ISHS Acta Horticulturae 347: II International Symposium on Integrated Fruit Production
THE FERTILIZER REQUIREMENT OF YOUNG APPLE TREES AS AFFECTED BY RESTRICTING THE FERTILIZER PLACEMENT TO THE HERBICIDE STRIP |
| Authors: | J. Ystaas, O. Frøynes |
| Abstract:
In a 'Quinte' apple orchard with soil management systems of either complete grass cover or mown grass alleyways combined with herbicide strips, 1.0 m and 1.75 m wide, the effect of fertilizer placement was studied in a 10-year experiment starting in 1982. Differential rates of N fertilizer (nil, 40 or 80 kg ha-1) combined with three rates of K fertilizer (nil, 60 or 120 kg ha-1) were applied to each soil management regime every spring. The fertilizers applied were broadcast in the complete grass cover system but restricted to the herbicide strips in the system of herbicide-treated tree rows. Tree size and yield of the trees growing in the herbicide strips were significantly greater than trees growing in complete grass. Fruit size and fruit quality were not affected by different soil management and fertilizer applications. Mineralization of N from soil organic matter of a sandy soil (7% organic matter content) satisfied the needs for nitrogen of young apple trees in full production, when grown in herbicide strips without competition from weeds and grass. Leaf N concentration was reduced by 0.3% when trees were grown in complete grass cover. Although the level of soil exchangeable K was low, the trees did not respond to potassium application. Apparently non-exchangeable K was released at a rate sufficient to meet the demand. Restricting the fertilizer placement to the herbicide strip reduced substantially the amount of fertilizers necessary to maintain an optimal level of nutrients in the tree. | |
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