Drainage Requirements for Alfalfa Grown on Sandy Soil

ALFALFA hay yields were evaluated as functions of watertable depth and irrigation level for a sandy soil in field plots and field lysimeters in southeastern North Dakota. Data from two cropping years, after an initial crop establishment year, for each experiment are included in this report. Yields were normalized on an annual basis, a 4-plot-year basis, and then the data from both experiments were combined to provide information for a wider range of watertable depths and irrigation levels. Results showed that the optimum watertable depth for maximum yields was 1.5 m and that irrigation was unnecessary when the watertable was maintained at this optimum depth. For alfalfa production significant energy and cost savings, estimated at $57/ha annually, can result by omitting irrigation which can be done when a shallow 1.5 m watertable is present.