Effect of covercrops on the soil solution at different depths under orchard conditions

Abstract does not appear. First page follows.

Two earlier papers^{(4), (5)} have presented progress reports concerning changes in concentration of the more important ions in the soil solution under a variety of covercrop treatments and with different species of trees. These results were obtained from the orchard of the Pomology Division of the California Agricultural Experiment Station at Davis. The crop history has been given⁽⁴⁾ in a former paper and is not essential for consideration of the data given here. The plot treatments were alfalfa sod (Medicago sativa); a summer covercrop of mat bean (Phaseolus aconitifolius), which was superseded by Dolichos lablab in the seasons 1931 and 1932; and winter covercrops of rye (Secale cereale) and of Melilotus indica. These were all compared with three clean-cultivated checks. The treatments were duplicated. They ran in strips across the species plantings of pears, prunes, apples, Japanese plums, cherries, apricots, and peaches as shown in figure 1. The method used in obtaining the soil solution has been described elsewhere⁽³⁾, and is essentially a displacement rather than an extraction with an excess of water.