Fig. 1.

Daily precipitation during the 2003 to 2008 fallow periods at Lind, WA. Also shown is the timing of 180-cm deep volumetric water profile measurements obtained each year at the beginning of the fallow period, in the spring of the fallow period, and at the end of the fallow period. Total precipitation (mm) between those points is noted. The date when incremental seed-zone water samples were obtained is indicated by a triangle. Horizontal bars indicate individual fallow periods and are labeled with the year the fallow period ends.

 


Fig. 2.

Seed-zone water content profiles measured in late August from 2003 to 2008. Samples were taken in 2-cm increments from 0- to 26-cm depth (22 cm in 2003) and are plotted on a dry soil mass per area basis. The horizontal guideline marks 200 kg m−2 used for equivalent-mass treatment comparisons. NTF = no-till fallow.

 


Fig. 3.

Average seed-zone water content over the 6-yr period (each point is the mean of 6 yr and four replications). Treatments are significantly different at 200 kg m−2 (p > F = 0.0016). All non-adjacent means at 200 kg m−2 are significantly different at p > |t| = 0.04. The year by treatment interaction was not significant.

 


Fig. 4.

Volumetric water content at the end of the fallow period to a depth of 180 cm from 2003 to 2008. Each data point is the mean of four replications. NTF = no-till fallow.