経営規模

Japanese agriculture is faced with a number of urgent problems to be solved to strengthen its international competitive power and to secure core farmers. To solve these problems, the Ministry of Agriculture, Forestry and Fisheries had an objective to enlarge the size of rice farming in its New Policies. In this paper, we try to investigate the possibility of attaining this objective from the view point of liquidization of farmland through tenancy. In Section I, we review previous related studies and divide them into two groups. Studies of the first group apply the ordinary cost analysis in which the structure of production cost of rice farming is specified without using continuous mathematical functions. Models of this group are not operational and it is difficult for us to evaluate policies in various ways directly using them. Studies of the second group apply the production function analysis. Models of this group are operational but have such critical weak points as instability of estimated parameter values caused by heterogeneity of production technologies among farms of different size, and impossibility of parameter estimation caused by non-variability of factor prices. Aggregate statistical data compiled for some wide region, land conditions of subregions of which are heterogeneous, are used in studies of both groups to estimate the difference in productivity between small-sized and large-sized farms, and the estimated difference seems to merely show differential rent. Also studies of both groups are for very short period of time. In Section II, based on our review in Section I, we specify an analytical model and deduce the necessary conditions for liquidization of farmland through tenancy. We appliy Kawaguchi-Lee's theoretical model (1993) as a first approach. Their model is operational and can take into consideration the heterogeneity of production technology. In Section III, we estimate the values of parameters of the model introduced in Section II based on the Reports on the Survey on Production Cost of Rice, for the period of 1965 to 1990 and for “A” Prefecture in Kyushu region. Land condition within“A” Prefecture is comparatively homogeneous. Findings of this study are summarized as follows: (i) The estimated parameters are stable throughout the investigated period. This implies that Kawaguchi-Lee’s model as a first approach is valid over a long period of time. (ii) In each year of the period, marginal income and marginal surplus are respectively same among farms which use the same machinery and equipments, irrespective of the size of them for about 25 years. (iii) The above mentioned necessary conditions are fulfilled throughout the investigated period. (iv) The difference in productivity between small-sized and large-sized farms is increasing gradually throughout the period. (v) If the small scattered field system continues to be in existence, and if the economical environment surrounding rice farming continues to be competitive, it seems the possibility that most farmland will be acquired by middle-sized instead of large-sized farms is large, from the stand point of our second finding. It seems to be difficult for farmers to enlarge rapidly the size of rice farming in Japan meeting our expectations.