The Effect of Preplant Monoammonium Phosphate Fertilizer and Compost on the Growth and Yield of 'Macoun' Apple Trees

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  • 1 Department of Plant, Soil and Environmental Sciences, University of Maine, PO Box 179, Monmouth, ME 04259
  • 2 Pennsylvania State Fruit Research and Extension Center, 290 University Drive, Biglerville, PA 17307

'Macoun'/B.9 apple (Malus ×domestica Borkh.) trees were planted in May 1998 in ± compost or ± monoammonium phosphate (MAP) for a total of four preplant treatments: 1) 90 g phosphorus (P) per tree, 2) 128 kg compost per tree, 3) 90 g P and 128 kg compost per tree, and 4) and an untreated control. MAP did not increase tree growth or yield in any year of the study. Compost increased canopy width into the sixth year after planting, and increased tree height and trunk cross-sectional area (TCA) into the seventh year. Annual yield was increased by compost in the fifth and seventh years, but not fourth or sixth year after planting. Compost increased cumulative yield in the sixth and seventh years.

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