Large Bed Vegetable Cropping Systems Enhance Productivity and Water Conservation

Recently, a number of lettuce (Lactuca sativa L) producers in the desert southwest have shown interest in using a wide (2 m) bed system relative to the conventional practice of growing the crop on a more narrow (1 m) bed system. A field study was conducted during the 2010-2012 winter growing season to evaluate bed size and three irrigation methods for romaine and iceberg lettuce. The trial included solid-set sprinkler and subsurface drip plots, each managed by Et replacement, and furrow irrigation applied when available soil water was depleted by 40%.  When compared to drip, 60% and 41% more water was applied to lettuce grown with either sprinklers or furrow, respectively.  Naked romaine or romaine hearts grew equally well in either narrow or wide bed systems. However, sprinkler irrigated romaine produced slightly lighter heads (3%) and hearts (10%) relative to drip irrigated romaine.  Iceberg lettuce, harvested as either a wrapped or cored head (bulk for salad processing) weighed 17% greater when grown in narrow beds relative to wide beds. Irrigation method was equally striking with drip irrigated iceberg outperforming both furrow and sprinkler by as much as 16%.  In fact, sprinkler irrigated iceberg produced heads which were either 7% (wrapped) or 15% (cored) lighter when compared to iceberg grown under drip regardless of bed configuration. The results from this study demonstrate a great potential for water conservation and field productivity by producing romaine lettuce on large beds.