Nutrient element in rubber plantation
also lost by crop removal especially K and N
which are high concentration in rubber latex
(14,20). Along 25 lo 30 years of tapping
period, large amount of plant nutrient is lost
and should be compensated by adding
fertilizer. Slightly elevated the soil pH by
liming to reach a weak acid level should be
investigated for elevating available form of
some plant nutrient elements such as
phosphorus that is always fixed by Al and
Fe in acidic soil (26). At the same time the
soil will receive Ca which is the* most
necessary for bark or trunk development (19)
if CaCO. is used. Whereas if Dolomite is
added to adjust pH plant will receive both
Ca and Mg (27).
Economic life cycle of rubber tree is
around 30-40 years. That can be separated
into two phases; immature and tapping
phase. Well growth and healthy tree at
immature state can produce a high latex