Abstract
A three-year study investigated the use of saline (EC < 6 dS m (-1)) drainage water for irrigation of salt-tolerant alfalfa in the presence of shallow saline groundwater. The irrigation treatments included: (1) irrigating twice between cuttings with nonsaline water, (2) irrigating twice with moderately saline water between cuttings, and (3) once between cuttings with moderately saline water. Yield data demonstrated an approximately 30% reduction in total yield over 3 years as a result of using the saline water for irrigation compared to irrigating with the nonsaline water. The overall alfalfa quality improved when irrigated with saline water compared to the non-saline water. However, both boron and chloride progressively accumulated in alfalfa plant tissue during each growing season when irrigated with saline water. The plant tissue boron and chloride values returned to previously low levels by the start of the next growing season due to the influence of winter rainfall and irrigating with low-salinity water at the break of dormancy. There was measurable accumulation of salt in the soil profile and in the shallow groundwater as a result of using saline drainage water for irrigation. A gradual decrease in depth to the shallow groundwater was observed as result of the lack of drainage capability. Electromagnetic induction proved adequate for characterizing root zone salinity with time. Published in 2010 by John Wiley & Sons, Ltd.