Measurement of capillary rise under field conditions and related soil properties
Capillary rise, measured at two sites in one orchard over three experimental periods supplied from 45 to 79% of the water used by herbaceous cultures during these periods. The water table was unusually deep in 1978 and, because of the consequent low rates of rise, no measurement of capillary rise was possible in 1978
a reminder that capillary rise is a reliable source of water for plant growth only if water table depth is relatively stable. Hydraulic properties of core samples from the capillary rise sites fell well within the range of samples from eight other sites that represented the range of texture of orchard soils in the region (sand, loamy sand, sandy loam and loam). Thus, given similar water table depths, rise in many soils of the region, would probably equal or exceed the rise that was observed in the experimental orchard. Observed rise agreed closely (within a factor of 2) with rise calculated from core properties, water table depth and soil moisture tension on one site but cores from the second site were more variable and agreement was less good. Correlations between hydraulic properties and other soil properties suggest that capillary rise parameters were adversely affected by the high bulk density of these subsoils. Increase in bulk density was associated with a need for shallower water table (for a given flux) and a greater sensitivity of flux to change in water table depth. Percent sand and fineness of sand were the dominant textural controls of rise parameters. Capillary rise from water tables within subsoils of unusually high bulk density (approaching 2 g/cm3) is not likely to supply appreciable water for plant growth under field conditions.