Development Orientation of Rice Growing Technique and Various Subjects about the Soil Physics

Abstract

Study subject about soil physical properties, which are necessary for technical development of direct seeding and rice cultivation, are arranged and showed. Land leveling facilitates stand establishment of rice seeding, weed control, and water management for strengthening of lodging tolerance on wet-seeded and water-seeded rice culture. On dry-seeded rice culture, permanent water is applied earlier than before in roder to shorten dry rice field preiod and to decrease frequency of herbicide supply. Land leveling is necessary for dryseeded rice culture, too. Recentry, land leveling technology was developed. It is composed of crawler type tractor, laser controlled plow and leveler. The study on operation method of land leveling to avoid surplus compaction of soil is necessary in future. Development of dike management technique to prevent leakage of water is necessary for rice cultivation without puddling, such as dry-seeded rice culture and no-tilled transplanting rice culture. Farm land consolidation affecting water requirement is important to stabilize the dryseeded rice culture. The study on rice productivity decrease by continuation of no-tilled cultivation is necessary. The water seeding and wet seeding includes three types of seeding-method, i.e., broadcast seeding, stripe seeding and hill seeding. It is necessary to sow rice seed in constant depth for stable establishment of seeding, And, it is important to control the physical properties of puddled soil and to unify them in the paddy field in order to maintain constant sowing depth. The effect of soil properties and puddling method on the puddled soil physical properties should be studied, It is important to avoid the soil compaction and necessary to elucidate the role of organic matter in prevention of compaction when the sustainability of crop production by the large-sized mechanization agriculture is considered in future.