摘要：Brazil has global importance for food production and conservation of natural resources.The country has plans to increase yields and commitments to decrease deforestation that require higher productivity.Plans and policies for the growth of Brazilian agriculture, however, have been made without an integrated analysis of the harvest and not supported by a universal metric regarding its efficiency.Applying methods to model flows of energy and matter along food supply chains for agricultural production from 1975 to 2006, we found that crop and cattle harvests and their productivity have increased during the last four decades in consolidated and deforestation frontier regions.Yet in 2006, crop protein production was 20 times larger than cattle protein, using an area 2.6 times smaller than pastures.Crop protein productivity was 0.25 ton.ha–1 with emissions of 2 ton GHG per ton of protein, while cattle productivity was 0.01 ton.ha–1 with emissions of 283 ton GHG per ton of protein.From 1975 to 2006, the portion of crop protein and energy going to feed increased while the portion going to direct human consumption decreased.Our findings suggest that more efficient food systems would be achieved by a combination of intensification of cattle systems, optimization of feed-meat systems and an increase in the share of the consumption of crops as a source of protein.We suggest an initial road map to the expansion of the cultivated area and intensification of agriculture for zero deforestation, efficient and sustainable land use and food systems where cattle pasture intensification is a transition that will last until the expansion of crops replace all pasture present on suitable arable land.During this transition, pasture area will decrease until it is limited only to marginal non-arable lands.Such change could be achieved by a robust strategy that combines penalties and incentives and prevents the risks of a rebound effect for the intensification of agriculture.
