Abstract
To examine the possibility of cultivation on highly compacted soil, tomato and cucumber were grown under three types of soil condition; soil cultivated in a routine manner with ridges; soil cultivated in a routine manner without ridges; soil compacted by paddling without ridges. The hardness of each type soil by Yamanaka’s soil hardness tester was 4-8 mm, 20-24 mm and 25-28 mm, respectively. At the early stage of cultivation, plants cultivated on the soil compacted by paddling required additional watering and the use of liquid fertilizers to achieve the same level of growth as that of the other soil conditions. In accordance with the increased soil hardness, the total yield and the yield of high quality product were increased in cucumber cultivation. In tomatoes a similar increase in the yield of high quality product was also observed. The gaseous phase ratio were remarkably decreased in the plots without ridges, and it was less than 10 % in the soil that was compacted by paddling. The values of an exchangeable base and cation exchange capacity (CEC) at the end of cultivation were highest in the plot with compacted soil. The total root area decreased with the hardness of the soil. However, the distribution of roots in each plot was similar despite the significant difference in physical properties. Cultivation of plants on compacted soil does not require machinery to make ridges, and moreover, there was a remarkable improvement in the efficiency of field labor.
