John Prueger, Jerry Hatfield, Timothy Parkin, and Thomas Sauer. National Soil Tilth Laboratory, 2150 Pammel Drive, Ames, IA 50011-4420
Dynamics of CO2 and H2O vapor exchanges above corn and soybean canopies in rainfed environments provide insights into how these cropping systems respond to the combination of management and meteorological conditions. There is limited information on the C dynamics in these systems which cover the Midwest and are one of the most intense cropping systems in the world. An agricultural production system depends upon C and H2O as two of the primary building blocks yet little is understood about the dynamics of these components over different crops and among growing seasons. A measurement system consisting of energy balance and gas exchange equipment has been installed in a production field that is divided into corn and soybean production systems. These measurements have been made since 1998 for this field on a year-around basis. Data have been quality controlled for this site. Ancillary data on crop growth, yield, and management practices have been recorded for each growing season and crop. There are seasonal changes in the magnitude of the fluxes and the resulting NEE for both corn and soybean. A complete C and H2O balance for the typical cropping systems provide a baseline from which comparisons can be made on the expected changes in C storage that would result from changing management practices.