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Strawberries, Soils and Water

EVALUATION OF CONTROLLED RELEASE FERTILIZERS AND FERTIGATION IN STRAWBERRIES - 1998

A fertilizer trial was established in a commercial strawberry field southeast of Santa Maria. Three controlled release fertilizers were applied on October 28, 1997, at the rates of 80 and 160 pounds of nitrogen per acre compared to a commercial fertilizer at 160 pounds of nitrogen per acre and a control with no preplant fertilizer. All 8 treatments received the same fertigation program as the grower's commercial field. The grower applied a total of 185 pounds of nitrogen per acre throughout the production season.

The variety Camarosa was planted on November 1, 1997, with plants from a McArthur nursery dug on October 27, 1997. Each strawberry bed had 4 rows of plants spaced 10" apart. The plants were spaced 14" apart within each row.

The trial received the same irrigation, pest control, and picking schedule as the commercial field. The soil type is a sorrento sandy loam.

The strawberries were harvested as fresh fruit all season because the grower sold the fruit in a fruit stand. The spring rains delayed the first harvest until March 20, 1998. The last harvest was August 3, 1998. Heavy rain periods in March, April and early May reduced yield and delayed harvest schedules. During April, May, June and July, the trial was harvested on a 3 or 4-day schedule.

The 1997-98 Santa Maria rainfall from July 1-June 30 was 32.6", which was over 2 1/2 times the normal rainfall of 12.5". The strawberries were harvested by the grower’s commercial strawberry pickers. The fresh yields are based on the grower’s high standard for fruit quality. The yield data is the average of the four replications from 64" wide by 30' long plots.

RESULTS
The strawberry yields are shown in Table 1. The trial showed a yield response to preplant fertilizers. All of the preplant fertilizer treatments produced significantly higher strawberry yields than the control treatment that received only fertigation. Similar trials, conducted the two previous years, showed the preplant applications of 160 pounds of nitrogen per acre produced higher yields than the 80 pounds of nitrogen.