Crop rotation and the rotation effect.

摘要

Crop rotation is a universal management practice that has been recognized and exploited for centuries and is a proven process that increases crop yields. However, past management practices involving multi-crop/multi-year cropping systems have evolved to the current corn (Zea mays L.) -soybean [Glycine max (L.) Merr.] rotation found dominating the Midwest. Increasing acreage of continuous corn is also on the rise due in part to favorable economics. The problem associated with the production of agronomic crops is a decline in yield when any one crop is grown continuously. The reason for this yield decline has not yet been explained.; This dissertation was a multi-disciplinary study designed to evaluate the rotation effect by examining the below ground factors influencing yield potential of corn and to determine the impact of cropping systems on yield and profitability. The research reported in this dissertation is broken into seven chapters beginning with a literature review. The seven chapters are grouped into four areas of emphasis which are: (i) to determine the impact of management systems and crop rotation on corn and soybean response; (ii) evaluation of below ground factors influencing the rotation effect of corn; (iii) the effect of crop rotation on long-term corn yield trends; and (iv) the profitability and risk of multiple cropping systems.; The research contained within this dissertation serves independently to answer specific questions concerning agronomics, economics, and soil ecology, but cooperatively serves to integrate these different areas with regard to cropping system management. This dissertation provides valuable information to help understand why crop rotation works and what drives cropping management decisions, however many questions remain and further research should be done regarding crop rotation and the rotation effect across a range of environmental conditions to fully define the importance of our results in corn production systems. With this information, it is my desire that we are better informed to make sound crop management recommendations and decisions for tomorrow, not only in Wisconsin, but throughout the entire Midwest.