဓကသက်ရရောက်မှု- အပင်မှရရစိုပ်ယူနိုင်မှုနည်ီး
❖ အသသောဆိုီးထခိုက်မှု - အစောချက်မှုရနှီးသွောီး။ အပင်ကကီီးထွောီးဖွွံ့ဖြိဖမီးမှုရနှီး။
❖ ရဖမကကီီးထဲရှရပျော်ရည်ဖပင်ီးအောီး (osmotic concentration) သည် ဆဲလ်အတွင်ီးရှ
ဆဲလ်ရဖျော်ရည်၏ဖပင်ီးအောီးထက် လွန်စွောမျောီးရနရသောရ ကောင် ပိုမှန်အတိုင်ီး ရရစိုပ်ယူမှု
ဖဖစ်ရမည်အစောီး အဖမစ်ဆဲလ်အတွင်ီးမှရရမျောီး အဖပင်သိုို့ ရဖပောင်ီးဖပန်စမ်ထွက်မှု (outward
osmosis) ဖဖစ်စဉ်ဖဖင် ထွက်သွောီးမည်ဖဖစ်ကော အပင်မှရရဆိုီးရှုီးမှုဖဖစ်ရစ။
❖ အပင်သည် ရရငတ်ဖခင်ီး (drought) ကိုခစောီးရ။
❖ အသောီးတင်ရရစိုပ်ယူနိုင်ရန် - ဆဲလ်အတွင်ီးရှရပျော်ရည်၏ဖပင်ီးအောီး > ရဖမကကီီးထဲရှရပျော်ရည်၏ဖပင်ီးအောီး
❖ ၎င်ီးရပျော်ရည်နှစ်ခို၏ ဖပင်ီးအောီး မကွောပါက အပင်မှ အသောီးတင်ရရစိုပ်ယူမှုရှမည်မဟိုတ်။
❖ ဆိုဒီယမ်ကလိုရိုဒ် (NaCl) တွင်ပါဝင်ရသော ဆိုဒီယမ် (Na+) သည်ရဖမကကီီး၏ တည်ရဆောက်ပိုကို
ပျက်စီီးရစနိုင်။
❖ ဆိုဒီယမ် (Na+) နှင် ကလိုရင်ီး (Cl-) နှစ်မျမီးစလိုီးသည် ဖပင်ီးအောီးမျောီးလျှင် အပင်အောီး
အဆပ်သင်ရစနိုင်။
35

36. 36

37. 37

38. 38
Management of saline soils
❖ Removing excess salt - leaching with water and drainage
❖ Sub-surface drainage is an effective tool for lowering the water table, removal of excess
salts and prevention of secondary salinization.
❖ Irrigation management
✓ Use of salt free irrigation water
✓ Irrigated more frequently.
✓ Sprinkler or drip irrigation is ideal
▪ Fertilizer management (Application of FYM, Use of acidic fertilizer)
▪ Crop choice / Crop management
✓ High salt tolerant crop- Sesbania, Barley, sugar beet, sugarcane
✓ Moderately salt tolerant crops- wheat, rice, sorghum, maize, cotton
✓ Low salt tolerant crop- Bean, radish, sesamum
✓ Sensitive crops- Tomato, potato, onion, carrot.
▪ Soil/cultural management
(Ploughing & levelling increases infiltration rate of the land. Thus salts leach down to the lower level.
Planting or sowing seeds in furrow)
sesbania

39. 2.1.2 ဆ ် ပ ေါက်ပ ြေ (Sodic soil) (Black-Alkali Soil)
▪ In arid and semi-arid regions, Ca2+ and Mg2+ - principal cations found in soil solution & on
exchange complex of normal soil
▪ When excess soluble salts accumulate in these soil, Na2+ become dominant cation in soil
solution
▪ When the solution becomes concentrated through evaporation or water absorption by
plant, Ca and Mg are precipitated as CaSO4, CaCO3 and MgCO3, with increasing of Na2+
concentration.
▪ When Na2+ concentration is more than 50% of the total cations a part of the original
exchangeable Ca2+ and Mg2+ replaced by Na2+ resulting in sodic soil.
39

40. (a) အရရောင် – အမည်ီးရရောင် (Usually black )
(b) ရိုပ်ပိုင်ီးဆိုင်ရော လကဖဏောမျောီး (Physical
Characteristics )
(i) တည်ရဆောက်ပို – အလွန်ည (Very poor)
(soil is in highly dispersed
condition)
(ii)ရရစမ်နိုင်စွမ်ီး (Infiltration rate) –
အလွန်ည (Very poor)
(iii) ရဖမကကီီး၏ ရလဝင်ရလထွက် (Soil
Aeration) – အလွန်ည (Very poor)
ဆ ် ပ ေါက်ပ ြေ (Sodic soil)
40

41. (c) ရူပ၊ဓောတို လကခဏောမျောီး Physicochemical Characteristics
(i) EC of the saturation soil extract is less than 4 dSm-1 (<4)
(ii) pH of the soil is more than 8.5 (>8.5)
(iii) ESP is higher than 15 (>15)
(iv) SAR is greater than 13 (>13)
High in exchangeable Na+
compared to by Ca2+ and Mg2+
41

42. Effects of sodicity
▪ dispersion in the soil surface, causing crusting and sealing, which then impedes water
infiltration
▪ dispersion in the subsoil, accelerating erosion, which can cause the appearance of gullies
and tunnels
▪ Due to dispersion, weakenss the aggregates - structural collapse & closing-off of soil pores
▪ Dispersion of soil colloids leads to development of compact soil
▪ Aeration, hydraulic conductivity, drainage and microbial activity are reduced due to
compactness of soil
▪ Excess Na+ induces deficiencies of Ca2+ and Mg2+
42

43. Soil clay particles can be unattached to one another (dispersed) or clumped together
(flocculated) in aggregates. Soil aggregates are cemented clusters of sand, silt, and clay
particles.
Dispersed Particles Flocculated Particles
43

44. Flocculation is important because water moves mostly in large
pores between aggregates. Also, plant roots grow mainly
between aggregates.
44

45. dispersed clays plug soil pores and impede water infiltration
and soil drainage.
45

46. Management of sodic soils
(a) Conversion
▪ Necessary to remove exchangeable sodium before removal of soluble salts.
▪ While removing exchangeable sodium, presence or absence of CaCO3 in soil had to be
taken into consideration.
▪ If soil has no reserve CaCO3, addition of CaSO4 (Gypsum) is necessary.
❖ Replace exchangeable Na by another cation calcium (Ca2+).
❖ Of all calcium compounds, gypsum (CaSO4.2H2O) - best & cheapest for reclamation
purpose.
▪ Calcium (Ca2+) solubilized from gypsum replaces sodium (Na+) leaving soluble sodium
sulphate (Na2SO4) in water, which is then leached out.
46

47. Gypsum requirement (GR)
▪ (GR) is expressed as meq of Ca2+ per 100 gm. soil.
▪ It is determined by laboratory analysis. In the absence of such an analysis,
recommended rates range from 3 to 5 tons per acre. The amount of water to
apply is that about 3 inches of water per acre will dissolve 1 to 2 tons of
gypsum
GR =
𝐸𝑆𝑃 𝑖𝑛𝑖𝑡𝑖𝑎𝑙 −𝐸𝑆𝑃 𝑓𝑖𝑛𝑎𝑙 𝑋 𝐶𝐸𝐶
100
ESP (initial) = analysis of soil before application of gypsum;
ESP (final) = usually kept at 10 (Since an exchangeable sodium percentage (ESP) of
10 is considered safe for tolerable physical condition of the soil)
CEC = cation exchange capacity in meq/ 100 g of the soil.
47

48. Management of sodic soils
(b) Other management practices
▪ Application of FYM, green manure, organic residues ,
▪ Acids or acid forming substances, e.g. Sulphur, molasses, aluminium sulphate
and sulphuric acid.
▪ Growing salt tolerant crops.
Grasses (more tolerant of sodic conditions than most field crops)
Rice as a reclamative crop
✓ The high pH of sodic soils is reduced under continuous flooding
✓ The low permeability of sodic soils is a further advantage to rice
because losses of water due to deep percolation are restricted
48

49. Management of sodic soils
(c) Prevention
▪ Avoid excess water table by following judicious water management
practices
▪ Ensure free and efficient drainage
▪ Flooding of land with large quantities of water must be avoided
▪ Evaporation should be checked as far as possible by mulching or by
providing proper shade
49

50. 50
ြေားက ပ ီား (သကို့)ပကသကွင်ားပ ီားပ ောက် ပ ြေပအ က်ပကြေျက်နော င် ြေင်တက်လ

51. 51
သကွင်ားပက ြင်ဆ ားြေျ ားပက က်ကလ

52. 2.1.3 ဆ ားဆ ် ပ ေါက်ပ ြေ (Saline-Sodic Soil)
❖ particularly in the arid and semi-arid regions, contain CaCO3 in the profile
(a) အရရောင် – အဖဖြူရရောင် (Usually white)
(b) ရိုပ်ပိုင်ီးဆိုင်ရော လကဖဏောမျောီး (Physical Characteristics )
(i) တည်ရဆောက်ပို (Soil Structure )– ရကောင်ီး (Good)
(ii) ရရစမ်နိုင်စွမ်ီး (Infiltration rate) – ရကောင်ီး (Good)
(iii) ရဖမကကီီး၏ ရလဝင်ရလထွက် (Soil Aeration) – ရကောင်ီး (Good)
52

53. (c) ရူပ၊ဓောတို လကခဏောမျောီး Physicochemical Characteristics
(i) EC of the saturation soil extract is higher than 4 dSm-1 (>4)
(ii) pH of the soil is lower than 8.5 (<8.5)
(iii) ESP is higher than 15 (>15)
(iv) SAR is greater than 13 (>13)
Management of saline sodic soils
The management practices were the same as sodic soil.
53

54. 2.2. Acid soil
Properties of acid soil
▪ Low CEC
▪ Intermediate texture (Sandy loam to Loam)
▪ Low organic matter content (except hilly region & forest soils, peat soil)
▪ Low P content but N is variable
▪ High amount of Fe and Al in soil solution
54
✓ Soil with low pH (below 7)
✓ contain relatively high amounts of exchangeable H+ & Al 3+
✓ occupy approximately 60 % of the Earth
Formation
➢ areas of high rainfall, poor drainage, heavy nitrogen fertilizer
use
➢ Humus decomposition
➢ Application of elemental sulphur (formation of H2SO4)

55. Different sources for formation acid soil
▪ Rain fall
▪ Parent materials
▪ Fertilizer application
▪ Plant root activity
▪ Decomposition of organic matter
▪ Export of farm product
▪ Vegetation cover
55

56. Rain fall
▪ Mostly found in excess rain fall areas
▪ Excess rain fall leaches base cation from the soil (Na, K,
Ca & Mg)
▪ Additionally rain water has a slightly acidic
✓ H2O+ CO2 H2CO3 H+ + HCO3
-
▪ Increase the percentage of H+ in soil
56

57. Burning of fossil fuels lead to the formation of acid
eg. H2SO4, HNO3
Humid region, soil acidification increase on global scale
(acid precipitation)
57
Contact with soil these acid rain rapidly break down soil
minerals as well as depressing soil pH (serious ecological
hazard)

58. Parent materials
▪ Many soils of the world are acidic (parent material weathering)
▪ The development of acid soil on acidic rocks like Granite, Gneiss, quartz, silica
▪ Materials eg. shale, sandstone & granite generally produce more acidic soils
▪ Overtime soils have a general tendency to become more acidic
58

59. Fertilizer use
▪ Repeated application of N fertilizer
▪ Most acidifying are ammonium sulfate, monoammonium phosphate (MAP) & diammonium
phosphate (DAP)
▪ Less acidifying are urea, ammonium nitrate & anhydrous ammonia
Figure. The main pathways showing
the involment of N fertilizers in soil
acidification
Nitrification
Nitrification produce H+
59

60. Plant root activity
▪ Plant uptake nutrients- both anion and cation
▪ Plant must maintain a neutral charge in their roots
▪ In order to compensate the extra positive charge they release the H+ ions
▪ Some plants roots produce the organic acid – acid soil
60

61. Export of farm product ➢ Plants absorb more cations than anions
(most plant material is slightly alkaline)
➢ In natural system, when plants die they
are decomposed and returned to soil,
balancing acidity caused by H+
➢ In agriculture, if plant material is
removed there is a net export of
alkalinity and residual H+ remain in soil
causing soil acidity
➢ Over time, as this process is repeated,
soil becomes acidic
Figure H+ added in the carbon cycle contribute to soil acidification 61

62. Acid soil
CO2 reacts with soil water can produce the carbonic acid.
Microorganism - release the CO2
Decomposition process requires the microorganism
Decomposition of organic matter
62

63. Vegetation cover
▪ Temperate region areas covered with conifers (acid
soil develop easily)
▪ Foliage of conifers lacks alkali substances
▪ Leaf-litter on ground is degraded, organic acids are
released (make the soil acid)
▪ Coastal region & marshy places, plants after the
death & decay produce acid which render the acidic
soil
63

64. Impact on soil properties
Physical
▪ Strongly acid soils - potential for reduced vegetation
▪ High permeability
▪ Poor water holding capacity
▪ Low pH soils are more loosely held together
▪ Soil losses due to water & wind erosion
▪ Degraded through external influences such as high rainfall events, drought
64

65. Chemical
▪ Low pH
▪ More anion fixing capacity
▪ Decrease the availability of P
▪ High % of base unsaturation
▪ Al toxicity is more
▪ Ca, Mg levels decrease (deficiency)
▪ Mo level decrease (deficiency)
▪ Restriction of nitrogen fixation in
legumes
65

66. Biological
▪ Low pH reduced growth of beneficial organisms
▪ Change in the microbial decomposition processes
▪ Fungi population is more than that of bacteria
▪ Fungi cause root disease
▪ Decreasing the survival of native vegetation
▪ Earthworms are unable to tolerate low pH (poorer soil structure & reduced organic
matter decomposition)
66

67. Management of acid soil
1. Application of liming materials (To neutralise soil acidity and
increases activity of soil bacteria)
Different liming material to reclamation of acid soil
• Carbonates - CaCO3 (ထိုီးရကျောက်)
• Oxides - CaO (မရဖောက်ထိုီး)
• Hydroxides - Ca(OH)2 (ရဖောက်ထိုီး)
• Silicate of calcium - CaSiO3
67

68. 68
The reaction of lime with acidic soil is represented by the following equations

69. ❖ lime should be mixed with the soil well ahead of planting
69

70. Figure. Particle size distribution & efficiency
Solubility and qualities of lime
▪ Lime is slowly soluble in water
▪ Effectiveness depends on purity of the liming material & how finely it is ground
70

71. Benefits
Figure. Distinct growth rate on same acid soil upon liming
❖ liming eliminates toxic Al3+ & H+
❖ lime will raise the soil pH
❖ supply Ca2+ & Mg2+
❖ formation of soil aggregates (improving soil structure)
❖ Crop yield improvement
❖ Nutrient availability
❖ Improved microbial activity
❖ Improved legume fixation
71

72. Before liming After liming
72

73. Lime requirement (ton/ha) =[(Al3+ + H+) – (CEC * 0.01)] * 2 = X
Lime Requirement (ton/ac) = X / 2.471
(1 ha = 2.471 ac)
LIME REQUIREMENT(LR)
▪ LR of an acid soil is the amount of a liming material that must be added to raise the
soil pH to a desired level. (usually in the range of 6.0 to 7.0)
▪ LR ranges from 3.5 to 15 t/ha.
Effects of over liming
▪ Deficiency of Fe, Cu, Zn, P, K
▪ Increment of OH- activity may cause root injury
▪ Over liming Boron deficiency occur
▪ Too much application of lime increase the pore space in the soil, soil dries up,
efficiency of water use is low
73

74. 2. Application of Crop residues
▪ Basic cations which are released during decomposition of crop residuces increase the
pH
▪ Soil pH changes after the addition of chickpea residues
▪ The greatest increase in soil pH occurred after chickpea addition as it is easily
mineralized
▪ Chickpea has a potential alkalinity
74

75. 3. Application of animal manures
Swine manure
Goat manure
Poultry manure
Cow manure
Reactions
✓ Organic manures mineralize, Ca
ions are released into soil solution
✓ Ca ions get hydrolysis process
✓ CaOH formed reacts with soluble Al
ions in the soil solution to give
insoluble Al(OH)3
Animal
manure
Ca Mg
Swine 1.37 1.30
Goat 1.37 0.83
Goat 1.24 0.89
Cow 1.12 1.94
Ano et al 2007
Chemical composition of animal manure
75

76. Other approach to acid soil
management
▪ use of acid-tolerant species
▪ efficient use of fertilizers
▪ suitable crop rotations
▪ crop diversification
Acid Soil Crops: prefer a pH of 4 to 5.5:
Tea (4.0 – 5.5)
Blackberry (5.0-6.0)
Blueberry (4.5-5.0)
Cranberry (4.0-5.5)
Peanut (5.0-7.5)
Potato (4.5-6.0)
Raspberry (5.5-6.5)
Somewhat Acid Soil Crops:
tolerate a pH of 5.5 to 6.5:
Apple (5.0-6.5)
Basil ပင်စမ်ီး (5.5-6.5)
Carrot (5.5-7.0)
Cauliflower (5.5-7.5)
Corn (5.5-7.5.)
Cucumber (5.5-7.0)
Dill ဇီယော (5.5-6.5)
Eggplant (5.5-6.5)
Garlic (5.5-7.5)
Melon (5.5-6.5)
Parsley နန (5.0-7.0)
Pepper ငရိုတ်ရကောင်ီး (5.5-7.0)
Pumpkin (6.0-6.5)
76
Radish (6.0-7.0)
Sweet potato (5.5-6.0)
Tomato (5.5-7.5)
Turnip မိုန်လောဥ (5.5-7.0)

77. Highly tolerant
▪ Strawberry
▪ Plum
▪ Radish
▪ Sweat potato
▪ Pepper
▪ Beans
▪ Cabbage
▪ Carrot
Moderately tolerant
▪ Pineapple
▪ Orange
▪ Litchi
▪ Jack fruit
▪ Onion
▪ Tomato
Slightly tolerant
▪ Mango
▪ Guava
▪ Cashew
Selection of crops
77

78. Soil acidity is a serious problem in agricultural land
improve soil health (various management practices)
Based on soil test value recommend the fertilizer
Judicious application of nitrogenous fertilizer
78

79. 3.1. Soil organic carbon (SOC) and microbial population
▪ SOC - main source of energy for soil microorganisms
▪ Humus participates in aggregate stability, and nutrient & water holding capacity.
▪ Organic acids (e.g., oxalic acid), commonly released from decomposing organic residues and
manures
▪ Poor SOC - reduced microbial biomass activity & nutrient mineralization due to a shortage of
energy sources.
▪ Low SOC results in less diversity in soil biota, which can cause disturbance in soil
environment (e.g., plant pest and disease increase, accumulation of toxic substances).
Biological Problem soils
Physical Problem soils
3. Biological Problem soils
79

80. Improving Carbon Levels
▪ Zero or minimum tillage
▪ Continuous application of manure and compost
▪ Use of summer and/or winter cover crops
▪ Avoid burning of crop residues
80

81. 3.2. Earthworms
▪ Key role - modifying physical structure of soils by producing new aggregates and pores,
which improves aeration, infiltration, and drainage.
▪ Produce binding agents responsible for the formation of water-stable macro-aggregates.
▪ Improve soil porosity by burrowing and mixing soil.
▪ As they feed, earthworms participate in plant residue decomposition, nutrient cycling and
redistribution of nutrients in the soil profile.
▪ Dead or decaying earthworms, are a source of nutrients.
81

82. Problems
▪ Low or absent earthworm populations - indicator of little or no organic residues in soil
▪ High soil temperature and low soil moisture that are stressful not only to earthworms,
but also for sustainable crop production.
▪ Earthworms stimulate organic matter decomposition.
Lack of earthworms
✓ Reduce nutrient cycling and availability for plant uptake.
✓ Reduce natural drainage and aggregate stability.
82

83. Improving Populations
▪ Tillage Management (no-till, strip till, ridge till)
▪ Crop Rotation (with legumes)
▪ Cover Crops,
▪ Manure and Organic By-product Application
▪ Soil Reaction (pH) Management (neutral pH is ideal, earthworms can adjust to pH
5–8 with some species tolerating even more acidic soils)
▪ Proper irrigation or drainage
83

84. 3.3. Soil Respiration (carbon mineralization)
✓ It is a measure of carbon dioxide (CO2) release from soil
✓ plays a critical role in the regulation of carbon cycling
✓ provides an indication of the soil's ability to sustain plant growth
✓ measure biological activity and decomposition.
This CO2 results from several sources,
❖ decomposition of soil organic matter and plant litter by soil microbes (microbial
respiration)
❖ plant root respiration,
❖ the dissolution of carbonates in soil solution.
84

85. Problems
Reduced soil respiration rates
✓ little or no microbial activity in soil.
✓ nutrients are not released from SOM to feed plants and soil organisms.
✓ This affects plant root respiration, which can result in the death of the plants.
▪ Incomplete mineralization of SOM often occurs in saturated or flooded soils, resulting in
formation of compounds that are harmful to plant roots (e.g. methane and alcohol).
▪ In such anaerobic environments, denitrification and sulphur volatilization usually occur,
contributing to greenhouse gas emissions and acid deposition.
Improving Soil Respiration
❖ Under favorable temperature and moisture conditions, rate of soil respiration is generally limited by
supply of SOM.
❖ Agricultural practices that increase SOM usually enhance soil respiration.
85

86. 86