Smith, E. M. and K. W. Reisch. 1974. Fertilizing trees in the landscape — Progress report. Research Summary 79, OARCD, Wooster, Ohio.
A fertilizer study was conducted in a relatively poorly drained, Blount and Morley silt and Pewamo silty clay-loam area at the USDA Shade Tree and Ornamental Plants Laboratory in Delaware, Ohio. The trees were treated on May 5, 1971. All trees receiving fertilizer treatments also received 6 lb. of actual phosphorus and potassium per 1000 sq. ft. at the time of nitrogen application. The drill hole treatment consisted of 20 holes per tree, 12 inches deep, in two concentric rings covering an area of 100 sq. ft. under each tree. The trees were pruned as needed and the area between the trees was maintained in sod and mowed periodically. On Sept. 18,1973, afterthree growing seasons, the caliper of the trees was measured 1 foot from the ground. The results of caliper measurements are shown in Table 1.
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