Comparison of Prediction and Actual Measurement about Dynamic Distribution of Soil Moisture Tension

Experimental studies on sub-irrigation method (V)

Abstract

The distribution of soil moisture tension under the conditions applied to the sub-irrigation method by use of the finite element method in case of the bare soil condition and crop cultivation. In the above case, the movement of soil moisture was dealt with in the non-steady state, and investigations were attempted to reappear and predict the distribution of soil moisture tension occuring around the ceramic watering pipe.
The results are as follows.
First, the distribution of soil moisture tension with regard to the difference in the negative pressure head, the difference in soil texture, and the existence of root zone were understood to be able to reappear due to the use of the finite element method in the non-steady state.
Second, to predict the distribution of soil moisture tension under the bare condition, the qualitative tendencies of the results obtained from the calculations were understood to be same as the actual measurements.
Third, to predict the distribution of soil moisture tension under the crop cultivation condition, the qualitative tendencies of the results obtained from the calculations were different from the actual measurements to a slight extent. These differences were guessed to be influenced by the strength of water absorption of the roots and the initial conditions setted.