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Interpretive Summaries:
2000 - Reassessment of Potassium Critical Values, and the Predictive Value of Early Leaf Potassium in Almonds
1999 - Reassessment of Leaf Potassium Critical Values in Almonds
1998 - Reassessment of Leaf Potassium Critical Values in Almond
Reassessment of Potassium Critical Values, and the Predictive Value of Early Leaf Potassium in Almonds, 2000
Almond yields have increased substantially since the University of California (UC) guidelines for leaf K were first published in the early 1960s. Increasing numbers of growers and analytical laboratories are concerned that current UC guidelines for leaf K are inadequate. This project was conducted from 1998 through 2000 to evaluate and update these guidelines and to measure yield and quality responses to K fertilization.
A vigorous almond orchard with low leaf K levels was chosen as the study site. Baseline yields for individual trees were determined in the initial year, and K2SO4 was applied annually at 0, 120, 240, and 360 lb K2O/A to establish a broad range of tree K nutrition. Survival of fruiting spurs from 1999 into 2000 was 23 percent greater, and spring flowering of the surviving spurs was 20 percent greater under high K availability compared to low K availability. Nut yield was increased by 400 meat lb/A. It was concluded that July leaf samples are generally predictive of next season’s productivity, but not the current season. Leaf K concentration of 1.4 percent is adequate for maximum yield.
Better understanding of the K nutritional requirements and diagnostic criteria of almond, the leading nut crop grown in California, can rapidly lead to a substantial increase in K fertilizer demand. CA-20F
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