Soil power - Chiryoku

It refers to the ability of soil to produce crops. However, there is no exact definition of soil fertility, and it is interpreted and used in various ways depending on the country and the person, but the current concept of soil fertility can be roughly summarized as follows. In other words, the concept of soil fertility is an awareness of soil that naturally arose among humans with the beginning of agriculture, and refers to the ability of soil to produce crops. Therefore, soil fertility is the most important property of soil for humans. This soil fertility has the following two aspects. One is the nutrient aspect, which means that in order to achieve high production, nutrients must be supplied to crops in a sufficient, balanced and appropriate manner. The other is the functional and container aspect of the soil, which means that the soil must have the conditions to comprehensively function its physicochemical properties, including fertilizer retention and buffering capacity, physical properties, including the ability to eliminate harmful substances, water retention and drainage functions, and biological properties such as microbial activity. The fertility of a soil is determined by these two aspects. In recent years, the fertility of Japan's soil has declined due to a decrease in the agricultural labor force, which has led to a decrease in the application of organic matter, and the deterioration of the base balance due to excessive fertilization. In 1984, the Soil Fertility Improvement Law was enacted and measures have been taken. The application of organic matter such as compost, proper tilling, and appropriate fertilization are particularly important methods for improving soil fertility.

[Yuki Koyama]

"Commentary on Soil Fertility Improvement Methods" edited by the Soil Fertility Problems Study Group of the Agricultural Products Division of the Agriculture, Sericulture and Horticulture Bureau of the Ministry of Agriculture, Forestry and Fisheries (1985, Chikyusha)" ▽ "German Agricultural Management Theory by Kawanami Takeki - Changing Farming Methods and Maintaining Soil Fertility" (1988, Kyushu University Press) ▽ "Considering the Science of Agriculture and Soil" by Egawa Tomoharu (1992, Yokendou) ▽ "Reviving Soil Fertility - Recommended Soil-Building Farming Methods to Recover Soil Fertility" by Mukushiro Joji (1999, Tachibana Publishing)"

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

作物を生産する土壌の能力のことをいう。しかし地力の正確な定義はなく、国により人により多様に解釈され使用されているが、現在までの地力の概念を集約するとおよそ次のようになろう。すなわち地力という概念は、農業の開始とともに人類に自然的に発生してきた土に対する認識であり、作物の収穫をつくりだしていく土壌の能力をさす。したがって地力とは、人類にとってもっとも重要な土壌の性質である。この地力は次の二つの側面をもっている。その一つは養分的側面であり、高生産をあげるには養分が十分に、しかもバランスよく適切に作物に供給される必要があること。もう一つは土壌の機能的、容器的な側面であり、肥料の保持や緩衝能を含めた物理化学性、有害物の消去性、保水や排水の機能を含めた物理性、そのほか微生物活性などの生物的性質を総合的に機能させることができる条件をもった土壌であること。この二つの側面からその土壌のもつ地力が決定されてくる。近年、農業労働力の減少などで有機物の施用が減り、また、過剰の施肥により塩基バランスが悪化するなど、日本の地力が低下した。1984年（昭和59）に地力増進法が制定され、対策がとられている。地力の改善のためには堆肥(たいひ)などの有機物の施用、的確な耕うん、適正な施肥がとくに重要な手段となっている。

［小山雄生］

『農林水産省農蚕園芸局農産課内地力問題研究会編『地力増進法解説』（1985・地球社）』▽『川波剛毅著『ドイツ農業経営論――農法転換と地力維持』（1988・九州大学出版会）』▽『江川友治著『農と土の科学を考える』（1992・養賢堂）』▽『椋代譲示著『地力はよみがえる――「地力」を回復する土づくり農法のすすめ』（1999・たちばな出版）』

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