The fate of15N labeled nitrogen applied to mature citrus trees |
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Authors: | Sala Feigenbaum H Bielorai Y Erner S Dasberg |
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Institution: | (1) Institute of Soils and Water, Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel;(2) Division of Citriculture, Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel |
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Abstract: | Summary The efficiency and balance of nitrogen from one year's application was studied in a long-term fertigation experiment. Enriched
nitrogen fertilizer, K15NO3, was applied to a 22-year-old Shamouti orange tree with a history of high N applications (N3) and to an N-starved tree (N1). The distribution of N in the different parts of the trees and in the soil was determined after the experimental trees were
excavated.
Similar total recovery of the labeled fertilizer N was found in the trees and soil in both treatments (N1−61.7% N3−56%). However, the distribution between tree and soil was different. The amount of recovered residual fertilizer in the soil
was much larger in the N3 treatment than in N1. The highest percentage of fertilizer N was found in the new organs,i.e. fruits, twigs and leaves. The roots and branches took up only 6–14% from the labeled fertilizer.
Only 20.9% of the leaf N and 23.4% of the fruit N in the N3 tree originated in the labeled fertilizer, indicating translocation of N from older parts of the tree to new growth.
Evidence was found of storage of N in the wooded branches, while the roots contained a surprisingly small part of labeled
fertilizer.
Contribution 1599E. |
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Keywords: | Citrus sinensis Dry matter distribution Fertigation Hamra soil Leaf area index Mediterranean climate Nitrogen distribution Nitrogen recovery Nitrogen uptake Oranges Shamouti |
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