Soil, Tree, and Fruit Responses to Lime and to Type and Timing of Nitrogenous Fertilizer Applications under ‘Sturdeespur Delicious’ Apple trees1

Incorporating high Ca lime with the soil in the planting hole for trees of ‘Sturdeespur Delicious’ apple ( Malus domestica Borkh.) on Malling-Merton 106 rootstock increased leaf Ca for the first 2 years. Annual soil applications of NH 4 NO 3 for 8 years, in comparison to applications of KNO 3 or Ca (NO 3 ) 2 , increased acidity of soil to depths of 50 to 61 cm. Soil Ca levels were reduced by NH 4 NO 3 but were not increased by Ca (NO 3 ) 2 . The trees were fertilized either 1 month prior to bloom or at bloom. Time of application or N source had no appreciable influence on tree growth, leaf nutrition, yield, fruit Ca levels, bitter pit and cork spot, or internal breakdown after storage.