Abstract
This study was designed to calibrate and test an agrometeorological model over 18 growing seasons in three soybean production areas in Brazil: Passo Fundo (Rio Grande do Sul State), Londrina (Parana State), and Dourados (Mato Grosso do Sul State). The soybean potential yield (Yp) was determined by two methods: estimated using the FAO Agroecological Zone Model or based on the maximum yield published by the Brazilian Institute of Geography and Statistics (IBGE), increased by 10, 20 and 30%. The estimate of actual yield (Ya) was calculated by correcting Yp for the relative water deficit at different growth stages. The results showed that the best performance was obtained when the Yp was represented by the maximum yield increased by a certain percentage. The model showed satisfactory Ya estimates for the three locations, generating R 2 values of 0.64, 0.46 and 0.70, with mean absolute errors (MAE) of 303, 289 and 259 kg ha -1 for Passo Fundo, Londrina and Dourados, respectively. In a global analysis, the performance of the model was satisfactory, with an R 2 , agreement modified index (d 1 ), confidence index (C) and MAE of 0.64, 0.52, 0.71 and 300 kg ha -1 , respectively.
Highlights
Agriculture is an important part of the Brazilian economy, in particular the jobs, income and revenues that are generated through the export of agricultural commodities
This study used daily meteorological data obtained during the period from 1990 to 2007 for the variables of maximum and minimum air temperature (°C), sunshine hours and rainfall in Passo Fundo, Rio Grande do Sul State (28°15'46"S, 52°24'24"W, 684 m), Londrina, Paraná State (23°08'47"S, 51o19'11"W, 610 m) and Dourados, Mato Grosso do Sul State (22°13'18"S, 54°48'23"W, 430 m), which are traditional regions for soybean production in Brazil
The second method assumed that Yp would be the highest value observed (YmO) in the historical series published by IBGE (1990-2007), increased by Agrometeorological model for soybean yield
Summary
Agriculture is an important part of the Brazilian economy, in particular the jobs, income and revenues that are generated through the export of agricultural commodities. In a modern and global agriculture, increases in crop yield as well as the assessment of climate risk systems define the capacity of a country to become competitive in the international market (EMBRAPA, 2006). Soybeans are the most important Brazilian agricultural commodity. To improve the methods for estimating soybean yield and production, there. Agronomy is a need for technologies that make cropforecasting systems more accurate. According to Oliveira et al (2003), the official agencies responsible for gathering information about agricultural crop yields are still using subjective methods, such as interviews with farmers and agrochemical/fertilizer sales representatives
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