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Nutrient Management Research Database
General Information
Research Title
Link to File
Research Specifications
Authors
Summary/Abstract from Original Source
Research Highlights
Design and Methods
This study looked at how apple trees use P, following patterns of tree P uptake as well as how P behaves once it is in the tree.
Over the course of a growing season, total tree biomass was measured along with P accumulation in a 9 year old 'Fuji' orchard
Measurements were taken at five dates:
- Early growth (March 26th)
- Young fruit stage (April 30th)
- Fruit expansion (July 30th)
- Fruit maturity (September 21)
- Tree dormancy (January 15)
Results
Plant biomass sharply increased between the early growth period until harvest. After harvest tree growth slowed considerably.
Most P uptake occurred in August and July. Before this time trees used P that had been stored from the dormant period.
P accumulation totaled 25 lbs P/ac with a crop of 1000 bushels/ac. A total of 64% of this P was taken up between July 30th and September 21st. Between September 21st and January 15th, the remaining 36% of P was taken up by tree roots.
The authors recommend application rates of about 100 lbs P/ac, with 60 lbs applied to the base of the tree after harvest and 40 lbs applied prior to fruit expansion.
Other Considerations
P fertilizer applicaton rates should be adjusted according to soil test results.