HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Cassel, D. K. Articles by Nelson, L. A. Search for Related Content PubMed Articles by Cassel, D. K. Articles by Nelson, L. A. Agricola Articles by Cassel, D. K. Articles by Nelson, L. A.

An Evaluation of Mechanical Impedance for Three Tillage Treatments on Norfolk Sandy Loam¹

ABSTRACT

The variability of in situ mechanical impedance in field soils hinders evaluation of impedance differences stemming from various tillage and soil management practices. Use of the penetrometer cone index (CI) is one method to measure mechanical impedance and many CI data have been treated statistically. This study was conducted to evaluate the mechanical impedance as measured by CI for Norfolk sandy loam for the following tillage treatments: (i) moldboard plowing to 22 to 25 cm followed by disking, (ii) chisel plowing to 27 cm, and (iii) subsoiling at 91-cm intervals to a depth of 45 cm followed by bedding. Mechanical impedance was continuously recorded to a depth of 41 cm with a tractor mounted, hydraulically driven, constant rate descent penetrometer at seven positions spaced 15 cm apart on a transect normal to the soybean row. Measurements were taken four times during the year, representing a wide range in soil water content; replicated gravimetric water content measurements were taken as a function of depth at two of the seven positions at the time penetrometer readings were taken.

Analysis of variance showed significant differences in CI for tillage treatment, soil depth, position, and all two-way interactions. Chisel plowing reduced impedance at all seven positions to values less than those measured for the moldboard plowing. Of the three treatments, the subsoiled plots generally had the lowest impedance only in or near the subsoil slit, but had the highest impedance in the trafficked interrow.

We recommend that future characterizations of mechanical impedance (and other soil physical properties which are induced or modified by tillage practices which introduce nonhomogeneity of these properties, i.e., mechanical impedance, water movement, etc.) include sufficient measurements to isolate not only tillage effects, but also position and depth effects.

¹ Contribution from the Dep. of Soil Sci., Biological and Agric. Eng. and Statistics, North Carolina State Univ., Pap. no. 5135 of the Journal Ser. of the North Carolina Agric. Exp. Stn., Raleigh, NC 27607. This study is part of an interdisciplinary research program supported in part by USDA-ARS under Agreement no. 12-14-7001-560.

² Associate Professor of Soil Science, Professor of Biological and Agric. Eng., and Professor of Statistics, North Carolina State Univ., Raleigh, NC 27607.

Received for publication May 31, 1977. Accepted for publication September 6, 1977.