R. Eigenberg, J. Nienaber, R. Ferguson
Feb 22, 2004
Journal name not available for this finding
Animal manure can be an important resource in providing soil available N for crop plant needs. Management of animal manure to match crop needs throughout the crop growing season is one challenge for sustainable agriculture. This study was conducted to examine changes in electromagnetic (EM) soil conductivity and available N levels over three growing seasons in relation to manure/compost application and use of a green winter cover crop. A series (weekly surveys) of soil conductivity maps of a research cornfield were generated using global positioning system (GPS) and EM induction methods with simultaneous soil samples. The study site was treated over a ten-year period with a rye (Secale cereale L.) winter cover crop and no-cover crop. The cornfield research site was split for sub-treatments of manure and compost at rates matching either the P or the N requirements of silage corn (Zea mays L.). Sequential measurement of profile weighted soil electrical conductivity (ECa) was effective in identifying the dynamic changes in plant-available soil N, as affected by animal manure and N fertilizer treatments, during three corn growing seasons. 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 nitrate 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-time monitoring approach could also be useful to farmers in enhancing N use efficiencies of cropping management systems, and in minimizing N losses to the environment.