A field experiment was established in 1992 with `Empire' apple trees on either M.7 or M.9 rootstock. Preplant fertilization with NPKB plus lime compared to the lime only control did not increase tree growth during the first 4 years, but did increase cumulative yield (10%) and average fruit size (7%). The addition of annual applications of ground-applied NKB after planting increased total shoot growth 17%, as well as yield (26%) and fruit size (14%) compared to the lime only control. Trickle irrigation significantly increased trunk cross-sectional area (17%), shoot growth (16%), yield (18%), fruit size (5%), and yield efficiency (7%). The interaction of ground fertilization and trickle irrigation showed that trickle irrigation increased the benefits of ground applied fertilizers. Without trickle irrigation, ground-applied fertilizers increased shoot growth only 6% and yield 14% compared to the unfertilized controls, but, with the addition of trickle irrigation, the ground-applied fertilizers increased shoot growth 21% and yield 21% over the irrigated but unfertilized control. Ground fertilization increased yield efficiency and fruit size by the percentage by whether or not trickle irrigation was present. Fertigation gave similar results as the trickle plus ground fertilizer treatment on tree growth, yield, fruit size, and yield efficiency. Our results indicate that trickle irrigation in the eastern United States can improve tree growth, yield, and fruit size in the first few years after planting. The addition of ground-applied fertilizer or fertigation can improve tree performance even more. However, in the humid New York climate, there does not appear to be a significant benefit from injecting the fertilizer into the trickle water compared to applying the fertilizer on the ground.
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