Double cropping - Nimousaku

Japanese: 二毛作 - にもうさく
Double cropping - Nimousaku

This refers to land use where different types of crops are planted twice a year on the same cultivated land. In addition to increasing yields through intensive cultivation management, methods of intensifying agriculture have included increasing the number of plantings and the total cultivated area to expand harvests on limited land. The term "xx years, xx crops" expresses both the land utilization rate and the crop rotation format. For example, rice-wheat planting every year is double cropping with two crops per year, early rice-wheat-late rice-winter fallow is three crops over two years with alternating double cropping and single cropping, and rice-barley-rice-safflower is four crops over two years with double cropping every year, and these have been carried out in response to various regional conditions. A typical example of rice-wheat double cropping in Japan's paddy field agriculture is double cropping with wheat, and rapeseed or milk vetch is also planted as a secondary crop depending on the region.

Weather and soil (water) conditions are major natural and technical factors that restrict double cropping. Cold weather and snowfall restrict the growth of winter crops. The northernmost economical weather limit for rice-wheat double cropping is said to be the region from northern Kanto to Hokuriku. In addition, rice-wheat double cropping combines rice, a flooded crop, in the summer with wheat, a field crop, in the winter. This type of alternating cultivation requires land improvement to dry fields where artificial irrigation and drainage are advanced and water can be controlled. In addition, technical conditions for the development of double cropping include improved varieties that change the growing season and planting period, the use of fertilizers that make it easy to replenish soil fertility, and the use of livestock and mechanization to reduce the labor required for harvesting the previous crop and planting the next crop.

Double cropping is thought to have been quite widespread already in the Kamakura period. After World War II, the area of ​​wheat planted as a second crop on rice paddies was 704,000 hectares in 1957 (Showa 32), but despite technological advances, this fell due to socio-economic factors to 131,000 hectares in 1989 (Heisei 1), and 66,000 hectares in 2000. With the overwhelming majority of part-time farmers cultivating rice as a single crop, Japan's arable land utilization rate was 94.5% (2000). In the meantime, facilities have been put in place on the limited arable land, and triple cropping or more is also practiced.

[Tadao Hatano]

"The Logic of Development of Paddy Field Agriculture" by Hironori Yagi (1983, Nihon Keizai Hyoronsha) " "The Logic of Development of Paddy Field Agriculture" by Takehiko Yoshida (1987, Rural Culture Association) " "The Logic of Development of Regional Integrated Farming - Looking at Regional Farming" by Yukio Nakajima (2000, Agriculture and Forestry Statistics Association)

[Reference item ]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

Japanese:

同じ耕地に、1年に2回、異なった種類の作物を作付けする土地利用をいう。農業を集約化していく方法として、集約的な栽培管理により収量増大を図るほかに、作付回数を増加し延べ作付面積を増やすことによって、限られた土地で収穫量を拡大していくことが行われてきた。「○年○作」という用語法は、土地利用率と輪作形式の両者を表現したもので、たとえば、毎年の稲―麦作付は一年二作の二毛作、早稲(わせ)―麦―晩稲(おくて)―冬休閑は二年三作で二毛作と一毛作の交互実施、稲―大麦―稲―レンゲは二年四作の毎年二毛作であって、地域の諸条件に対応して行われてきたものである。わが国の水田農業における代表的なものとしては、米麦二毛作があり、裏作には麦のほか地域によりナタネやレンゲも作付けられた。

 二毛作を制約する自然的・技術的要因の大きいものとして、気象と土壌(水)条件がある。寒冷・積雪などは冬作の生育を制約する。米麦二毛作の気象条件による経済的北限は、関東北部から北陸にかけての地域といわれてきた。また米麦二毛作では、湛水(たんすい)作物である夏作の稲と、畑作物である冬作の麦とが組み合わされている。この交互栽培には、人工的な灌漑(かんがい)・排水が進み、水の制御が可能な乾田化への土地改良が要件となっている。さらに作物の作季や作付期間を変える品種改良、容易に地力補給を可能にする肥料の使用、前作の収穫と後作の作付けを省力化する畜力化・機械化などが二毛作を発展させる技術的条件である。

 二毛作は鎌倉時代にはすでにかなり普及していたとみられている。第二次世界大戦後では、水田裏作としての麦の作付けをみると、1957年(昭和32)には70万4000ヘクタールであったが、技術の発達にもかかわらず社会経済的要因により減少し、89年(平成1)には13万1000ヘクタール、2000年には6万6000ヘクタールとなった。圧倒的な兼業農家による水稲単作化のもとで、日本の耕地土地利用率は94.5%(2000)である。そうしたなかで、限られた耕地では施設化も行われ、三毛作以上の多毛作も行われている。

[波多野忠雄]

『八木宏典著『水田農業の発展論理』(1983・日本経済評論社)』『吉田武彦著『水田軽視は農業を亡ぼす』(1987・農山漁村文化協会)』『中島征夫著『地域複合農業の展開論理――地域営農をみつめて』(2000・農林統計協会)』

[参照項目] | 一毛作 | 裏作

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