Abstract:
All of the tea plantations in Iran are concentrated in the Caspian Sea region on soils
previously developed under deciduous natural forests. This research conducted to study
the effect of land use change (from forest to tea) on selected physico-chemical and
mineralogical properties of soils under humid climate and mountainous landscape in
Northern Iran. Three transects facing west to northwest in both tea plantation and the
nearby natural forest were selected. A total of 18 soil profiles formed on different
physiographic positions i.e. summit, shoulder and foot slope were studied and
morphological features of the soils were described. Soil samples taken from each horizon
were analyzed. A two factor completely randomized design was used to take soil samples
from surface horizons in each transect. Results showed that after changing forest to tea
cultivation pH, cation exchange capacity, clay content and the amount of organic carbon
of the soils were decreased at P< 0.01 significance level, but bulk density was increased
compared to soils under natural forest. X-ray diffractograms of clay fractions showed
that vermiculite, vermiculite–illite mixed layers and hydroxy interlayered clay minerals
were the major clay components. Soils under tea cultivation possessed highly developed
and more prominent argillic horizons and contained more clay fraction in the lower
horizons in all physiographic positions.
Keywords: Forest soils, Land use change, Soils of Iran, Tea cultivation.
