Enige aspecten van de waterbeheersing in landbouwgronden

First a review was given of the water requirement and the relation between water use and crop yield. Next the energy status and the mobility of water in the soil were discussed. Based on physical theories a method was developed of calculating the amount of available moisture in the soil with different watertables, physical properties of the soil, transpiration intensity of the crops and root density.

Aeration of the soil was similarly treated. Published data on carbon dioxide production, root density and microbiological activity in the soil were used to develop a mathematical model to derive oxygen and carbon dioxide contents in the root zone. The model was based on steady-state diffusion of gases through the soil.

The models developed were used to derive the watertable required under natural conditions and with subsurface and sprinkler irrigation.

Further a series of experiments in drained plots were described. Apparatus for recording drain discharge and depths of watertable were discussed. Results were analysed to find what factors influenced actual watertable and what criteria should be applied in the design of drainage systems.