Abstract
The clogging of filter and emitter in microirrigation system are serious problems for keeping water constant supply during cropping season. The effects of algae clogging were discussed by using various kinds of filters and emitters of the microirrigation system under conditions of polluted and unpolluted irrigation water. There are high relationships between concentration of chlorophyl a in algae and turbidity or suspended solid. Since size of algae contained was smaller than the opening diameter of filter element when polluted water was used, the emitter clogging was slightly improved by the volume type filter rather than the areas type of filter.
In the case of unpolluted irrigation water where natural spring water was used, longer size algae extremely increased during irrigation season. The area type filter was not effective to remove algae but suspended solids contained in irrigation water. The volume type filter was effective to decrease the emitter algae clogging when algae were filtrated in the short irrigation periods of two to three months. Under longer irrigation periods, however, the algae were absorbed with filter element too tightly to clean up by the system of automatic back washing of filter.
