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第二章 土壤的基本性质 ( Soil basic characteristics ) PowerPoint PPT Presentation


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第二章 土壤的基本性质 ( Soil basic characteristics ). §2- 1土壤酸碱反应. §2-2 土壤交换吸收性能. §2-3 土壤养分. §2-4 土壤的结构性与孔隙性. §2-5 土壤的通气性. §2-6 土壤热状况. § 2-1 土壤的酸碱反应. 土壤酸碱性反应 我国土壤的酸碱性反应,大多数在 pH4.5~8.5 之间。在地理分布上有 “ 东南酸西北碱 ” 的规律性。大致可以长江为界(北纬 33  ),长江以南的土壤为酸性或强酸性,长江以北的土壤多为中性或碱性。我国土壤的酸碱性南北差异很大。. 活性酸度

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第二章 土壤的基本性质 ( Soil basic characteristics )

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Soil basic characteristics


2-

2-2

2-3

2-4

2-5

2-6


2-1


pH4.5~8.533


Active acidity

Exchangeable acidity

Soil acidity

Potential acidity

Hydrolytic acidity

Soil acidity

H+H+Al3


active acidity

H

pHpHlg [H]


potential acidity

HAl3H

1kg cmolcmol(H+)/kg cmol(+)/kg


H

+ KCl

K

+ HCl

K

K

K

Al

+ 3KCl

+ AlCl3

AlCl3+3H2O Al(OH)3+3HCl

1. (exchangeable acidity)

1mol/L KClNaClH+Al3


CH3COONa+H2O CH3COOH+NaOH

Na

NaNa

Na

Al

+ 4CH3COONa

+ Al(OH)3+4CH3COOH

H

2. (Hydrolyticacidity)

1mol/L NaOAcH+Al3



pH


CO2H+

(NH4)2SO4KCl


Soil basicity/alkalinity

NaNaNaCO3NaHCO3OH-

1pH

2

CO32- + HCO3- [cmol(+)/L]


100

3degree of alkalisation

510

1015

1520

>20


1.


  • pH6.5

  • NKS

  • PpH67pH<5pH>7


  • CaMgpH6.58.5

  • FeMnCuZnMopH>6

  • BpH6.07.0pH>8


2.

  • pH<5.5

  • pH

3.

  • H+Na+


4.


Soil buffer power

pH

pH


H

H

M

+ n H+

+ Mn+

+ H2O

H

+ MOH

H

1.


R-CH-COOH + NaOH = R-CH-COONa

NH2 NH2

R-CH-COOH + HCl = R-CH-COOH

NH2 NH3 Cl

2.

H2CO3 + Ca(OH)2 = CaCO3 + 2H2O

Na2CO3 + 2HCl = H2CO3 + NaCl

3.

()()


4.

pH<4Al3+OH-

Al3+H2OOH-H2OH+OH-AlOH-H2O

2[Al(H2O)6]3++2OH- [Al2(OH)2(H2O)8]4++4H2O

pH>5Al3+OH-AlOH3


1.pH

2.


1

g/m2 )=*1**28*1/1000


2

50g/150/0.51pH

3


2-2


1100 nm

1000 nm1m


(inorganic colloids)

(organic colloids)

(organo-mineral complex)


1:1

Kandites

Smectite

2:1

Hydrous Mica

Vermiculite




1.

/



1mm

2mm

226

24 mm2

1168

48 mm2


1.

2.

1(permanent/inner charge)

pH


  • 2 variable charge

  • OH

pH


colloidal sol

gel

1.

2.

3.


KKK

Ca

+ Ca2+ + NH4+

+ 3K+

NH4

K+

K+


1.

1Reversible reaction

2 Equal charge

1 mol Ca2 2 mol NH4+

3 Mass action law


2.

Fe3+ Al3+H+Ca2+Mg2+NH4+K+Na+

1

X3+>X2+>X+


2

(H+)

3


3.

(Cation exchange capacityCEC)

pHkg cmol/kg cmol(+)/kg

CEC

>20cmol(+)/kg

2010cmol(+)/kg

<10cmol(+)/kg


1

CEC

2

>

2:1>11>

3pH

pHHCEC


4. (Base saturation percentage)

K+Na+NH4+Ca2+Mg2+

(Bases)K+Na+NH4+Ca2+Mg2+

Acidic ionsH+Al3+


pH

pH

>80%

50%~80%

<50%


1H2PO4- HPO42-PO43-HSiO3-SiO32-C2O42-

2Cl-NO3- NO2-

3SO42-CO32-HCO3-CH3COO-


1(OH-)

OH->PO43->SO42->NO3-Cl-

2

3pHpH


1.

Na

Ca

2.


CECKK


2-3




leaf transpiration

precipitation

irrigation

evaporation

surface run-off

surface run-off

soil

ascending of groundwater

leakage

(/evapotranspiration):


  • 2.

  • 3.

  • 4.

  • 5.


  • 2.

  • 3.

  • 2.

  • 3.


2-4

2-4soilporosity structure


soil porosity

1. particle density

soil specific gravity

2.65


2. soil bulk density

1g/cm3t/m3

1.141.26g/cm3

  • 2


3.


1


1.

dmm

S100Pambar


2.

  • inactive pore

  • d<0.002mmS>1.5105 Pa

  • capillary pore

  • 0.002mm <d<0.02mm1.5105 Pa>S>1.5104 Pa

  • aeration pore

  • d >0.02mmS<1.5104 Pa


100g100cm3240g1058h220g




  • blocky

2. subangular

3. columnar


  • platy 1-5 mm

  • spheroidal0.2510 mm <0.25 mm

  • 2-3mm


  • 13 mm<0.25 mm




2-5



1. soil air diffusion

FD dcdx

F

D

dcdx

O2CO2soil respiration


2.


1.

2.

3.

4. O2CO2


1.

CO2O2

11

1. ODR

1mincm2gg/(cm2min)


3.

CO2O2mL/(cm3s)

4.

10-20

5.



[]ne []

soil redox potentialEh

VmV

E0

pH

n


O2-

EhEh


2-6


1

1.9 cal/cm2/min

2.

3.


34

100

47

19

E

23

14

10

Q2

Q1

Q3

Q


Soil heat capacity

1K

CJ / (gK)

CvJ / (cm3K)

Cv=Cd

C(Cv)



Soil thermal conductivity,

1cm1K

1cm2

J / (cmKS)


Soil temperature conductivity

cm1KS1cm21cm3

K= /Cvcm2/s



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