Abstract
Dairy farming systems have mainly been evaluated only from economic point of view for long time. This attitude has often caused various environmental problems.
To enable total evaluation two combined evaluation indexes were proposed. One is [Nitrogen Load/Net Agricultural Income] Ratio [kg-N/1, 000yen], which shows how much nitrogen is spread to the environment in the process of dairy production to earn 1, 000yen of net agricultural income. Another is [Fossil Energy Input/Net Agricultural Income] Ratio [MJ/1, 000yen], which shows how much fossil energy is input in the process of dairy production to earn 1, 000yen of net agricultural income.
Although the Energy Output Input Ratio has been used to evaluate agricultural production systems such as rice production systems by Udagawa (1976), this ratio cannot be used either for evaluation of a multi-production system which produces more than two agricultural products, nor for comparison between two agricultural production systems producing different agricultural products. Two combined evaluation indexes proposed here can be used in the evaluation or the comparison above mentioned.
Examples of evaluation using two combined evaluation indexes were conducted on 197 dairy farming systems located Hamanaka-cho, east part of Hokkaido, Japan. It was revealed that large differences in nitrogen load were observed among dairy farming systems having the same net agricultural income, and that [Nitrogen Load/Net Agricultural Income] Ratio can describe the differences totally including environmental aspects among dairy farming systems.
