This study was undertaken to investigate the stomatal density in leaflets of sago palm, a tropical starch crop, to gain some fundamental knowledge related to photosynthesis of the leaves. 1) To investigate the Stomatal density at different parts on leaflets attached to lower, middle and upper positions in one leaf, leaves on the lower, middle and upper parts of plants were sampled from the palms at trunk formation stage (about 5-years old) in a farmer’s sago garden in Tebingtinggi Island in Riau, Indonesia. The tip part of a leaflet had lower stomatal density than basal or middle part, and abaxial surface had higher stomatal density (550-750/mm²) than adaxial surface (100-250/mm²)．Stomatal density of both sides on a leaflet showed a tendency to decrease from base to tip part with the decrease in thickness. Little difference was observed in the stomatal densities among leaves and leaflets at different positions in a plant and in one leaf, respectively. 2) To investigate the change of stomatal density by palm age, leaflets on the middle position in leaves of middle part of 1- to 5-years old palms were sampled in a farmer’s sago garden in Muka, Sarawak, Malaysia. stomatal density of abaxial surface markedly increased from 1- to 3- years old (400-900/mm²)，however, it gradually increased thereafter and attained almost the definite value (1000/mm²) at 5-years old, trunk formation stage. In adaxial surface, the stomatal density also increased with aging of palms, but the density (50-120/mm²) is significantly smaller than that of abaxial surface (400-1000/mm²)，irrespective of palm age.

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 Chemical and physical characteristics of soils planted sago palm were analyzed to get information for improvement of cultural practices of sago. Soil samples were collected from Riau Indonesia, Johor and Sarawak Malaysia and Narathiwat Thailand, and divided into two main groups of soil; mineral and peat soils.
 The pH of the peat soils were around 4, which were lower than that of the mineral soils. Cation exchange capacity (CEC) of the peat soils evaluated at pH7 (CEC pH7) were about twice higher than that of the mineral soils. In the most of peat soils, CEC evaluated at pH4 (CEC pH4) were 70-90% of the CEC pH7. However, in the most of mineral soils, the CEC pH4 were more than 90% of the CEC pH7. These results imply that the peat soils performed a variable charge.
 Parameters for mineralization of soil organic N were computed by using Arrenius’ law and Michaelis-Menten’s equation. The apparent activation energy of the peat and mineral soils were 16500-17400 and 16000-24100 cal mol^-1, respectively. The mineralization rate of the peat and mineral soils were 0.034-0.067 and 0.023-0.028 day^-1, respectively.
 At 100 reference days of the soil incubation, the amounts of mineralized N under submerged conditions were 2.5-5.8 mg kg^-1 in the peat soils and 1.2-1.4 mg kg^-1 in the mineral soil. These amounts were calculated as weight basis. However, a very different value of bulk density between the peat and mineral soils was observed. Thus, the mineralized N and CEC expressed as volume basis are more practical to compare between the peat and mineral soils rather than weight basis. Amounts of mineralized N and CEC calculated as volume basis were only 20% of those calculated as weight basis. As a result, N mineralization and CEC calculated by volume basis indicated higher fertility of the mineral soil than the peat soil.

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