Estimated Dry Biomass for Summer Crops in the Subtropical Zone in Southern Brazil

The objective of this study was to calibrate and validate models to estimate dry biomass of maize and soybean crops in the Campos Gerais region, located in the subtropical zone in southern Brazil, with incident solar radiation (Rs), growing degree days (GDD), days after planting (DAP) and precipitation (P) as variables. The experiments were carried out in the 2006/2007 and 2007/2008 harvests in Castro and Ponta Grossa cities, in four phenological stages, to obtain dry biomass. The climate data came from the ABC Foundation agrometeorological stations, installed close to the experimental areas. The parameters adjustment was performed by the Least Squares Method and using a spreadsheet Solver. The soybean harvests with the highest DAP, Rs, and P until physiological maturation were not the ones that obtained the highest final dry biomass productivity, except for the GDD variable. As sowing was performed later, the soybean crop cycle decreased. With the exception of the models' performance for the precipitation variable (between "Terrible" and "Excellent") for soybean and maize crops, the other variables presented promising performances between "Bad" and "Excellent", with a predominance of "Excellent".