Physical Properties of a Typic Haplaquoll Under Conventional and No-Tillage1
- J. L. B. Culley,
- W. E. Larson and
- G. W. Randall2
Conservation tillage, particularly no-till (NT), for corn (Zea mays L.) production on poorly drained soils in the U.S. Corn Belt often produces lower yields. Cone index (CI), bulk density (ρb), shrinkage, hydraulic conductivity (Ks), and water release charcteristics were all measured in a Typic Haplaquoll under NT and conventional tillage (CN) to characterize soil physical factors possibly related to the lower yields. Measurements in the interrows indicated that wheel traffic, associated only with crop establishment (planting and herbicide spraying), eliminated the benefits of lower CI and greater Ks associated with primary and secondary tillage. Cone index was a more sensitive indicator of these trafficking effects than was ρb. With the exception of the surface layer (0.0–0.1 m) of untracked interrows, Ks values under NT, as measured in vertically oriented soil cores, exceeded those in CN profiles. Because these tillage effects were not observed when Ks was measured in situ using a permeameter that integrated horizontal and vertical components of Ks, the high Ks measurements from cores were probably produced by flow in vertically oriented macropores although interfacial flow between sample ring and soil cannot be discounted. Untracked NT and CN surface layer macroporosities amounted to 5 and 0% of total porosity, respectively. Macropores did exist below the surface of the tilled layer, but they were susceptible to destruction by wheel traffic. However, tillage did not affect tile drain performance.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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