Soil Available Water Capacity Research Articles

COMPARISON OF THE CERAMIC PLATE AND THE PRESSURE MEMBRANE TO DETERMINE THE 15 BAR WATER CONTENT OF SOILS

SummaryVolumetric water contents of 17 mineral and 3 peat soils were measured at 15 bar pressure using the ceramic plate and the pressure membrane apparatus. There was no overall significant difference between the results from the two types of apparatus and both ranked the soils in essentially the same order. Although soils of high clay or organic matter content retained up to 13.5% more water on the ceramic plate than on the pressure membrane, available water capacity (AWC) of a clay soil would be decreased by only 1–2%, and that of a peat soil by 3–4%. Due to its greater reliability, the ceramic plate is an acceptable alternative to the pressure membrane when used to determine the 15 bar water content.

The relation between bulk density, available water capacity and air capacity of soils: J.R. Archer and P.D. SmithJ. Soil Sci.23 (4), 475–480 (1972)

The effect of bulk density on moisure content at 50 mb tension in four soils of different textures was studied. The volumetric water content increased linearly with bulk density over a wide range of densities. Depending on texture, a maximum bulk density was reached above which continued compaction decreased the water content. This is shown to be the point at which air capacity of the soil at this tension approaches zero. Accepting that the gravimetric wilting point depends mainly on texture, the available water capacity varies in a manner similar to the 50 mb water content.