Mechanical Impedance and corn Seedling Root Growth

Using needle penetration and bulk density as measures of mechanical impedance, the effects of mechanical impedance on corn seedling root growth were studied in the laboratory. The corn seedlings were grown in artificially compacted samples of a Colo clay where the moisture was at a tension of 10 cm. in some samples and 100 cm. in others. The rate of corn seedling root elongation decreased linearly as bulk ensity of Colo clay increased from 0.94 g. per cc. to 1.30 g. per cc., or as needle penetration into the Colo clay decreased. In ohter laboratory experiments, the depth of corn seedling root penetration into sand contained in glass tubes of differing diameters was found to be linearly related to the depth of penetrometer penetration.