Simple Model of Soil Water Balance in Arabica Coffea cv. Catimor

Abstract

Soil Water Balance  of Coffea arabica cv. Catimor was conducted at Khun Chang Kian Highland Agriculture Station, Faculty of Agriculture, Chiang Mai University. The model of soil water balance using MBASIC computer programme to predict water used of plant and to compared with actual water used by drainage type lysimeter was determined. This study has been divided into two phases namely; rainy season and dry season. The results showed that in rainy season, the average actual water used from three lysimeter tanks were slightly changed. The maximum soil moisture content was 0.392 cm³.cm^-3 and minimum was 0.231 cm³.cm^-3. On the other hand, the average soil moisture content from three lysimeter tanks that predicted by the model was highly varied. The maximum soil moisture content was 0.558 cm³.cm^-3   while the minimum was 0.063 cm³.cm^-3 .  The results obtained from two methods were rather different, and when analysis was made to find out the correlation, the coefficient was only 0.848. During dry season, the average actual water used from three lysimeter tanks were slightly changed. The maximum soil moisture content was found at 0.371 cm³.cm^-3  and minimum was 0.275 cm³.cm^-3 . However, the model showed that the range of changes in soil moisture content was narrower than the rainy season. The maximum soil moisture content was 0.41 cm³.cm^-3 while the minimum was 0.198 cm³.cm^-3 when the correlation coefficient of two methods was made, it was found at 0.978.