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

This Article Abstract Full Text Free Full Text (PDF) Free 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 Eigenberg, R. A. Articles by Ferguson, R. B. Search for Related Content PubMed Articles by Eigenberg, R. A. Articles by Ferguson, R. B. Agricola Articles by Eigenberg, R. A. Articles by Ferguson, R. B. Related Collections Nitrogen Electromagnetic Induction, EMI Cover Crops Nutrient Management

Soil Conductivity as a Measure of Soil and Crop Status—A Four-Year Summary

^a USDA-ARS, U.S. Meat Animal Research Center, P.O. Box 166, Clay Center, NE 68933
^b Univ. of Nebraska, Lincoln, NE

View larger version (44K): [in a new window]   Fig. 1. Split plot design with four replicates of main plot (cover and no-cover) and subplots (manure and compost applied at either the N or P needs of the silage corn crop, as well as commercial fertilizer). Soil cores were taken in Replicate 2 (+). Treatments are designated MN, manure at crop requirement nitrogen rate; CN, compost at crop requirement nitrogen rate; MP, manure at crop requirement phosphorus rate; CP, compost at crop requirement phosphorus rate; and NCK, a commercial fertilizer check. +CC indicates winter wheat cover and –CC is no-cover.

View larger version (17K): [in a new window]   Fig. 2. (a) Soil conductivity meter response showing normalized sensitivity for Geonics EM-38 and Dualem-2. This figure also indicates depths of thermocouple soil temperature probe locations in relation to normalized sensitivity of the EM-38. (b) Soil conductivity meter normalized cumulative response for both Geonics EM-38 and Dualem-2 (http://www.dualem.com/gsem.htm, verified 23 Mar. 2006). This figure also indicates normalized cumulative response relative to the soil core depth of 0.3 m used for this study; cumulative response at 0.3 m was >50% for the EM-38 and nearly 30% for Dualem-2.

View larger version (25K): [in a new window]   Fig. 3. (a) Soil temperature correction for Dualem-2 based on soil thermal profile to 315 cm (mean values of 2002 and 2003) developed from Dualem-2 response curves (Fig. 2a). (b) Soil temperature demonstrated predictable temperature patterns (2002 and 2003) that allowed temperature corrections to be estimated for the Geonics instrument response profile based on 2002 and 2003 data.

View larger version (28K): [in a new window]   Fig. 4. A four year summary of soil temperatures during the growing season. Soil temperatures shown to 45 cm for 2000 and 2001. Thermocouple grid was installed (2002) to 315 cm with representative measurements shown at 45, 95, and 315 cm.

View larger version (30K): [in a new window]   Fig. 5. (a) Soil nitrate measurements taken on apparent electrical conductivity (ECa) survey dates. Comparison is shown for winter wheat cover crop and no-cover for the four year study. All values are taken from Replicate 2. (b) Water-filled pore space (WFPS) measurements on ECa survey dates. Comparison is shown for winter wheat cover crop and no-cover for the 4-yr study. Mean of differences of no-cover minus cover demonstrate a water deficit of cover compared with no-cover for the 4-yr study. All values are taken from Replicate 2.

View larger version (81K): [in a new window]   Fig. 6. Representative apparent soil conductivity (ECa) map as generated on 17 June 2002. Soil conductivity map is overlaid with treatment symbols.

View larger version (28K): [in a new window]   Fig. 7. Apparent electrical conductivity (ECa) by treatment for no winter wheat cover crop. Treatments are designated MN, manure at crop requirement nitrogen rate; CN, compost at crop requirement nitrogen rate; MP, manure at crop requirement phosphorus rate; CP, compost at crop requirement phosphorus rate; and NCK, a commercial fertilizer check.

View larger version (27K): [in a new window]   Fig. 8. Apparent electrical conductivity (ECa) for the main treatment of winter wheat cover and no-cover during 2000, 2001, 2002, and 2003. Asterisks indicate survey dates when the mean values of cover and no-cover were not significantly different (P > 0.05).

View larger version (39K): [in a new window]   Fig. 9. Apparent electrical conductivity (ECa) for subtreatments and for no winter wheat cover (–CC). Subtreatments are designated MN, manure at crop requirement nitrogen rate; CN, compost at crop requirement nitrogen rate; MP, manure at crop requirement phosphorus rate; CP, compost at crop requirement phosphorus rate; and NCK, a commercial fertilizer check. An asterisk indicates a survey date when the mean values of manure or compost and the commercial fertilizer treatment were not significantly different (P > 0.05).

View larger version (37K): [in a new window]   Fig. 10. Apparent electrical conductivity (ECa) for sub treatments and for winter wheat cover crop (+CC). Subtreatments are designated MN, manure at crop requirement nitrogen rate; CN, compost at crop requirement nitrogen rate; MP, manure at crop requirement phosphorus rate; CP, compost at crop requirement phosphorus rate; and NCK, a commercial fertilizer check. An asterisk indicates a survey date when the mean values of manure or compost and the commercial fertilizer treatment were not significantly different (P > 0.05).

View larger version (26K): [in a new window]   Fig. 11. Distinctive shapes of the apparent electrical conductivity (ECa) mean values (averaged across all treatments and subtreatments) shown with chronological events for each season. M/C, manure or compost; NCK, commercial fertilizer check.