There is an irrigation pond
for a circular irrigation system near the drainage canal outlet of
the A10 site
The irrigation period is usually from April to August
and the rice-growing season is from April to September
Crops such as onions and sweet potatoes are cultivated in the vegetable field throughout the year
Commercial pig production takes place inside pig barns with an
approximate pig density of 30 head ha1
within A10 in 2002. Livestock wastes were stored in earthen waste storage ponds as a standard disposal method until November 2004
After that time, the use of livestock wastes as manure has
been promoted and the earthen waste storage ponds are unused
estimated the annual nitrogen input in
2002 to be approximately 600 kg N ha1
(livestock waste, 79.9%;
fertilizer, 15.2%; precipitation, 2.2%; human waste, 1.8%; and irrigation water, 0.9%).
The topography is a shallow walled valley with
maximum and minimum heights from the mean sea level of 34
and 9 m, respectively.
Drainage canal slope near the outlet was
in the range of 1/2001/250. The soil type of A10 is mainly Andosols (volcanic ash) on clay bed
The study area located
in the Pacific side has a temperate climate with rainy season in
June and with typhoon season in September and October.