Submitted to: American Society of Agri Engineers Special Meetings and Conferences Papers
Publication Type: Other
Publication Acceptance Date: July 19, 1999
Publication Date: N/A
Interpretive Summary: The composition of soil changes as nutrients move into and out of the soil. The movement of nutrients is due to biological and physical agents acting on the soil. Nutrient movement is important to understand contamination risk as well as crop usage of the nutrients. A study was conducted to find whether soil electrical conductivity (a measure of ease of electron flow in nthe soil) can be used to track soil nutrient changes over time. The site used in this study was treated over a six-year period. Manure and compost were applied at rates matching the phosphorus or the nitrogen requirements of the corn. A global positioning satellite (GPS) system and a specialized soil conductivity device were used to produce maps of a research cornfield. Soil conductivity maps were generated at stages within the growing season to follow nutrient application and usage. A computer technique was used to subtract an original map made at the beginning of the year from later maps to remove differences in soil type. This technique improved the statistical interpretation of the data and showed treatment effects early in the season. This method appears to improve the understanding of nutrient movement in the soil and the crop's utilization of these nutrients.
Technical Abstract: Temporal changes in soil composition are of interest in determining nutrient transport in the soil. This study was conducted to determine whether electromagnetic (EM) soil conductivity differences can be linked to feedlot manure application and then be used to trace these differences over a growing season. A series of soil conductivity maps of a research cornfield have been generated using GPS and EM induction methods. The sit used in this study was treated over a six-year period with manure and compost applied at rates matching either the phosphorus or the nitrogen requirements of the corn. The EM maps have been generated at stages within the growing season to reflect nutrient application and usage. Image processing was used to subtract a reference map from subsequent maps to remove cultural, soil and other non-uniformities. This method differentiated (P<0.05) the nitrogen check treatment (commercial application rate) versus manure or compost treatment. Subtracting the bas map also improved statistical interpretation allowing treatments to be identified earlier in the season than based solely on the original image. This paper will present the details of the methods used and the results to date.