Ag. 15.30 In the description of this experiment, the researchers failed to note that the experiment in fact had been conducted at four different orange groves, which were located in different states. Grove 1 had a soil pH of 4.0, grove 2 had a soil pH of 5.0, grove 3 had a soil pH of 6.0, and grove 4 had a soil pH of 7.0. At each of the groves, three trees were randomly assigned to one of the calcium levels: 100, 200, or 300 pounds per acre. The data are given here.