Change in Soybean Productivity and Its Trend in Japan: Measurement by the Tornqvist Index

Abstract

The total factor productivity (TFP) of soybean production in Japan was measured by the Tornqvist index. The TFP value increased gradually for the last 40 years, while soybean yield per unit area continued to decrease. The yield decreases could possibly be attributed to observed drastic decreases in labor input per unit area with increases in scale of production. The results indicated that 1) soybean farmers adopted scale-expanding, labor-saving production techniques and 2) yield-improving techniques adopted by the farmers did not have enough effects in compensating for the yield decreases. Further analyses are required to clarify and confirm these hypotheses.