Environmental Engineering Reference
In-Depth Information
Soil Texture
Soil texture (% of sand, silt and clay) in the investigated area was analyzed by the
hydrometer method described by Huq and Alam (2005) modified from Bouyoucos (1962).
Moisture
Soil moisture was determined by weighing the air dried sample and the sample that was
oven dried at 105ºC for 24hrs to a constant weight. The following formula was used to
calculate the soil moisture of the investigated area.
(
W
2
W
1
100
% moisture=
W
2
Where W1 = Amount of oven dried sample
W2 = Amount of air dried sample
Field Water Capacity
To determine the field capacity of soil, samples were air-dried and crushed in a mortar
using pestle. Thereafter a known amount of sub-sample was weighed, saturated with water
and drained excess water for 48 hours. Then the following formula was used to find the out
field water capacity of the experimental field.
(
W
2
W
1
100
Field water capacity (%) =
W
1
Where W1 = Amount of air-dry soil.
W2 = Amount of soil saturated with water.
Bulk Density
The bulk density of soil was determined by core method described by Blake (1965a)
using a mass balance and cylinder. Labeled cylinders of predetermined volumes and weights
were used to collect soil samples from sampling stations. The soil within the cylinders was
held intact and taken to the laboratory for analysis. The soil-in-cylinder was then oven dried
at 105ºC till constant weight was achieved. Thereafter, oven-dry soil volume and weight were
determined. Values obtained were then used as inputs for the equation viz:
Wo .
d
Bulk density (Db) =
V
Where, Wo.d = Oven-dry weight of soil filled in core sampler.
V = Volume of the sample.
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