CHANGES IN SOIL DENSITY, MOISTURE, STRENGTH, AND RESIDUE COVER INDUCED BY TILLAGE AND TIME.

摘要

The development of new conservation tillage implements and the need for better devices and procedures for evaluating these implements were the primary reasons for undertaking this research.; The effects of tillage and time on soil density, moisture, penetration resistance, and percent residue cover were evaluated under field conditions. Evidence was found that the chisel plow, the no-till, and the newly introduced paraplow tillage systems are potential soil and water conservation methods.; Adequate precipitation in the experimental site masked the effect of tillage on soil moisture.; Paraplowing resulted in lower bulk density and cone index values than did chisel plowing and the changes caused by the paraplow were longer lasting. Disking of the chisel plowed plots in the spring increased the bulk density and the cone index to the equivalent of the no-tilled soil. Soil moisture and bulk density were found to be insufficient to predict soil strength.; The no-till resulted in a lower percentage reduction of residue throughout the year than did the paraplow which managed the residue better than did the chisel plow system.; High density, penetration resistance, and residue cover apparently combined to reduce the corn yield of the no-till system when compared with the equal yields produced by the paraplow and the chisel plow systems.; A microcomputer-based penetrometer was constructed and used to record, store, and display penetration force and depth values. When compared with a hand-held penetrometer, the new penetrometer was found to be fast and precise.