Strawberry Performance During Establishment with Reduced Irrigation

Strawberry, a major crop grown in Ventura County, CA, has an annual value of 515 million.  Each September, 1.2 m-wide raised beds are constructed with two drip irrigation lines installed at 5-8 cm depth. The beds are covered with polyethylene mulch, fumigated via drip and in October bare-root transplants are planted in holes punched in four rows 30 cm apart from the two drip lines.  For the first 5-8 weeks after planting, overhead sprinkler irrigation in daily amounts ranging from 50-60 mm is used instead of drip to rapidly hydrate plants, aid adventitious root development, and leach salts from the root zone.  In a large-scale field study conducted at Camarillo, CA (in 2010), we evaluated strawberry establishment with reduced sprinkler irrigation and drip-only irrigation with two different placements of four drip lines. Water use, electrical conductivity (EC) of soil in planting holes at 5 cm depth and strawberry performance were measured during the 8-week plant establishment period. Water use was reduced 49% in drip-only treatments compared to reduced sprinkler and there was no runoff in drip-only systems. Soil pore EC in drip-only plots with four buried lines was 25% to 58% greater compared with either surface drip system with four lines or partial sprinkler. Strawberry mortality was similar in all irrigation systems and less than 2%, a level acceptable for commercial production.  Strawberry plants were also 13% smaller with partial sprinkler irrigation than in drip-only systems. Dry biomass of new leaves was similar among treatments, but new root biomass in reduced sprinkler and surface drip treatment was 35% greater than with buried drip irrigation, likely due to greater salinity in the root zone in buried drip system. Early fruit production was similar among treatments. These results suggest that reduced irrigation and precise water placement are adequate for strawberry establishment, provide substantial savings of water, and minimize runoff, a major benefit to the environment