8.1.3. Chemical characteristics

The results of the chemical analyses indicate that they are strongly acidic reaction soils with pH values between 4.7 and 5.3 with restrictions for K and Mg, whose Potencial De Hidrógenos (pH) is extremely low; they have medium to high values of S and high values of matter organic of soil (MO) and N, with MO being responsible for the CIC due to the low presence of clays. They do not contain aluminum contents that represent a toxicity hazard for many plant species.


Table 2. Profile no: VS24262 internal profile features.

The physical-chemical dynamics of this soil is controlled by the presence of allophane, caused by the alteration of volcanic ash; this component has an affinity for humus, and establishes with it strong bonds that result in the accumulation of organic matter in the soil.

results obtained indicate coarser textures (sandy and sandy loam) due to difficulties that arise in the analysis by interference of the allophone. The structure is in subangular, thin, and moderately developed blocks. The porosity is high, (56.43 and 60.39%) for horizons A and Bb, respectively, with a large predominance of macro pores. The apparent density presents low values, normal for soils derived from volcanic ash. The conditions of aeration and drainage are good. The consistency is friable, not plastic, and not sticky in the described

Figure 1 illustrates the moisture contents (%) and the soil moisture tension (Bars), information that indicates that as the soil tension increases, the moisture content decreases and what is related in this measure when the tension is zero (0) the ground is at the point of saturation. Such soil water behavior is evident for both horizons: A and Bb. The humidity retention is high at different stresses as a probable result of the presence of allophane and high levels of organic

horizons.

matter.

8.1.5. Humidity retention

Reference Horizon Altitude

Reference Horizon Altitude

Reference Horizon Altitude

Table 3. Physical properties VS24262.

SV24262- A

SV24262- Bb

SV24262- A

SV24262- Bb

SV24262- A

SV24262- Bb

(m)

Reference Horizon Humidity retention

(m)

(m)

Bulk density (g/cm<sup>3</sup> )

Sieve (#10) (2 mm) (%)

Stability index

Real density (g/cm<sup>3</sup> )

A 2444 1.05 2.41 56.43 24.25 13.25 18.93 11.42

Bb 2444 1.01 2.55 60.39 43.84 6.81 9.74 13.33

CG24262-A A 85.30 69.95 34.12 33.48 31.04 27.91 23.34 20.07 PL24262-C C 27.53 22.57 11.01 10.80 10.02 9.01 7.53 6.48

A 2444 87.8 3.48 2.88 1.48 4.36

Bb 2444 92.8 1.52 3.36 1.24 1.08

State aggregation

A 2444 0.08 5.10 94.16 145.51 3,041,010

Bb 2444 0.06 5.33 97.68 138.90 626,831

Sieve (#20) (0.84 mm) (%)

DPM (mm) Total porosity (%)

The Humidity of the Volcanic Soils and Their Impact on the Processes of Mass Removal in Colombia

Macro (%)

Saturation (%) 0.1 b 0.3 b 1 b 3b 5b 10 b 15 b

Sieve (#35) (0.5 mm) (%) Meso (%)

Sieve (#60 ) (0.25 mm) (%)

Hydraulic conductivity

(K) (mm/h)

Micro (%)

http://dx.doi.org/10.5772/intechopen.80399

Dispersión coefficient (%) 101

Sieve (#>60) (<0.25 mm) (%)

Moisture of threat (m<sup>3</sup> )

The humus-allophane interaction gives the soil particular properties such as high porosity, high water retention, and high capacity for nutrient retention (CICA); however, most of the electrical charge is not available to retain nutrients at the soil pH; this load only appears when the pH rises, such as occurs when the floors are limed. The load, which depends on the pH, is called variable load (CICV) and is the one that is present in this soil. A feature that distinguishes soils of volcanic origin, due to the presence of allophane, is the low availability of phosphorus; however, the analytical results of this soil show average contents of this element, undoubtedly due to the presence of apatite in volcanic materials.
