NEGATIVE EFFECTS OF EXCESSIVE NITROGEN AND POTASSIUM FERTILIZATION IN A REPLANTED APPLE ORCHARD

Different N and K fertilizer doses were applied for 16 years in an old apple orchard and then continued in a replanted orchard.
No significant effect of fertilization upon growth or bearing of old trees was notet.
However, in a replanted orchard a reduced growth, lower yields and higher mortality of trees has been recorded at 140 kg and even more at 240 kg of N per ha.
This was attributed to a toxic action of Al and Mn which were present in high concentrations in a root zone when soil acidity was drastically lowered by high N doses in the form of NH₄NO₃. Potassium fertilization reduced leaf Mg content, increased Mg deficiency symptoms, reduced growth and yields, and increased mortality of replanted trees.
It has been concluded that a part of failures of replanted orchards may be caused by excessive fertilization prior and after replantation.
Appropriate applications of lime may partially reduce negative effects of excessive N and/or K fertilization.
The presented data suggest a better growth and bearing of trees when replanted along former tree rows (in herbicide strips) compared with those planted in former grassed alleyways.

Workshop on Replant Problems with Fruit Trees

A. Sadowski, K. Scibisz, K. Tomala, T. Kozanecka, M. Kepka

https://doi.org/10.17660/ActaHortic.1988.233.14