crops and the economics of crop production. Moreover, the utilization of peatlands
should not result in environmental deterioration.
In view of their potential for agriculture, these soils have numerous problems that
greatly affect the crop performance. However, at present these problems still remain
unsolved. Research is needed in most reclaimed areas. The following constitute the
postulation of problems encountered.
Unfavorable Soil Characteristics According to the study, the constraints are
mainly attributed to some of the inherent soil properties. Physical problems include
a high amount of fiber and less decomposed woody fragments, high water holding
capacity, low bulk density, varying hydraulic conductivities, low bearing capacity,
low hydrophobicity upon burning and drying, and high combustibility. As a whole,
these undesirable properties result in poor root anchorage and serious problems for
drainage control. In addition, since marine deposits rich in pyrite underlay most of
the peat soils, these layers are subjected to oxidation upon rapid subsidence caused
by fire and peat decomposition, and thus giving rise to more adverse acidity and peat
shrinkage (Takai et al. 1987; Vijarnsorn and Takai 1992).
At the same time, the nutritional factors of the soil limiting crop growth can be
observed in most crops (Takai et al. 1987). These factors include (a) Low pH, high
Al, and low content of K, P, N, Cu, B, Zn, and Mn—low K constitutes the most
important factor, followed by low P and low N; (b) Among the micro nutrients, Cu
deficiency is the most critical, followed by the deficiency of B and Zn; and
(c) Organic substances such as phenolic compounds are considered to be toxic at
low pH and chelation of Cu and Fe.
Therefore, it should be noted that for crop production, these peat soils certainly
require liming and fertilizer application especially that of K, P, and N as well as other
trace elements. However, the rate of nutrient application should be suitable so it will
not incur nutrient imbalance to the crops. Furthermore, various physical data from
these soils should be used as the basic data for the installment of the drainage
scheme. It appears that the practical way to conserve peat is to maintain highest
possible water table to prevent shrinkage, low hydrophobicity or irreversible drying
and acidification. The water table should be at least above 80 cm to prevent oxidation
of pyritic mud clay which is concentrated mostly at the depth below 80 cm of the soil
surface.
Unfavorable Topography This problem occurs primarily due to physiographic
setting. Since most peatlands are located in depressions or in the low-lying topography, ergo the draining water from the areas is always an issue because some outlets
have to be opened to the sea, where sand bars commonly block the waterway.
Furthermore, the subsidence of the land surface and the collapse of the canal bank
create more problems for the drainage efficiency and maintenance.
Limitation of Crop Selection Although attempts have been made to grow various
crops in the peat soils, many of them have been proven unsuccessful. These crops
include rice, sweet potato, cassava, banana, sweet corn, and oil palm. During the first
year of the cultivation, the crop yield appeared to be quite satisfactory. However, a
744
P. Vijarnsorn
should not result in environmental deterioration.
In view of their potential for agriculture, these soils have numerous problems that
greatly affect the crop performance. However, at present these problems still remain
unsolved. Research is needed in most reclaimed areas. The following constitute the
postulation of problems encountered.
Unfavorable Soil Characteristics According to the study, the constraints are
mainly attributed to some of the inherent soil properties. Physical problems include
a high amount of fiber and less decomposed woody fragments, high water holding
capacity, low bulk density, varying hydraulic conductivities, low bearing capacity,
low hydrophobicity upon burning and drying, and high combustibility. As a whole,
these undesirable properties result in poor root anchorage and serious problems for
drainage control. In addition, since marine deposits rich in pyrite underlay most of
the peat soils, these layers are subjected to oxidation upon rapid subsidence caused
by fire and peat decomposition, and thus giving rise to more adverse acidity and peat
shrinkage (Takai et al. 1987; Vijarnsorn and Takai 1992).
At the same time, the nutritional factors of the soil limiting crop growth can be
observed in most crops (Takai et al. 1987). These factors include (a) Low pH, high
Al, and low content of K, P, N, Cu, B, Zn, and Mn—low K constitutes the most
important factor, followed by low P and low N; (b) Among the micro nutrients, Cu
deficiency is the most critical, followed by the deficiency of B and Zn; and
(c) Organic substances such as phenolic compounds are considered to be toxic at
low pH and chelation of Cu and Fe.
Therefore, it should be noted that for crop production, these peat soils certainly
require liming and fertilizer application especially that of K, P, and N as well as other
trace elements. However, the rate of nutrient application should be suitable so it will
not incur nutrient imbalance to the crops. Furthermore, various physical data from
these soils should be used as the basic data for the installment of the drainage
scheme. It appears that the practical way to conserve peat is to maintain highest
possible water table to prevent shrinkage, low hydrophobicity or irreversible drying
and acidification. The water table should be at least above 80 cm to prevent oxidation
of pyritic mud clay which is concentrated mostly at the depth below 80 cm of the soil
surface.
Unfavorable Topography This problem occurs primarily due to physiographic
setting. Since most peatlands are located in depressions or in the low-lying topography, ergo the draining water from the areas is always an issue because some outlets
have to be opened to the sea, where sand bars commonly block the waterway.
Furthermore, the subsidence of the land surface and the collapse of the canal bank
create more problems for the drainage efficiency and maintenance.
Limitation of Crop Selection Although attempts have been made to grow various
crops in the peat soils, many of them have been proven unsuccessful. These crops
include rice, sweet potato, cassava, banana, sweet corn, and oil palm. During the first
year of the cultivation, the crop yield appeared to be quite satisfactory. However, a
744
P. Vijarnsorn