Lower limit of available water for three plant species grown on a medium-textured soil in southwestern Saskatchewan

Numerous researchers estimate and report laboratory-determined lower limit of available water contents using −1.5 MPa water potentials. For medium-textured soils, laboratory-measured lower limits should be determined at potentials of at least −4 MPa, and possibly −10 MPa, when using pressure membrane procedures. However, because the lower limit of available water is dependent upon environmental, plant and soil factors, we agree with Ratliff et al. (1983) that field-measured lower limits are preferable to laboratory-measured lower limits. Field-measured lower limits of available water did not vary markedly between spring wheat, alfalfa and grass.