Previsão de atributos do clima e do rendimento de grãos de milho na região Centro-Sul do Brasil / Forecast of climatic features and corn grain yield in the Brazilian Center-South region

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

Crop forecast has become an important tool for the private and public agricultural policies to be established. Generally, crop forecast is composed by climatic forecast and the yield estimative of growth of economically interesting parts of crops. The climatic forecast can be performed through the analyses of historical series of the climatic features and of the known phenomena, such as the El Niño Southern Oscillation (ENSO), which can be measured by the Southern Oscillation Index (IOS). It can also be done through a numerical integration of differential equations that rule the atmospheric movements of the Earth, a.k.a. numerical forecast. The estimate of crop yields can also be done through the statistical analysis of historical series or through the integration of differential equations that rule the plant physiology and development, both known as crop models. The main objective of this study was to indicate a methodology for Crop Forecast in Brazil, having as a starting point and prototype the study of corn grain yield in the Center-South region of Brazil. Thus, historical series of 60 years of precipitation in 24 sites of the studied region were compared to the IOS measured in the same period, inferring that the phenomenon ENSO has a remarkable effect, distinctly in the most southern and northeast portions of the studied region. One concluded due to the impossibility of using the IOS for daily climatic forecast, which is threatened by the lack of historical series of climatic features with 60 or more years in Brazil. Regarding the climatic forecast, the forecasts of solar radiation maximum and minimum temperatures and air moisture generated by the model Eta on every 6 hours between July 16, 1997 and June 15, 2002 were compared to the respective daily measurements of these climatic parameters. This provided subsidies for the conclusion that the data generated by the model Eta could be used in the Crop Forecast, except for the most southern and northeast regions in the Center-South region of Brazil. For the estimate of corn grain yield, a model based in the integration of equations that rule the plant physiology and development was proposed. Comparing corn grain yields estimated in 24 sites from the agricultural year 1997/98 to 2001/02, one concluded the possibility of estimating the corn grain yield for the studied region by the proposed model. Although the differences between the estimated and the measured yields in the most southern sites and in those with sandy soils indicate the demand for correction of the estimative of water dynamics performed by the proposed model. As a general conclusion, the methodology proposed for crop forecasting brings positive points which should be explored in the sense of its implementation in Brazil. On the other hand, this implementation depends substantially on the work management, propitiating the necessary conditions. One should highlight that the country has developed notably in this sector, such as the cases of the implementation of the national meteorological net and of the knowledge broadcasted by the Center of Climatic Studies and Forecasting and by the The Brazilian Agricultural Research Corporation (EMBRAPA), among other institutions. Even though, this area of knowledge - vital to an agricultural country as Brazil - demands more research.

ASSUNTO(S)

crop forecast simulação - estatística climatic forecast milho climatologia safra - previsão crop modeling grãos

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