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Experimental Design - Main Field Site
Much of the KBS LTER research effort is concentrated on the main experimental site, a 60 ha site that has been subdivided into seven different 1-ha cropping systems, each replicated in one of six blocks, with an eighth never-tilled system nearby. Four of these eight systems are annual crop rotations, two are perennial, and two are successional systems in native vegetation, as diagrammed in the main site layout map at left.
The annual crops are corn - soybean - wheat rotations. Treatments 1 and 2 receive standard levels of chemical inputs, with Treatment 1 chisel plowed and Treatment 2 under no-till management. Treatments 3 and 4 are organic-based low chemical input systems with a winter leguminous cover crop; Treatment 3 receives banded herbicide and starter N at planting, and Treatment 4 (certified oganic) receives no chemical inputs at any time. Both T3 and T4 receive additional post-planting cultivation and T4 is rotary-hoed to control weeds. Click on the image for a printable map of the study area.
The perennial systems include continuous alfalfa (Treatment 6) and trees (Treatment 5), the latter planted to a fast growing Populus clone on a10-year rotation cycle. Treatment 7 is a native successional treatment, abandoned after spring plowing in 1989. Treatment 8 is a never plowed site, 200 meters (m) south of the others, that serves as an historical control for soil organic matter studies. Individual plots contain subplots established to address specific process level hypotheses (e.g., +/ fertilizer, +/ herbicides, different planting densities). Each plot also contains a permanent set of 5 sampling stations, at which most within-plot sampling is performed.