*** Question regarding CERES Wheat: I have been attempting to simulate a spring variety of wheat (Triticum aestivum L. cv. Yecora Rojo) planted at a 0.25 m row spacing and grown near Phoenix, Arizona. As the specific cultivar parameters are not available, I have been trying to calibrate the model. After trying several existing varieties, playing with numbers and running GenCalc, I am still unable to obtain acceptable results (I have 3 seasons worth of data). One of the biggest problems is obtaining reasonable predictions of both leaf weight and leaf area index. If I adjust the parameters to obtain predicted leaf weights near the observed, LAI is greatly under predicted. And the reverse is also true (correctly predict LAI, leaf weight is severely over predicted). This leads me to the conclusion that the value used for specific leaf weight (or equivalent parameter) in the model is not appropriate for my variety. I do not see a "species" file for the CERES model. Does anyone know where I could change such a parameter? Or is there some other action I could try? I would also be interested to hear from anyone who has had success in applying CERES Wheat in an arid environment. I am a little concerned in temperature related responses in the model, as the crop temperature can be considerable lower than air temperature due to evaporative cooling. *** Precision farming, remote sensing and crop models On a somewhat different subject, I would also like to hear from anyone planning to use remotely sensed data with crop models. Three major sources of information that can be estimated from remotely sensed data are: 1. Soil properties - Using images in the red and/or near-infrared (NIR) portion of the spectrum to spatially interpolate point soil samples and to identify sampling locations. 2. Canopy density - Spectral response in the red and NIR can be used to derived estimates of LAI using empirical relationships or through canopy models. 3. Evapotranspiration - Application of thermal and reflective data combined with basic meteorological conditions can be used to obtain instantaneous estimates of actual ET. I believe all three could be used in applying crop models to precision farming problems. We are planning to try some different approaches and I'd be interested to find out who else is working in this area. Thanks, Ed Barnes DSSAT class of `96 -------------------------------------------------------------------- Edward M. Barnes, Ph.D. Phone: (602) 379-4356 x 268 Agricultural Engineer Fax: (602) 379-4355 USDA, ARS email: [log in to unmask] U.S. Water Conservation Lab 4331 E. Broadway Rd. Phoenix, AZ 85040 ---------------------------------------------------------------------