Sugarcane crop efficiency in the State of São Paulo between growing seasons of 1990/1991 and 2005/2006. / Eficiência da produção agrícola de cana-de-açúcar no Estado de São Paulo entre as safras 1990/1991 e 2005/2006

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

The sugarcane is an important resource for food and energy production with scale to help the economy of fossil fuels and the development of new guidelines for socio-economic development in sustainable basis. The State of São Paulo is a region of great potential to meet the sugarcane demand in terms of sugar, ethanol and energy, since it has a long tradition related to this sector, its economic structure, the available technology and enough infrastructures. The objective of this study was mapping crop efficiency over 16 growing seasons, examining the relative importance of climate and soil and inferring on the socio-economic aspects interfering in the composition of the sugarcane crop efficiency and its spatial and temporal variability. The concept of crop efficiency was derived from the thermodynamics to generate an indicator for evaluating the performance of agricultural production systems in local or regional scale, and measure how factors affect the production system. In thermodynamics, efficiency of a process is given by the ratio between the total energy available and the amount of energy effectively used to achieve the process. To establish the relationship with agricultural systems, acknowledged that the available energy could be estimated by the attainable yield given by simulation models based on environmental variables, while the observed yield could represent the energy effectively used in the process. The method of Agroecological Zones of the FAO was applied to determine the potential yield, adjusting it according to water stress by the Jensen method and the soil constraints according to the concept of the production environment proposed by Prado. Before its implementation, the model was parameterized and validated by comparison with field data. Here, the IBGEs data were taken as observed yield, so then to assess the crop efficiency of sugarcane in the State of São Paulo, analyzing the factors influencing on it. It was observed that the climatic factors explained 43% of the variability of crop efficiency of sugarcane, based on the analysis of the average values from 16 growing seasons. Regarding this point, it was obtained that the following weather elements affect the efficiency of agricultural production, in order of importance: solar radiation, water deficit, maximum temperature, precipitation, and minimum temperature. Regarding the soil, it explained 15% of the variability of the sugarcane crop efficiency, also considering the average of all seasons. Analyzing the temporal variation of this correlation, it was noticed a change in the pattern of correlation from the 2001/2002 season, probably because of the crop expansion to the west of the state during the subsequent period. The consumption of fertilizer was used to support some inferences made in this context. On average, 42% of the variability of efficiency of production of sugarcane in the State of São Paulo was explained by other factors, besides the climate and soil. It was inferred that social and economic aspects have great influence on the composition of the crop efficiency of sugarcane, markedly the prices paid for sugarcane product and the ethanol demand in the internal market.

ASSUNTO(S)

análise de séries temporais cana-de-açúcar clima soil produtividade spatial and temporal variability. climate solos. modelagem de dados modelling yield

ACESSO AO ARTIGO

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