Twice crops of rice a year appeared in the middle of the Edo era owing to the favorable climatic condition to make for the staple food. But a period of decadence set in the end of Edo era and early in the Meiji due to the poor cultivation and the difficulty of the gradeimprovement. Since the middle of Meiji at the first crop the Kinugasa-wasa had been planted from the end of March to the end of July and at the second crop the Hayakawa shu had deen planted from early in August to early in Novemder. And from early in Taisho the management has been kept eqilibrium. Those days the twice crops a year was cultivated on the seashore plains but early in Showa it has been limited to the Kochi-Aki Plain, due to labor problem.
For the twice crops of rice a year the climatic condition is essetial. It can be cultivated by utilization of the possible-climate, optimatic climate and the sunshiny-hour for grow and distribution of the Typhoon. The latter is the direct motive especially. Topography is the second condition. In Kochi Prefecture the rice-farm is scanty due to the mountainious topography, so the intesity of the rice-farm is very high. This geve impitus to appearance of the twice crops of rice a year. But the grade is low, and the fertilizer and the lador are much required. So there is a tendenoy that the second crop has changed in to the realization crop. The agricultural management of the twice crops of rice a year is changing its areal character. The growing area was most large and the crop was high in 7-8th of Showa.
