To review some of these land surface changes we will be using the NLDAS dataset. Many land surface interaction parameters are not measured or measured in limited areas, but can be reviewed using the NLDAS dataset. The NLDAS reanalysis dataset, with a spatial resolution of 1/8th of a degree over central North America and a 1 hour time step, has a period of record going back through 1979. We will use this data to find changes in the water balance across the Corn Belt with a specific emphasis in the northern plains where corn has encroached on pasture or other crops. Changes in both the timing and magnitude of seasonal potential evapotranspiration (PET) in response to changes in farming practices, and other climate forcings are expected. Preliminary results may show an increase in PET during the summer months.