An economical, automated method was developed for measuring soil water evaporation during first‐stage drying simultaneously at several locations in a field to evaluate the effectiveness of mulches and crop canopies in reducing soil water evaporation. The method also provides a reasonable procedure for separating soil water evaporation during first‐stage drying from transpiration, when the total evapotranspiration rate is accurately measured.Water flow through a thin evaporation plate with a known surface area is measured and used as a direct indicator of the evaporation rate. Flow rates can be recorded manually or automatically.Field tests of evaporation indicated that the resolution of the system was equal to that of a precision weighing lysimeter and that the system gave reasonable accuracy on an hourly basis. Mulch rates of 1,000, 4,000, and 10,000 kg ha‐1 reduced daily soil water evaporation measured with this method by 26, 59, and 78% of the bare soil evaporation. Cumulative daily soil water evaporation was reduced by 57 and 71% under plant canopies with 100‐ and 50‐cm row spacings and similar leaf area indices (3.0 and 2.7, respectively).