Purwanto et al. (2002) applied the slow-release N fertilizer to 4-year-old sago
palms grown in the peat soils of Riau, Indonesia and Sarawak, Malaysia, and studied
their growth. He did not find the difference between the fertilized and unfertilized
groups relevant to the palm height, the number of leaves, and the leaf N concentration in the fifth and 17th months of the commencement of application. However, the
leaf N concentration was found to be significantly higher in the 23rd month. Ando
et al. (2007) examined the application of nitrogen (N) (urea), phosphorus
(P) (phosphate rock), potassium (K) (potassium chloride), calcium (Ca) (phosphate
rock, dolomite), and magnesium (Mg) (magnesium chloride, dolomite) to sago
palms every 4 months from the time of being planted on the thick peat soil layer
(>3 m) at the peatland of Riau, Indonesia. In their experiment, the chemicals were
applied in the following quantities: 0.47 kg N/plant/year, 0.57–0.73 kg P 2 O 5 /plant/
year, and 2.4 kg K 2 O/plant/year. As the result, there was no effect of fertilization on
either palm height or the number of leaves in the five-year-old sago palms. Considering this information, it was suspected that nutrient deficiency might be accounted
for the delay of growth stage in the thick peat soil. Furthermore, Kakuda et al. (2000)
surmised that the reduced nitrogen mineralization per unit volume supplied by peat
soils was the reason for slower growth of sago palms in the peat soil when compared
to that in the mineral soil. The amount of ammonium nitrogen released from peat
soils through mineralization on the 50th day of incubation was approximately
5.8 mg/kg in Tebing Tinggi, Indonesia and 4.7 mg/kg in Mukah, Malaysia (Kakuda
et al. 2000).
Kakuda et al. (2005) applied approximately seven times of the usual amount of
macro- and micro-nutrients (N (urea), P (phosphate rock), K (potassium chloride),
Ca (phosphate rock, dolomite), Mg (dolomite), copper (Cu) (copper sulfate), zinc
(Zn) (zinc sulfate), iron (Fe) (iron sulfate), and boron (B) (borate)) twice on 5-yearold sago palms growing in a thick peat soil layer (over 3 m depth) of Riau, Indonesia
(peatland area) and monitored their growth for 16 months. The sago palms in the
fertilized plot were found to have higher dry matter weights of the petiole and sucker
than those in the unfertilized plot, but the dry matter weight of other organs (leaf
blade, rachis, and trunk) showed no change. These results demonstrated that fertilizer application increased the dry matter weight of the suckers rather than the parent
palm (Kakuda et al. 2015). Watanabe (2015) also discovered that the growth of sago
palms was not promoted appreciably under the normal fertilization regime but in a
plot where NPK derived from urea, rock phosphate, and potassium chloride was
applied at 10 times of the normal rate, the plant height tended to be taller by 20%.
The effects of micro-nutrients such as Cu and Zn application were also studied by
Nitta et al. (2000, 2003). Their tests on the suspected deficiency of Cu and Zn were
done on sago palms growing in the peat soil of Riau, Indonesia and they found that
the application of Cu (copper sulfate) and Zn (zinc sulfate) fertilizers for 6–30 months increased the leaf Cu and Zn contents. Yamaguchi et al. (1994) reported
that 8-year-old sago palms growing in thick peat soil layers (over 1.5 m depth)
showed a lower copper (Cu) content in the leaf and the trunk than those growing in
the mineral soil and suggested that this difference was one of the reasons inhibiting
their growth in the thick peat layers. Physiological impairments are sometimes
17 Sago Palm in Peatland
497
palms grown in the peat soils of Riau, Indonesia and Sarawak, Malaysia, and studied
their growth. He did not find the difference between the fertilized and unfertilized
groups relevant to the palm height, the number of leaves, and the leaf N concentration in the fifth and 17th months of the commencement of application. However, the
leaf N concentration was found to be significantly higher in the 23rd month. Ando
et al. (2007) examined the application of nitrogen (N) (urea), phosphorus
(P) (phosphate rock), potassium (K) (potassium chloride), calcium (Ca) (phosphate
rock, dolomite), and magnesium (Mg) (magnesium chloride, dolomite) to sago
palms every 4 months from the time of being planted on the thick peat soil layer
(>3 m) at the peatland of Riau, Indonesia. In their experiment, the chemicals were
applied in the following quantities: 0.47 kg N/plant/year, 0.57–0.73 kg P 2 O 5 /plant/
year, and 2.4 kg K 2 O/plant/year. As the result, there was no effect of fertilization on
either palm height or the number of leaves in the five-year-old sago palms. Considering this information, it was suspected that nutrient deficiency might be accounted
for the delay of growth stage in the thick peat soil. Furthermore, Kakuda et al. (2000)
surmised that the reduced nitrogen mineralization per unit volume supplied by peat
soils was the reason for slower growth of sago palms in the peat soil when compared
to that in the mineral soil. The amount of ammonium nitrogen released from peat
soils through mineralization on the 50th day of incubation was approximately
5.8 mg/kg in Tebing Tinggi, Indonesia and 4.7 mg/kg in Mukah, Malaysia (Kakuda
et al. 2000).
Kakuda et al. (2005) applied approximately seven times of the usual amount of
macro- and micro-nutrients (N (urea), P (phosphate rock), K (potassium chloride),
Ca (phosphate rock, dolomite), Mg (dolomite), copper (Cu) (copper sulfate), zinc
(Zn) (zinc sulfate), iron (Fe) (iron sulfate), and boron (B) (borate)) twice on 5-yearold sago palms growing in a thick peat soil layer (over 3 m depth) of Riau, Indonesia
(peatland area) and monitored their growth for 16 months. The sago palms in the
fertilized plot were found to have higher dry matter weights of the petiole and sucker
than those in the unfertilized plot, but the dry matter weight of other organs (leaf
blade, rachis, and trunk) showed no change. These results demonstrated that fertilizer application increased the dry matter weight of the suckers rather than the parent
palm (Kakuda et al. 2015). Watanabe (2015) also discovered that the growth of sago
palms was not promoted appreciably under the normal fertilization regime but in a
plot where NPK derived from urea, rock phosphate, and potassium chloride was
applied at 10 times of the normal rate, the plant height tended to be taller by 20%.
The effects of micro-nutrients such as Cu and Zn application were also studied by
Nitta et al. (2000, 2003). Their tests on the suspected deficiency of Cu and Zn were
done on sago palms growing in the peat soil of Riau, Indonesia and they found that
the application of Cu (copper sulfate) and Zn (zinc sulfate) fertilizers for 6–30 months increased the leaf Cu and Zn contents. Yamaguchi et al. (1994) reported
that 8-year-old sago palms growing in thick peat soil layers (over 1.5 m depth)
showed a lower copper (Cu) content in the leaf and the trunk than those growing in
the mineral soil and suggested that this difference was one of the reasons inhibiting
their growth in the thick peat layers. Physiological impairments are sometimes
17 Sago Palm in Peatland
497