UC Cooperative Extension advisors help spinach growers finesse fertilizer applications

UC Cooperative Extension advisors are studying the critical balance between fertilizer application and absorption in Salinas Valley spinach crops to help farmers meet new water regulations, reported Dennis Taylor in the Salinas Californian.

Richard Smith and Michael Cahn, UCCE advisors for Monterey and other Central Coast counties, have been conducting field trials for several years to determine volume data on fertilizer application. Once growers know exactly how much nitrogen their crop is absorbing, they can more precisely apply an appropriate amount.

Smith explained that baby spinach will absorb roughly 80 percent of the nitrogen it is going to take up in the final two weeks before harvest, making timing critical, Taylor reported. Spinach harvested a few days later, called "teen spinach" uses about 100 pounds of nitrogen per acre; larger-leafed spinach can used up to 120 pounds.

“No (previous) studies had evaluated high-density planting of clipped or bunched spinach grown on 80-inch beds,” said UCCE research assistant Aaron Heinrich. “Our study was specifically designed to provide data on the nitrogen uptake characteristics of spinach and to evaluate ways to improve nitrogen fertilizer management.”

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