ISHS Acta Horticulturae 367: VI International Symposium on Pear Growing
NITROGEN REQUIREMENTS AND NITROGEN-UPTAKE EFFICIENCY FOR COMICE PEARS |
| Authors: | T.L. Righetti, H. Khemira, D. Sugar, E.E. Sanchez |
| Abstract:
‘Comice’ pear trees require little exogenous nitrogen. We estimate that only 15–25% of the N applied to an orchard is taken up by the trees. This compares to the approximately 50% recovery often reported for field crops. Rapidly growing young pear trees accumulated less than 50 kg N/ha in one year. Three to four times the total amount of N uptake are routinely applied to commercial orchards. If one assumes that at least half of a tree's N needs could be met by the mineralization of soil organic matter, only 25 kg N/ha exogenous N is required. Approximately 50% of the annual N uptake could be accounted for in the harvested fruit. A major factor affecting nitrogen uptake efficiency is the variability in tree size within an orchard. Even at modest doses (50 kg N/ha) small trees were unable to effectively utilize the added N. Although the largest trees approached 50% recovery of the added N, smaller trees were much less efficient. | |
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