Nutrient Management Research Database

http://ucanr.edu/sites/Nutrient_Management_Solutions/files/212708.pdf

An understanding of the seasonal uptake and partitioning of mineral nutrients of grapevines is essential in order to time fertilizer applications. Over the last three decades, several important studies were conducted to determine seasonal nutrition demands of field-grown grapevines and to quantify the partitioning of mineral nutrients (Christensen 1980, Conradie, 1981, Peacock, 1986, Peacock et al, 1989; 1991, Williams, 1987, Williams and Biscay, 1987). This paper aims to summarize what has been learned over the last few decades and highlight advances in grapevine mineral nutrition.

This paper summarizes research on mineral nutrition in table grapes, presenting information on nitrogen (N), potassium (K), magnesium (Mg), and zinc (Zn), as well as cultivar and rootstock effects on mineral nutrition.  

This review of table grape mineral nutrition research, recent as of 2009, focuses on nitrogen, potassium, magnesium and zinc uptake.  As with all crops, the timing of N applications (and other nutrients) should occur when demand and plant uptake is the highest.  For table grapes, N demand is highest during the spring period of rapid vegetative growth, although as much of 40% of this need is satisfied by remobilization of N from permanent woody structures.  N uptake is highest between bloom and veraison, and applications should be applied late in spring. Postharvest N applications may also be efficient, depending on location and variety.   The review gives estimated N requirement based on average yields as well as factors for determining the correct amount of N to apply, including N in irrigation water, crop residues/cover crops, and soil organic matter.

The author states that the need for potassium (K) is most critical during berry development and ripening, and because of this K should be applied in the early spring, ideally through drip irrigation in small amounts over 10 to 15 weeks.

The review suggests that Magnesium application, if needed, is best applied through drip irrigation or foliar sprays anytime during the spring.  In addition, zinc can also be applied through foliar sprays before bloom.  Finally, considerations of cultivar and rootstock selection are briefly discussed.