Soil Moisture and Porosity

Soil Moisture/Water Content, WC (%)

A total of 17 stratified samples were oven-dried. The mass of water loss is given by the mass difference between wet and oven-dried soil. The soil moisture content is the percentage of water loss in the wet soil.

Dry Bulk Density, ρ _db (g/cm³)

Using the same data of mass of oven-dried soil, dry bulk density is calculated as the fraction of mass of over dried soil of volume of wet soil.

Field Capacity, FC (%)

Water was added to stratified soil samples in cylinders that were covered and sealed with saran wrap to allow capillary action. Samples were oven-dried at 105C for 166 hours. Field capacity is calculated as the percentage of water loss of the oven-dried samples.

Hygroscopic Coefficient, HC (%)

A hygroscopic coefficient represents the amount of water in the soil that is completely inaccessible to plants and held by H-bonding at the molecular level. The vapour flow of water governs the movement of water at this point. The hygroscopic coefficient is calculated as the percentage of the difference in mass of dried and oven-dried soil samples.

Wilting Point, WP (%)

Live plant sample collected from the soil pit was revived and wilted at the lab. Wilting point is calculated as the percentage of water loss of the mass of oven-dried soil.

Porosity, θ

Porosity is the amount of void space within the soil. The value of porosity lies between 0 and 1; while 0 indicates no void space and 1indicated complete emptiness. Porosity is calculated as the ratio of the difference between dry bulk density and particle density and particle density.

Soil Texture

Pre-treatment of Soil Sample

A sufficient amount of hydrogen peroxide was added to the bulk soil sample and slowly brought to a boil to destroy organic material. 20mL of sodium hexametaphosphate (Calgon) solution was mixed with the soil samples for the pipetting analysis.

Grain Size Analysis Sieving Technique

Wet sieving is to washing the pre-treated soil samples with distilled water to separate the coarse fraction from the fine fraction. The coarse fraction was caught by the mesh while the silt and clay-sized particles were carried into the 1L cylinder.

The coarse fraction was oven-dried and sieved through a series of calibrated sized mesh from Phi size -4.0 to +4.0.

Grain Size Analysis Pipetting Technique

20mL of fine fraction and Calgon solution was extracted from the well-mixed 1L solution at a precise time and depth of a chart calculated based on the sedimentation principle. The solutions were oven-dried to give the mass of particles of Phi sizes between +4.0 to +9.0.

Soil pH values

Soil pH values are determined using the Hellige-Truog soil reaction (pH) tester. two drops of indicator solution were used to moisten the soil samples and the reactant powder was used to completely cover with moist soil samples. Colours were compared with the Truog soil reaction and lime chart.