Changes in the Energy Efficiency of Regional Crop Production in Japan

Abstract

Examining agricultural efficiency in terms of energy balance will be a first step in helping to find a solution to the sustainable development of agriculture, and to environmental problems such as the exploitation of natural resources especially in developed countries. This study attempts to define regional energy efficiency based on the regional input-output energy ratio (output/input), which is calculated by the input fossil fuel energy and output food energy of all crops produced in a region. It also investigates the changes in regional energy efficiency of the prefectures in Japan from 1970 to 1990. By inspecting typical combinations of crops, the regional energy efficiency, which will be an index for examining the temporal and spatial changes of regional crop production, is divided into four categories: high (regional input-output energy ratio: more than 2.7 in 1970 and 1990), middle (1.8-2.6 in 1970, 1.7-2.6 in 1990), low (0.7-1.7 in 1970, 0.7-1.6 in 1990) and very low (under 0.6 in 1970 and 1990). Applying these categories to the prefectural level, specific features were seen in the decrease of the prefectures with middle efficiency in the southern Kanto Region and the appearance of prefectures with very low efficiency in the southeastern part of Japan over two decades. It is considered that the decline of energy efficiency was caused mainly due to the increase in the percentage of greenhouse crops planted in the prefectures that are active in the production of paddy rice and horticultural crops. The emergence of the prefectures with very low efficiency in 1990 also implies that intensive crop production reinforces the impact on the natural environment by the usage of fossil fuel energy especially in the region that has high economic land productivity.