Balanço de carbono e energia para uma lavoura de soja: método da covariância dos vórtices turbulentos e a estimativa do modelo CROPGRO-Soybean

• Autor(a) principal: Oliveira, Evandro Chaves de
• Data de Publicação: 2012
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1512
• topic: Carbono; Soja; Modelo CROPGROS-Soybean; Carbon; Soybean; CROPGRO-Soybean; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::AGROMETEOROLOGIA

The objectives of the present work were: 1) to analyze the energy balance and the partition of net radiation into its components of latent heat, sensible heat and soil heat fluxes during the cycle of the soybean crop in the region of Cruz Alta, State of Rio Grande do Sul, 2) to calibrate the simulation model of growth and development, CROPGRO-Soybean (Crop-Environment Resource Synthesis), for soybean cultivar FUNDACEP 53RR, grown in that region, 3) to assess the estimated evapotranspiration of soybeans generated by CROPGRO-Soybean with the data of latent heat flux measured under field conditions by the method of eddy covariance, 4) to test the performance of the CROPGRO-Soybean model to simulate the photosynthetically active radiation use efficiency at different phenological stages of a soybean cultivar grown in the region of Cruz Alta, RS, 5) to evaluate the performance of the CROPGROSoybean DSSAT system integrated in the carbon balance of soybean with the experimental data for flow measurement CO2 by the method of eddy covariance, 6) to analyze the potential impacts of climate change on soybean crop in Rio Grande do Sul, based on CROPGRO-Soybean, a climate change scenario, which includes increasing the concentration of carbon dioxide (CO2). To this end, we used data from field experiments using the technique of eddy covariance conducted in Sulflux Network (Network South Brazilian Surface Flows and Climate Change) in Cruz Alta, Rio Grande do Sul - Brazil (28°36'S, 53°40'W and altitude 409 m) in the 2009/2010 crop year. To analyze the impacts of climate change, we used data from regional climate simulations (HadRM3) to control the climate scenario (1960-1990) and future climate scenarios A2 and B2 (2071-2100) in the CROPGRO- Soybean. The results of this study indicate that the method of eddy covariance was able to reproduce satisfactorily the energy flows above the soybean throughout the experimental period. Through the analysis performed in the simulations, it was found that the CROPGRO-Soybean simulation showed satisfactory results in the occurrence of phenological stages of culture and also on the grain yield, but showed limitations in the estimates of biomass and leaf area index of cultivar Soy evaluated for the conditions of soil and climate of Cruz Alta - RS. The model overestimated evapotranspiration during the crop cycle, probably not realistically represent the residues, indicating a need for adjustments in the parameters of the water balance in soil-tillage. The CROPGRO-Soybean showed good predictive ability of photosynthetically active radiation incident to the conditions, period features and factors considered. The model does not simulate the transport of carbon in the atmosphere, only the production of carbon due to the carbon balance. Therefore, although the model reproduce the general behavior of the flow of carbon, some variations in the daily scale cannot be reproduced. Regarding the impacts of climate change, the results indicate that the increase in grain yield estimate resulted primarily from the projections of CO2 concentration and temperature scenarios for the future, ie, the positive effects resulting from higher concentration of CO2 (CO2 fertilization) was probably the main cause of increased soybean yield in Rio Grande do Sul.