Experimental Plan
The site selected for the orchard is a gentle slope varying from five to 15 percent and providing good air drainage. The soil is a Riverdale (tentative series) sandy loam that had been in orchard grass sod for 10 years before the experiment was begun. Much of the land on the Plant Industry Station farm is now known to be low in available magnesium and potassium. Tree crops, including peaches, pears, and apples, have shown deficiencies of one or both of these elements. The trees were planted 20 feet apart on the contour in pairs, one of each variety in a plot, with six plots in a row. The 36 two-tree plots were in six rows. Thus, the experiment was arranged in a 6 by 6 Latin square and six fertilizer treatments were used. After planting, the trees received frequent cultivation and a uniform application of one pound of 10-6-4 fertilizer. The following spring differential fertilizer treatments were applied: Nitrogen, phosphorus, potassium, complete, nitrogen and potassium, and check. The amounts applied per tree in fractions of a pound were elemental nitrogen 0.2, phosphoric acid, 0.4, and potash 0.2. In the spring of 1950, the amounts applied per tree were doubled; and these same amounts were applied in the spring of 1951. Nitrogen was applied in the form of nitrate of soda, phosphorus as 20 percent superphosphate, and potassium as 50 percent muriate of potash. Strips about six to eight feet wide on each side of the tree rows have been cultivated frequently, but strips of orchard grass sod have been left in the tree row middles to prevent soil erosion. The trees have been sprayed with DDT or parathion or both to control Japanese beetles and mites.