Journal of the Society of Agricultural Structures, Japan

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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.

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An empirical mathematical model of effective permeability of tube channels and a model based on enzyme kinetics principle for generating respiration rate of ‘Irwin’ mango (Mangifera Indica Linn.) were studied to create a modified atmosphere (MA) package for maintaining the quality during storage. The results showed that the effective permeability of tube channels of 3 to 9mm in diameter and 50 to 350mm in length varied from 7.8×10^-6 to 91.0×10^-6m³/h for O₂ and 7.0×10^-6 to 78.5×10^-6m³/h for CO₂. The multiplicative non-linear model adequately described the effective permeability to tube dimensions with coefficient of determination (R²) of 0.956 and 0.959 for O₂ and CO₂ permeability, respectively. The enzymatic model of respiration rate generated from 12 different gas compositions fitted the experimental data very well. The model package of a 0.0043m³ glass jar with 1.2kg sample (three mangos) using a tube channel of 50mm in length and 9mm or 11mm in diameter attained an equilibrium gas composition of 8.3-11.4%O₂ and 9.6-14.7%CO₂, and showed some improved quality retention within 21 days of storage, while the control fruits were not acceptable after 14 days of storage. The model packages significantly reduced the fruit weight loss and tended to reduce the decline in hardness, SSC and acidity, reduce the incline in pH, and there were no significant changes in visual appearance due to decay incidence. This result suggests that the use of tube channel would be suitable for MA storage of mango.

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