ENERGETIC ANALYSIS OF FOUR CROP SEQUENCES IN BUENOS AIRES PROVINCE, ARGENTINA

Abstract

The use of fossil energy in agriculture is an important issue. In fact, fossil energy is a scarce and non-renewable resource, which needs to be preserved for future generations but whose consumption has been linked to global warming. The aim of this work was to analyze the energy flows and evaluate the energy balance (BE) and energy efficiency (EE) of four crop sequences (rotations): oat (Avena sativa L.)/soybean (Glycine max (L.) Merr.), barley (Hordeum distichun L.)/soybean , rapeseed (Brassica napus L.)/soybean, wheat (Triticum aestivum L.)/soybean, produced under two different levels of technological management in Buenos Aires (Argentina). Incoming energy to crop sequences was similar in the two seasons evaluated (13.8 GJ ha-1) but BE and EE were greater in the first season due to better meteorological conditions. Results showed different energy flows, BE and EE in the evaluated sequences. Energy efficiency was high (9.4-17.2) and values decreased gradually for barley/soybean-wheat/soybean-oat/soybean-rapeseed/soybean. The use of a different agro-ecological crop adaptation strategy and the ‘predecessor effect’ on soybean production would count for these differences. Technological management had a lower influence on energy variables compared to crops and growth conditions. Barley/soybean showed the best performance due to its high EE and BE, presenting energy costs that were only a little higher than the other sequences. It is important to fully evaluate these productive options by incorporating other indicators of ecological sustainability, as well as economic and social aspects of sustainability.