酪農生産における自給飼料生産労働の評価

抄録

     The purpose of this paper is to examine the current situation of forage production by dairy farmers and to estimate the shadow wage rate for labor related to roughage harvest and preparation.
     The roughage self-sufficiency ratio has been gradually declining since 1980 due to the appreciation of the yen and improvements in production and distribution conditions. Under the New Food, Agriculture and Rural Areas Basic Plan, the roughage self-sufficiency ratio should rise to 100% by FY2020, but the current ratio has stagnated at 78% (FY2009). On the other hand, agricultural figures show that roughage self-production costs have been below the price of imported hay for more than 20 years. This observation is very interesting, because if this is accurate, many dairy farmers could have increased their roughage production. However, roughage output figures do not suggest such a trend.
     The question then arises as to why dairy farmers have been making such an uneconomical choice for so long? One plausible answer is that the construction of the question is wrong and misleading. The agricultural annual report states that the reduction of roughage production results from the labor load associated with its production. To address this problem appropriately, we focus our attention on the shadow wage rate of roughage production and underscore the significance of labor in roughage production.
     Several studies have been conducted on the shadow wage rate in dairy farming. However, due to the lack of data, little attention has been paid to the roughage labor shortage that is a most serious problem in contemporary dairy farming.
     In what follows, we first point out the harsh labor conditions in roughage production. Then, we measure the shadow wage rate for roughage harvest-and-processing labor and compare it to the figure obtained from the current method. We adopt a linear-program model as an analytical tool and calculate Lagrange multipliers for the shadow wage rate. Detailed data on households and dairy operation are gathered from farmers' accounts.
     Our analysis led to the following results. Based on the statistical data, the shadow wage rate of roughage production is 5,954 yen/hour and 6,151yen/hour on 60 cow dairy farms and 100 cow dairy farms, respectively. Based on farmers' managerial data from Shikaoi town in midland Hokkaido, the average shadow wage rate is 4,667 yen/hour. Nevertheless, the official wage in dairy farming is set at 1,619 yen/hour. This figure is too small to be comparable to the figures mentioned above. The reason for this discrepancy is that the average wage rate in secondary industry is considered to be an accurate figure for the dairy sector, despite the differences in the labor conditions.
     In addition, to assess the validity of this wage rate, we estimated an imputed value of the roughage production labor using the harvest commission fee. The result is that the average labor value is 4,859 yen/hour, which is consistent with the previous results.
     We thus conclude that the official wage figure has to be revised to take into consideration the fact that roughage production suffers from a labor shortage.