Principles of Water Capture, Evaporation, and Soil Water Retention.

Successful dryland crop production in semiarid environments is dependent upon efficient storage of precipitation and use of stored soil water supplies. The objectives of this presentation are to: 1. Summarize information regarding the effects of time of year; environmental parameters; residue orientation, cover, and mass; soil type and texture; and tillage on precipitation storage efficiency, and 2. Summarize information regarding the factors influencing precipitation use efficiency. Data are presented from two distinctly different rainfall regimes: the central Great Plains with a predominantly summer precipitation pattern and the inland Pacific Northwest with a predominantly winter precipitation pattern.