Wasserhaushalt und Entwässerung von Weideböden

Water balance and drainage problems of pasture soils

Birmensdorf

1963

S. 247-269

16 Abb.

Bandaufführung

1265

157531

The availability of soil water to plants and the water content of the soil are a function of water tension. The water movement is a function of the conductivity and of the hydraulic gradient between two points in question of a soil. In humid regions the soil moisture tension can apporximately be mearsured by the hydrostatic pressure. The relation between water content and tension of soil moisture can be shown by the water-sorption-curve. Drainage problems occur in imperfectly drained soils. According to the degree of impermeability, a water tabel can wet the rooting zone to a different depth, for different time - lenght and after variable time - intervals. It is the aim of a good drainage system to keep a water table the rooting zone or at least to minimize its injurious influence to the growth of afforestations. The drawdown of the water table in slope-soils is determinded by an electrical resistance network (Luthin, 1953). It is planned to work out drainage-solutions for representativ pasture-soils as a function of +) hydraulic conductivity +) depth of the impermeable layer +) interface of layers with different hydraulic conductivity +) slope +) drain spacing. These soils have a characteristic morphologiy in situ. An unknown soil with similar drainage possibilities will also have an analogous morphology. Comparing the morphology of an unknown soil in situ with the morphology of the representative soils, it should also be possible to interpret the drainage possibilities of the soil in question. this will be a rough first approximation for aolving a drainage problem. If more information are needed, the same investigastion are necessary for each single case as they were done for the representative soils.