Submitted to: Agriculture Ecosystems and the Environment
Publication Type: Proceedings
Publication Acceptance Date: 7/27/2001
Publication Date: 6/20/2002
Citation: EIGENBERG, R.A., DORAN, J.W., NIENABER, J.A., FERGUSON, R.B., WOODBURY, B.L. ELECTRICAL CONDUCTIVITY MONITORING OF SOIL CONDITION AND PLANT AVAILABLE N WITH ANIMAL MANURE AND A COVER CROP. AGRICULTURE ECOSYSTEMS AND THE ENVIRONMENT 88:183-193. Interpretive Summary: Management methods are needed to use renewable resources, such as animal manure, in ways that benefit both the crop and animal production systems. This study was conducted to determine whether soil conductivity can represent soil nutrient content after manure is applied. A series of soil conductivity maps was made using a global position satellite (GPS) system and electromagnetic (EM) instrument. The EM signal was compared to soil samples collected on a cornfield treated over a seven-year period with manure and compost. After harvest, the cornfield was sown with a winter cover crop (rye). The series of soil conductivity maps made over the crop growing season was effective in identifying manure, compost and cover crop treatments. This method also showed how nutrient levels changed during the growing season. Nutrients became more available to crops after manure or fertilizer was applied. Nutrients were reduced as crops grew. This dynamic measure of nutrient availability helps producers improve the management of cropland fertility. Areas of low fertility can be seen within the field.
Technical Abstract: Development of sustainable agricultural management systems will depend, in part, on our ability to better use renewable resources such as animal manur and to synchronize the levels of soil available N with crop plant needs dur the growing season. This study was conducted to determine whether differenc in electromagnetic (EM) soil conductivity and available N levels over a growing season can be linked to feedlot manure/compost application and use a green winter cover crop. A series of soil conductivity maps of a research cornfield were generated using global positioning system (GPS) and EM induction methods. The study site was treated over a seven-year period wit manure and compost at rates matching either the phosphorus or the nitrogen requirements of silage corn (Zea mays L.). The plot was split for sub- treatments of a rye (Secale cereale L.) winter cover crop and no cover crop Image processing techniques were used to establish electrical conductivity treatment means for each of the growing season surveys. Sequential measurement of profile weighted soil electrical conductivity (ECa) was effective in identifying the dynamic changes in available soil N, as affect by animal manure and N fertilizer treatments, during the corn growing seaso This method also clearly identified the effectiveness of cover crops in minimizing levels of available soil N before and after the corn growing season, when soluble N is most subject to loss. The EM method for assessing soil condition provides insights into the dynamics of available N transformations that are supported by soil chemical analyses. This real-tim monitoring approach could also be useful to farmers in enhancing N use efficiencies of cropping management systems and in minimizing N losses to t environment.