2006 Annual Report 4d.Progress report. This report serves to document research conducted under a Specific Cooperative Agreement between ARS and the Tennessee Agricultural Experiment Station of the University of Tennessee. Additional details of research can be found in the report for the inhouse research project 6401-21220-001-00D, Cropping Systems Research. A long term soybean tillage experiment was initiated in 1979 comparing three no-tillage and three tilled production systems where yield, soil carbon, nutrient levels, and pest populations are being monitored. The pest level differences being studied include the soybean cyst nematode and charcoal rot. In 2002 one half of each tillage treatment was reversed to the other treatment. Conversion of no-tillage plots to tilled resulted in a significant increase in nematode levels. Cooperative research efforts with USDA-ARS are attempting to explain which biotic and abiotic factors including bacteria, fungi, flagellates, amoeba, and ciliates in the soybean rhizosphere are regulating soybean cyst nematode reproduction. In contrast to previous reports, present data are indicating that the no-tillage systems are dominated by bacteria instead of fungi. Levels of charcoal rot have been measured in soil and on plants on all plots and the data are being analyzed. A variable rate lime study is continuing, evaluating lime and no lime application for soybean production. No yield effects from lime are being observed except where initial pH was below 5.4. Lime is presently recommended when pH is below 6.1. More accurate lime recommendations are needed for variable rate lime application using precision farming technologies. Research is also underway on nitrogen-seeding rate interactions for corn and cotton production on a large field using variable rate technologies for application of nitrogen and the planting of the crops at the various seeding rates. New research has begun to determine nitrogen fertilizer response function for no-tillage corn production to be used in a calculator to determine most economic fertilizer nitrogen application rate. The costs of nitrogen have almost doubled since the last growing season.