ABSTRACT

It may be asked whether all of the transformations that have been seen in farming have improved or, on the other hand, worsened energy efciency in agrarian systems. This is an essential question in a panorama of growing economic and environmental difculties facing agriculture, which is increasingly dependent on fossil fuel and under greater threat from the effects of climate change. The purpose of this chapter is to discuss the most appropriate means of measuring the energy efciency of the management of agroecosystems. To do so, it is essential to change the traditional focus that confuses agroecosystems with cultivated land, leaving aside other spaces in the territory which are fundamental, and segment the energy ¥ows within the territory to an extent that makes their analysis impossible. In this chapter, then, we rst offer a description of how energy ¥ows circulate through agroecosystems. As a combination of biotic and abiotic components, they show evolutionary features

CONTENTS

2.1 Introduction .................................................................................................... 33 2.2 Energy through Agroecosystems ....................................................................34 2.3 Internal Loops and Territorial Costs .............................................................. 37 2.4 Metabolic Process of Appropriation: A Wide Denition of

Agroecosystem ...............................................................................................40 2.5 Metabolic Approach to Energy Analysis of Agroecosystems ........................ 43 2.6 Breaking Down the Biomass Flows in Agroecosystems ................................ 45

2.6.1 The Input Side .....................................................................................46 2.6.2 Inside Agroecosystems .......................................................................46 2.6.3 The Output Side ..................................................................................48