Abstract
The present study performed to investigate the changes of weather, planting pattern and water amount used at zone level for five years of 2000-2004 and to find the actual condition of water utilization from the correlation between those changes in open ordinary field irrigation zone, as a study case, in Hokuso-toubu irrigation project area, Chiba prefecture, where the field irrigation system had been applied for 25 years. And the nice condition of available moisture for normal growth and the appropriateness of elements for irrigation design in this study zone were verified by judging the five years changes of TRAM remainder at zone level computed under irrigation and non-irrigation. Consequently, the suitability to the open ordinary field zone of irrigation design of our country as well as this study zone was verified, too.
