Dear all I am Harikrishna working on maize simulation model in relation to different N doses and 4 slplits of N for each N doses. When I run the model the predicted yield level will be satisfactory but the yield respone for the split application of N at critical stages of crop will be zero. So when I calibrate few values in CO2-X- axis and CO2-Y axis in the maize species (MZCER 980.SPE) file, model predicted accurately yield levels of maize for split application of N, at critical stages of crop growth. The calibration of MZCER980.SPE what I followed is valid or not, if not please suggest the correct way of calibration. Yours Harikrishna ___________________________________________________ Click below to experience Sooraj R Barjatya's latest offering 'Main Prem Ki Diwani Hoon' starring Hrithik, Abhishek & Kareena http://www.mpkdh.com