The evalution and the proof of farming systematized techniques with crop rotation which is mainly composed of potato [Solanum tuberosum], and with mechanization on the heavy clay soil farm-zone in Nagasaki [Japan]

1. For the future direction of potato producing area, we think: (1) Introducing new farming techniques to realize labor savings and cost effectiveness based on regional cooperation, e.g. land improvement. (2) Linking with protected agriculture. (3) Improving high-value addedpotato production. Further, construction of a regional agriculture system is needed, which includes effective land utilization after land improvement; raising a new farming generation; keeping enough employer on busy farming season reducing production costs; labor savings and lightening the labor; managing agricultural machinery cooperatives; and managing organizations that are trusting and which in turn are trusted. 2. We tested each crop for quality of product in a reddish yellow heavy clay-based farmland using sorghum as a green fertilizer in crop rotations of spring potatoes with winter carrots and spring potatoes with fall-winter Japanese radishes. The total crop and the quality of winter carrots, fall-winter Japanese radishes, and spring potatoes were improved when sorghum was planted after harvesting spring potatoes or when plowed with approximately 2 ons of green sorghum per 10 ares of farmland before planting winter carrots and fall-winter Japanese radishes. Appearances of common scab for the spring potatoes were reduced more when a green fertilizer was used in the crop rotations of spring potatoes with the winter carrots and spring potatoes with fall-winter Japanese radishes than when 1.5 tons of barnyard manure was used on every 10 ares of farmland. The pH value of the soil did not rise and was kept low when a green fertilizer was used, though using barnyard manure involves raising of a pH value of the soil. We chose Green Sorghum, one of the fastest growing sorghums, to be planted after harvesting spring potatoes, and 5kg of nitrogen fertilizer was given in the case of medium-rich soil as initial manure per 10 ares. The sorghum seeds were planted twice as dense as regular planting, so that the yield was 2 tons of sorghum per 10 ares in forty days. In the case of planting in rich soil, 4 tons of sorghum was harvested from each 10 ares in 30 - 40 days by regular sowing and without giving any extra manure. 40 days after the planting, the sorghum was soft and watery so that it was easy to mash and plow in 3 - 4 times of rotary plowing. 3. Reduction of labor and planting time were studied by using mulching with slits for spring potato budding. It took two people 5 hours and 57 minutes per 10 ares to cut ordinary clear mulch film without holes, however, mulching with slits accomplished the task in a quarter of the time, 1 hour and 37 minutes. Mulching with slits did not raise the temperature of the soil and thus the harvest by early planting was low, but this harvest equaled or exceeded late planting, as in the middle of February. 4. Seeding using the seed plates helped reduce the labor for thinning carrots. Suitable size of the seed plates for this purpose should be 8mm. Watering facilities are required to increase the ratio of germination of carrots in a heavy clayish soil field. The results of the study show that we can get almost the same harvest and quality of winter carrots without thinning as with it in heavy clayish soil if we use seed tapes with seeds placed every 5cm, covering with dry cut straw, and watering twice before budding by high performance watering tubes for a total of 15mm if no rain occurs. 5. We studied the feasibility of using seed tapes for reducing labor when seeding Japanese radishes. The Two-Row Seeding Machine of the Nagasaki Prefecture Agriculture Experiment Station can accomplish 0.45hr/10a and is 5 - 6 times as effective as a manual seeding machine (2.6hr/10a). No problem was found in the budding and growing of plants planted with the seed tapes, and greater harvest yield was obtained. 6. The labor for spring potato mulching farming in improved fields in the heavy clayish area can be reduced to 45 hours per 10 ares, i.e. 30% increase in efficiency, by using high performance farm machines, such as a semi-automatic potato planter, a riding cultivator, and a self-propelled potato harvester. 7. Labor for winter carrots farming in improved fields in the clayish area can be reduced to 43 hours per 10 ares, i.e. 60% increased efficiency, by using high performance farming machines, like tape seeder produced by the Nagasaki Prefecture Agriculture Experiment Station, a riding cultivator, and a self-propelled carrot harvester. 8. Labor for spring potatoes, winter carrots, and fall-winter Japanese radishes can be reduced 12 - 62% by introducing mechanization. This also has the effect of improving farmers working posture, releasing them from carrying heavy loads, and reducing seed and seedling cost. This also requires farmers to co-operative use farming machinery to use co-operative sorting house. 9. We made farming models of 5ha and 3ha with crop rotation which is mainly composed of Potato, and with mechanization. In the case of the 5ha farming model, agricultural income can reach to \13,000,000 with a total working time of 5,700 hours and the 3 ha farming model, \7,300,000 with 3,400 hours, by reducing costs by co-operative use farming machinery and getting enough labor during the busy seasons between May to June, and October to December.