In this research, in order to clarify ecological significance of the levees in flatland paddy fields, the habitat density of the frog, Rana porosa porosa on each levee type was investigated. The investigation was conducted in the Isawa area in the southern part of the Iwate pref. in the early summer in 2002. The number of Rana porosa porosa in the paddy fields that were rearranged to large units in the recent years, has decreased. It has been suggested that the disappearance of traditional earth waterways and the reduction of levees might have caused the decrease of the frog species in the paddy fields. Our research shows that on the levees attached to waterways the number of the frog species significantly varies according to the material that is used for the waterway. That is, the number becomes smaller when it was altered to concrete from the naked soil. At the same time, we did not find any significant difference in the amount of food for this frog species between in the concrete waterways and in the earth waterways. This suggests that the amount of food does not cause the discrepancy between the number of the frog species in the concrete waterways and the number of one in the earth waterways. On the levees between the paddy fields in the area that was consolidated before the recent consolidation, the number of the frog species considerably varies according the moisture condition of the area. This indicates the importance of levees as pieces of land in water, narrow walkways between paddy fields that are filled with water. As opposed to the levees between paddy fields, the levees attached to earth waterways hold high density of the frog species. This verifies that Rana porosa porosa have an affinity to the levees attached to the earth waterways. The significant factors of how this frog species choose what kind of levees to frequent, are more structural, i.e., the structural changes of the paddy fields that are caused by the modern farmland consolidation, the existence of attaching waterways and the material of the waterways, than administrative, i.e., water management and weeding. Also, we verified that the amount of food is not especially a regulative factor in terms of the density of the frog species on the levees.

View full abstract

The conditions of the rice-growing farmers in Japan become much severer in recent years, so that it is difficult for most small-and medium-sized farmers to continue farming and to properly maintain their farmland in most areas. Establishment of a collective farming system at community level is one of the most hopeful measures to improve their labor productivity and cost saving. Future perspective of the community agriculture is important information to accelerate the establishment of collective farming association.
Applying the Multi-Agent Systems (MAS), we have developed a new simulation model named “Agent-based Simulation Model for Agricultural Planning (ASMAP)” that can properly deal with both farmland lease and contract operations of farming among the farmers in a community. It is a completely-revised version of our previous model (CALL model) that can deal with farmland lease only. The ASMAP can predict future agricultural structure of the community and the area of abandoned farmland under the given conditions. We believe this model can bring about a lot of essential information for agricultural planning at community level that the previous model cannot provide.
We applied the ASMAP to the community of one-hundred farm households in Kanzaki Town, Hyogo Prefecture and verified some behaviors of the model outputs. We found the model has enough accuracy by comparing the simulation results with the actual observations.
We also conducted the analysis on the effects of collective farming association and found it is quite effective to decrease the area of abandoned cultivation. At the last, we pointed out some issues for diffusion of the program package of the model.

View full abstract

To clarify the measures for increasing permanent residents in rural areas, we evaluated the population migration of the young, by analyzing the net migration rate until the young group aged 15-19 years becomes 25-29 years old after 10 years in 44 municipalities in Kyoto Prefecture. This period correspond that of employment, advancing to the next stage of education, and marriage. The following results were obtained. 1) The general trend of “moving from rural areas to cities” was more predominant in females than in males. 2) The influences of the geographical condition of municipalities (distance from Kyoto City) on population migration have been gradually decreasing. 3) A significant correlation was observed between modernization of the sewage system and the migration of the young population (p<0.05 in the males and p<0.01 in the females). 4) In the females, even after excluding the influences of the geographical condition, a significant correlation was observed between modernization of the sewage system and population migration (p<0.05). Observation 2) was obtained by the following procedure. First, scatter diagrams were produced by plotting population migration (migration rate) in each period (1965-1975, 1970-1980, …, 1990-2000) on the y-axis and the geographical condition of each municipality (distance from Kyoto City) on the x-axis. Second, the linear function, y=ax+b and the logarithmic function, y=a · ln(x)+b were applied to each scatter diagram. Observation 4) was obtained using the partial correlation coefficient, not the correlation coefficient.

View full abstract

Following the Uruguay Round Agreements on Agriculture, the price stabilization policy for agricultural products has been reduced gradually in Japan and will be so in the future, which will have significant impact on the agricultural structure in Japan.
This paper examines the relationship between the price fluctuation rate of agricultural products and the risk premium in investment in farming land, in order to clarify how the price stabilization policy affects future trend of agricultural production in Japan.
Using the multiple regression analysis, this paper analyses the correlation of the risk premium in investment in farming land as a criterion variable with the price fluctuation rate, the ratio of business farm household, and an agricultural area-classified dummy as explanatory variables.
Consequently, there is a tendency that the risk premium is higher if 1) the price fluctuation rate in a certain area is higher, 2) the ratio of business farm household is higher, and 3) when (or if) it is in the mountainous areas.
The result indicates that farmers tend to choose the risk premium according to the price fluctuation rate of agricultural products in an attempt to avoid risk of price change. In addition, instability in farmer's income affected by the price fluctuation rate is likely to differ, depending on the population of part-time farmers or geographical conditions.
The result is also consistent with the “relationship between the expected rate of return and the risk premium” in terms of the asset pricing theory. Theoretically, farmland price is determined as a result of division of net return of land by expected rate of return. In this regard, our finding of this paper indicates that the smaller the price fluctuation rate of products is, the smaller the expected rate of return, therefore, the higher the farmland price tends to be.
This paper suggests, therefore, that the price stabilization policy of agricultural products tends to raise farmland price, hindering the distribution of farmland; thus, we can conclude that abolishing the price stabilization policy contributes into fall of farmland price.

View full abstract