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

SUMMARY
The Lluidas Vale survey area comprises about 11,000 ha in the northwestern
and central-southern part of the parishes of St. Catherine and St.
Ann respectively. The area is covered by topographical map sheets 84A and
84C. The soil map for the area is attached as Enclosure I. The mapping units
are delineated on the basis of physiography, lithology and soils, defined
according to USDA Soil Taxonomy at Series level.
The survey area lies in the Intermediate and Wet Moisture Availability Zone.
Yearly R75/PET values, in which R75 is rainfall reached or eiceeded in 75%
of the years and PET is potential evapo-transpiration, range from 0.76 to
1.15, which reflect favourable rainfall conditions for a wide range of
climatically adapted crops in most years. Rainfall in 80% of the years varies
from 857-1807 mm per year at the driest locations to 1313-2453 mm per
year at the wettest locations. The dependable growing period lasts from May
to December in the major part of the area. Mean temperatures range from
24-26'C at the lowest elevations (about 250 m above msl) to 17-20'C at the
highest elevations (about 900 m above msl).
The major landforms in the area are the Hills and Foothills (80% of the
survey area), the Inland Basins (15%) and the River Plains (2%). The Hills
and Foothills are hilly to steeply dissected, located in the northern, central
and south-eastern parts of the survey area. Lithologically they are mainly
related to limestone deposits. The Inland Basins consist of almost flat to
rolling Old Alluvial Deposits, also referred to as lacustrine deposits. The River
Plains consist of Recent Alluvial Deposits with almost flat to undulating
topography. The Old and Recent Alluvial deposits occur in two basins: the
Lluidas Vale basin in the south-west and the St. Thomas in the Vale, or
Linstead basin in the central-east of the survey area. Rural residential areas
occupy about 3% of the surveyed area.
Arable land comprises mainly the soils of the Lluidas Vale basin and the
Linstead basin. The soils over Old Alluvium generally are moderately well to
poorly drained and acid, which makes them suitable only for natural forest
and unimproved pasture at low management levels. At high management
and input levels, these soils are only marginally to moderately suitable for
most crops, due to persisting fertility problems (low nutrient availability,
high exchangeable aluminium contents) and/or physical problems (poor
ii