with NaOH (500 mol/m
3 ), brought to pH¼1 with HCl concentrated, and soluble
organic material (fulvic acid).
The organic substance plays a role in the buffering of the metal protons and
cations in the soil solution. The buffering phenomenon is performed by cation
exchange. The cationic exchange capacity of soil humus is the maximum number
of moles of dissociated protons in the humus mass unit under the given conditions of
temperature, pressure, soil composition, and humus concentration (Collado et al.
2018).
4.3.2.3 Soil Water
Soil water is considered to be water that is discharged from the soil sample by
maintaining it at 105
C at least 24 h. Water that is bonded to the soil mineral
structure (crystallization water) is not released under these conditions and is not
considered soil water. Also, a distinction is made between soil water and deep water,
the second being groundwater. Soil water is mainly found as a condensed phase in
the soil, although the water vapor content in the soil can be 30 mL/L in a damp soil.
Soil water is a landfill for dissolved gases and solids and is therefore the soil solution.
Dissolved solids that dissociate into ions (electrolytes) in the soil solution are the
most important for soil chemistry. Chemical elements whose ions are in uncontaminated soil solutions below 1 mmol/m
3 are called microelements and all others are
macroelements (Wiatrowska and Komisarek 2019).
4.3.2.4 Soil Atmosphere
The air that exists in the soil is constantly changing with the atmosphere above
it. The composition of the soil air is of the same type as atmospheric air (78% N 2 ,
21% O 2 , 1% Ar, 0,03% CO 2 ), but due to soil biological activity coupled with low
exchange rate, the percentage composition of soil air may differ considerably from
that of atmospheric air. For example, with regard to atmospheric air, the oxygen
content in the soil air is lower and that of CO 2 is higher. Under anaerobic conditions
(low oxygen content), the activity of MOs can produce significant amounts of NO,
N 2 O, NH 3 , CH 4 , and H 2 S. Dissolving gas from soil air into the soil solution is an
important process contributing to the cycle of chemical elements in the soil environment (Niklaus et al. 2016).
4.4
Soil Degradation
Soil degradation has high priority recently admitted by the European Environment
Agency. The physical characteristics of the soil can be affected by different soil
management practices: irrigation, sewerage, and sanitation, leading to degradation.
The soil degrades through erosion, desertification (desert emergence), and
salinization.
90
M. Butu et al.
3 ), brought to pH¼1 with HCl concentrated, and soluble
organic material (fulvic acid).
The organic substance plays a role in the buffering of the metal protons and
cations in the soil solution. The buffering phenomenon is performed by cation
exchange. The cationic exchange capacity of soil humus is the maximum number
of moles of dissociated protons in the humus mass unit under the given conditions of
temperature, pressure, soil composition, and humus concentration (Collado et al.
2018).
4.3.2.3 Soil Water
Soil water is considered to be water that is discharged from the soil sample by
maintaining it at 105
C at least 24 h. Water that is bonded to the soil mineral
structure (crystallization water) is not released under these conditions and is not
considered soil water. Also, a distinction is made between soil water and deep water,
the second being groundwater. Soil water is mainly found as a condensed phase in
the soil, although the water vapor content in the soil can be 30 mL/L in a damp soil.
Soil water is a landfill for dissolved gases and solids and is therefore the soil solution.
Dissolved solids that dissociate into ions (electrolytes) in the soil solution are the
most important for soil chemistry. Chemical elements whose ions are in uncontaminated soil solutions below 1 mmol/m
3 are called microelements and all others are
macroelements (Wiatrowska and Komisarek 2019).
4.3.2.4 Soil Atmosphere
The air that exists in the soil is constantly changing with the atmosphere above
it. The composition of the soil air is of the same type as atmospheric air (78% N 2 ,
21% O 2 , 1% Ar, 0,03% CO 2 ), but due to soil biological activity coupled with low
exchange rate, the percentage composition of soil air may differ considerably from
that of atmospheric air. For example, with regard to atmospheric air, the oxygen
content in the soil air is lower and that of CO 2 is higher. Under anaerobic conditions
(low oxygen content), the activity of MOs can produce significant amounts of NO,
N 2 O, NH 3 , CH 4 , and H 2 S. Dissolving gas from soil air into the soil solution is an
important process contributing to the cycle of chemical elements in the soil environment (Niklaus et al. 2016).
4.4
Soil Degradation
Soil degradation has high priority recently admitted by the European Environment
Agency. The physical characteristics of the soil can be affected by different soil
management practices: irrigation, sewerage, and sanitation, leading to degradation.
The soil degrades through erosion, desertification (desert emergence), and
salinization.
90
M. Butu et al.