Semi-detailed Soil Survey of the LIuidas Vale Area, St. Catherine-St ...

MATERIALS AND METHODS
selected on map sheet 84C, two of which were located in the hills and two in
the inland basin. These sample areas were expected to show the majority of
the soils and their physiographic relations. The location of the sample areas
is indicated in Figure 1. The toposheets 84A and 84C (1:12,500) were used as
field maps; the boundaries of the API units and sample areas were manually
transferred to these maps.
The slope map was prepared from a 1:25,000 copy of the base map; the
areas of different slope classes were identified with the help of a transparent
sheet on which the distances of the contour lines were indicated at 2, 5, 8,
16, 30 and 50% slopes, the so-called slope-ruler.
The base map for the final soil map at scale 1:25,000 was prepared from the
reduced toposheets 84A and 84C From the reduced map, a sepia copy was
derived through Xerox, after which another copy was prepared at sepia film.
The soil boundaries were drawn on this sepia film copy, so that the final soil
map has a subdued background of the topographical features.
3.2 FIELD PROCEDURES
The field work was carried out mainly in two periods: June 1986 and late
1988/early 1989. The majority of the observations for map sheet 84C and all
for map sheet 84A were done in the latter period.
Auger borings and profile pits were used for the characterization of the
various soils. In the sample areas auger observations were done along
transects and the remaining observations were made according to the "free
survey" technique. A total of 263 observations was made (on average: 1
observation/42 ha, with about a double density of observations in the inland
basins).
A total of 30 profile pits was described, 22 of which are presented in this
report. These 22 pits are the best representatives of the identified soil series,
and have complete soil description and analytical data. Each pit was 1 m by
1.5 m wide and 150 cm deep or to the bedrock, whichever was shallower.
The soils are described according to the Guidelines for Profile Description
(SSU 1989a), partially based on the Guidelines from FAO (1977). The colour
notation is according to the Munsell Soil Color Charts (Munsell 1975). From
each horizon described, a bulk sample was taken for chemical and textural
analyses. Samples from selected horizons were taken for moisture
availability determination. An additional set of samples was taken from each
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