Soil water release curves. Data points with large symbols were measured using a WP4 dewpoint meter. Data points with small symbols were measured using a Tru Psi thermocouple psychrometer. Coefficients are given for the curve: ln (water potential) = m × (gravimetric water fraction) + b.

Fig. 2.

Mean number of days to attain 75% germination for the three soil types, each at four different water potentials. Note that not all seed lots attained 75% germination at the four lowest water potentials (see Table 2).