Sugarcane crop effi ciency in two growing seasons in São Paulo State, Brazil

A conceptual framework for crop production effi ciency was derived using thermodynamic effi ciency concept, in order to generate a tool for performance evaluation of agricultural systems and to quantify the interference of determining factors on this performance. In Thermodynamics, effi ciency is the ratio between the output and input of energy. To establish this relationship in agricultural systems, it was assumed that the input energy is represented by the attainable crop yield, as predicted through simulation models based on environmental variables. The method of FAO’s agroecological zones was applied to the assessment of the attainable sugarcane yield, while Instituto Brasileiro de Geografi a e Estatística (IBGE) data were used as observed yield. Sugarcane effi ciency production in São Paulo state was evaluated in two growing seasons, and its correlation with some physical factors that regulate production was calculated. A strong relationship was identifi ed between crop production effi ciency and soil aptitude. This allowed inferring the effect of agribusiness factors on crop production effi ciency. The relationships between production effi ciency and climatic variables were also quantifi ed and indicated that solar radiation, annual rainfall, water defi ciency, and maximum air temperature are the main factors affecting the sugarcane production effi ciency.