Cropand Soil Status As Indicated By Electrical Conductivity Surveys Ofa Field With Cover Cropand Manure Amendments

Animal manure can be an important resource in providing soil available N for crop plant needs.<br>Management of animal manure to match crop needs throughout the crop growing season is one<br>challenge for sustainable agriculture. This study was conducted to examine changes in electromagnetic<br>(EM) soil conductivity and available N levels over three growing seasons in relation to manure/compost<br>application and use of a green winter cover crop. A series (weekly surveys) of soil conductivity maps of<br>a research cornfield were generated using global positioning system (GPS) and EM induction methods<br>with simultaneous soil samples. The study site was treated over a ten-year period with a rye (Secale<br>cereale L.) winter cover crop and no-cover crop. The cornfield research site was split for sub-treatments<br>of manure and compost at rates matching either the P or the N requirements of silage corn (Zea mays<br>L.). Sequential measurement of profile weighted soil electrical conductivity (ECa) was effective in<br>identifying the dynamic changes in plant-available soil N, as affected by animal manure and N fertilizer<br>treatments, during three corn growing seasons. This method also clearly identified the effectiveness of<br>cover crops in minimizing levels of available soil N before and after the corn growing season, when<br>nitrate is most subject to loss. The EM method for assessing soil condition provides insights into the<br>dynamics of available N transformations that are supported by soil chemical analyses. This real-time<br>monitoring approach could also be useful to farmers in enhancing N use efficiencies of cropping<br>management systems, and in minimizing N losses to the environment.