Criteria for pot capacity determination

The field capacity, or its equivalent for soils in pots, the pot capacity, is an important parameter for irrigation management. We aimed to determine both water content and water. loss as a function of time in pots filled with material of a clayey and a medium-textured soil. From these data the pot capacity water content was estimated using different criteria. It was concluded that the final water content extrapolated from the observed q-t curve is a good estimator of the pot capacity, especially in situations of low water loss tolerance. An estimation of the pot capacity according to traditional pressure heads or drainage times is not recommended, since the obtained values are overestimated, compared to the values obtained by the q-t curve and correspond to high reduction rates of the water content.