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Tree growth rate is the most important variable in commercial forestry because most of
the important management decisions are taken on the growth rate of trees. There are a
number of factors controlling the distribution and growth of teak. The important factors
are rainfall/soil moisture, temperature, light, geological formation and soil conditions. To
investigate factors affecting growth rate on teak plantations, Climatic and soil factors
were analysed on two teak monoculture plantations located in Monaragala and Puttalam
districts which are two different geographical areas in Sri Lanka. Sixteen permanent
sample plots which were demarcated on 2009 in both plantations were used and the
growth parameters, i.e., height and diameter at breast height were measured. To assess the
soil conditions in both plantation, undisturbed soil samples were taken from each
permanent plot and soil pH, total Nitrogen content, Phosphorous content, Potassium
content, Calcium content and Magnesium contents were measured as chemical analysis.
Soil bulk density, soil water holding capacity and soil textures were analysed as physical
tests. Geographical area is highly effect on growth rate of teak with result of the growth
comparison in two plantations. There is no straight line relationship between growth and
climate conditions in both plantations. The significant differences of soil conditions
between plantation and within plantation were identified. Soil pH range varies within
5.765±0.005 to 6.651 ±0.039 in both plantation is the best pH condition for the teak
plantations. Mean water holding capacity of Puttalam (27.669±1.460%) is lower than the
Kumaragama (32.215± 1.570%) plantation, mean soil bulk density in Puttalam
(0.34713±0.0 1681 gcm') is higher than the bulk density .in Kumaragama
(0.32275±O.O 1299 gcm'), mean soil Magnesium content in Puttalam (4.276±0.44 ugml')
is higher than Magnesium content in Kumaragama (4.1483±0.22 - ugml"), mean
Phosphorus content in Kumaragama (7.58±4.64 ppm) is higher than Phosphorus content
in Puttalam (6.3 I±5.32 ppm) and mean Nitrogen content in Puttalam (2.925± 1.360 ppm)
is higher than Nitrogen content in Kumaragama (1.450±0.366 ppm). These significant
differences or soil conditions between two plantations can hjghly influence on teak
growth rates in Puualarn and Kumaragama. Particularly, the higher WHC and lower SO
of Kumaragama plantation may influence for growth difference of two plantations.
