Soil and humanity: Culture, civilization, livelihood and health

Abstract

Soil is closely connected to the culture and civilization of an ethnic group living in a given place, including their religion, thoughts, livelihood and health. It is important for people to protect the soil, their agriculture and the environment because the collapse of soil leads to the collapse of human culture, civilization, livelihood and health. The links between the soil and culture, civilization, livelihood and health may result from the ethical attitudes people have about the soil and that they demonstrate through their interactions with it. However, soil resources have been overexploited in modern society and are currently on the verge of collapsing. In this review article, the etymology of words for soil, the place of soil in philosophy and religion, the relationships between soil and the soul, the soil and dialects, and cultural soil science are discussed. The powerful influences of soil on civilization and livelihood are discussed and the relationship between soil and human beings is also considered. Soil can be shown to be a living thing, and this review will present a brief history of the relationship between soil and human health, and will discuss the importance of adopting an ethical attitude towards soil.

Key words:

• etymology
• living soil
• religion
• soil culture theory
• spirits

Introduction

Soil science has traditionally been studied from the viewpoints of soil formation (i.e. classification) and agricultural production. With rising environmental concerns in recent years, however, more research is being conducted on the connection of soils to ecosystems and material cycles, and new disciplines, such as soil ecology and environmental soil science, have been developed. Because soil forms the uppermost layer of the earth’s crust, it is included in research areas covered by geology, geomorphology and physical geography. From the perspective of the environment and the material cycle on a global scale, soil can also been regarded as the pedosphere, in a similar sense as the atmosphere, crustal sphere, hydrosphere, biosphere and anthroposphere.

Researchers in fields such as agromedicine (Journal of Agromedicine) and geological medicine or geomedicine (Lag 1990) have shown that soil, as it relates to topography, geology and agriculture, is intimately connected to human health. And a considerable amount of research and education is currently being conducted in this area. In Japan, educational and research activities have just begun integrating the concepts of soil, agriculture and medicine in the larger environmental context (Minami 2009).

In addition to being studied as part of the natural sciences, soil is also closely connected to the culture and civilization of the ethnic groups living in a certain place, including their philosophy, religion, livelihood and health. In this review article, I discuss the etymology of words for soil, the place of soil in philosophy and religion, the relationships between soil and the soul, soil and dialects, and cultural soil science. I also discuss the powerful influences of soil on civilization and livelihood and then consider the relationship between soil and human beings. Finally, I suggest briefly that soil can be shown to be a living thing, and I will present a brief history of the relationship between soil and human health, and discuss the importance of adopting an ethical attitude to soil.

Definitions

Throughout history, soil has given birth to and fostered a variety of cultures, civilizations and livelihoods. Over time, beliefs and knowledge about soil and related phenomena have flowed from divine and religious perspectives towards a more scientific perspective. Concepts of soil have been born out of literature and poetry in harmony with the way people exist in nature and society via the interaction of economics with science and technology. To aid readers in understanding the terms used in this article, I will present definitions of several key words.

Soil

A traditional scientific definition of soil, as articulated in textbooks, encyclopedias and dictionaries, is the top layer of the earth in which plants grow. In this review, however, I will discuss soil from a social and cultural viewpoint.

As will be discussed in more detail later, the ancient Chinese definition of the two-character (tu and rang) compound for “soil” can be found in “Soil Classification and Land Utilization in Ancient China” (Lin 1996). According to this definition, the first character, tu, means soil in its natural state unaltered by humans, and the second, rang, is farming soil that people broke into soft earth for the purpose of cultivating plants (Fig. 1). Thus, the ancient Chinese definition covered soil in both its natural and agricultural states.

Culture

Culture originally meant cultivating the soil and raising crops. Culture is therefore inseparable from soil. Over time, the concept became more abstract and began to include both the physical, intellectual and spiritual products derived from altering nature. Therefore, culture includes not only food, clothing and shelter, but also technology, academia, art, morality, religion, politics, and other livelihood-shaping modes.

Civilization

Civilization pertains to a society in which the standard of living has been raised, owing to advances in the means of production, and in which principles such as respect for human rights and equal opportunity are recognized. In contrast to culture, which has a narrower sense in the form of religion, morality, learning, art and other spiritual aspects, civilization includes technological and material aspects.

Figure 1 Chinese characters and the pronunciation of Chinese and Japanese relevant to soil.

Livelihood

Livelihood is the means of adapting to an environment and acquiring or securing food, clothing and shelter. It involves producing things and living off this production. The Japanese word for livelihood (Fig. 1d) contains the concepts of birth and growth, and originally indicated the production of agricultural products. Over time, the definition expanded to include everything that is done for one’s livelihood.

Health

Health most commonly signifies the state of one’s body, but it also applies to one’s mental and spiritual state. Being healthy means that there is nothing wrong with any part of the body and that one is well and strong.

Soil and cultures

The etymology of tu (soil)

The central concept of the Chinese ideogram tu (Fig. 1a) is neither the economic “land” nor the material “properties” of soil. As we can see from the oldest Chinese dictionary Shuowen Jiezi (written during the Han Dynasty), tu is strictly that which fosters life. The Han scholar Xu Shen (AD 58–147) explained in the dictionary that tu is “that which produces all things from the land” (Lin 1996).

Tu is expressed as follows. The two horizontal lines represent the ground surface and underground. In other words, soil is the layer between the upper line representing the meeting of the atmosphere and soil and the lower line indicating the bottom of the root development zone. The vertical line shows a plant growing from underground to above ground. The character tu (Fig. 1b; “emit”) in the Shuowen Jiezi is pronounced the same in Chinese as the character for soil and signifies bringing something forth in nature (Lin 1996).

The Han scholar Zheng Xuan (AD 127–200) interpreted the character rang (Fig. 1c) as “soil that people till and use to cultivate plants.” In other words, rang is soil when it is used for farming.

An example in which tu and rang were used together as turang (dojou in Japanese) is the statement “Mt. Tai does not concede its soil [turang], and that is why it is so big; the rivers and oceans do not disdain small flows, and that is why they are so deep” found in the biography of Li Si (280–208 BC) in the Shiji written by the Han historian Sima Qian (145–90 BC) (Lin 1996).

The character tu developed into the characters sheng (Fig. 1d), shi (Fig. 1e) and xing (Fig. 1f). Specifically, tu changed to sheng (Fig. 1d, “a shape showing grass growing, a representation of plants arising out of the soil”), shi (Fig. 1e, “a shape showing plants dividing into branches and leaves, and buds emerging”), and finally advanced to xing (Fig. 1f, “a group related by blood”) (Sirakawa 1996a).

Confucius generally had little to say about nature, but his thoughts on tu are contained in the Chenshu chapter of the book Shuoyuan by the Han scholar Liu Xiang (77–6 BC): “That which is below people is soil [tu]! If you plant seeds, the five grains will grow from it, the birds and beasts will grow from it, living people will establish themselves in it, and the dead will return to it. The soil’s merits are too numerous to mention” (quoted in Lin 1996). It appears that Confucius knew well the greatness of soil.

Soil and spirits

Every ethnic group or region has its own characteristics and great “spirits of the land”. When people are totally colored by these land spirits, it is proof that they are indigenous to that place. According to the reference works Jikun and Jitou by Sirakawa (1995, 1996b),, Japanese tsuchi (written as Chinese tu [Fig. 1a] or di [Fig. 1g]) means “the land” or “(above) the ground”. The Chinese character di is often used in contrast to tian (Fig. 1h; heaven, the sky). Japanese chi means “spirit” (Fig. 1i), whereas tsu is perhaps a vowel ablaut of the character to (Fig. 1j) “place”. Thus, Japanese tsuchi did not signify soil in general, but was a name that called forth something spiritual concealed in the ground. In ancient times there were many occult rites for the spirits of the land.

The ground is linked to blood (chi in Japanese), spirits (hi in Japanese), fire (hi) and the sun (hi), which underpin human life. Hi and chi are etymologically the same. In Japanese the word for soil, tsuchi, tsu indicates the presence of sacred power, whereas chi means spirit or soul. Tsuchi referred to the all-embracing source of sacred spirits and was also believed to be the embryonic source of life.

Only when the land is stimulated by heaven and held by it does the land manifest its power in the form of bountiful productive capacity and bring forth new life. For example, it was believed that rain and wind were proof that heaven and earth have unified, and that thunder and lightning were the effects of this heaven–earth synergy.

What are spirits of the land? In Latin the spirit of a place is called its genius loci. In the Greco-Roman tradition, even if one does not attach the adjective loci (place), a genius was the spirit protecting the land or location, and it controlled the people living there and their fates. In Celtic cultures, the spirits of the soil (dei terreni) are spirits of agriculture that make grains yield well and cows give much milk. They are the guardian spirits of farmers. Australian Aborigines feel that harming the land is harming themselves. Communication with the land by the ancients was based on a totally different perception from that of the present. In Switzerland spirits called gnomes, who look like small old men, were believed to dwell in the soil. According to the Swiss alchemist Paracelsus (AD 1493–1541), they represent one of the four elements (earth, water, wind and fire). Soil-related spirits are also common throughout Asia. Examples are the Ainu kamui, the Ryukyu nirai kanaii, China’s tiandi, Thailand’s phi, and the Philippines’anito.

This consciousness of soil and spirits came to embed itself in concepts such as mythology, religion, ethics, thought and philosophy, and continues its existence in our daily lives. In Japan, libations are ceremonially presented to the spirits of the land at a building site to rid the land of evil spirits before starting the constructions of a house. One still often sees many similar rites in modern Japanese life performed by those who follow the Shinto religion.

Soil and philosophy/religion

Soil has continuously influenced philosophy and religion throughout the world. For example, in ancient Japan, there were many spirits associated with soil (Chamberlain 1973). The famous Outer Shrine of Ise includes separate shrines (betsugu) to the soil and wind. From a modern (scientific) perspective, these shrines are the forerunners of soil science and meteorology.

Fujiwara (1990) reviewed the lineage of deities in Japan associated mainly with soil, primarily Otsuchinokami, based on the book “The Genealogy of the Japanese Gods” by Ken’ichi Kawaguchi, and compiled the results in “Soil and Ancient Japanese Culture”. According to Fujiwara, Otoshigami, a son of Otoshinokami, is the spirit who protects grains. The father–son relationship between the two spirits parallels the close relationship between the soil and grains.

The Chinese ideas of Yin–Yang and Wu Hsing (the five elements) are also related to the soil (Taylor and Choy 2005). In the Hongfan Wuxingzhuan, there is a poem that sings the praises of “soil virtue”:

Trees do not grow or flourish without the soil. Fire has no vigor without soil, and it exists as fire only because there is soil. Metal can become useful when it is put in earthen molds. If there were no soil, water would spill over and never stop flowing; water does not spill over because there are dikes. Soil energy helps new things to sprout and allows that which has weakened to waste away and attain its path. Therefore, the cycle of the five elements is dependent on the power of soil virtue. Soil energy is at the center of seasonal changes, is the driving force behind the seasons, and is the king of the seasons.

Japanese philosopher Shoeki Ando (1703–1762) introduced the unique concept of “soil vitality” (Ando Shoeki Kenkyu Kai 1985). “Soil vitality” is an idea that regards soil as the root substance and that gives substance to soil’s generative power. In other words, soil vitality “advances and retreats” from the above idea of Yin–Yang and the five elements through the stages of the natural generative process and arrives at a “four elements” theory. In the process of cosmos formation (stage 1 of the generative activities), soil vitality emerges as the “soil body” in the “center of the cosmos”, concentrates the energy that circulates throughout the cosmos as “the vitality of the land”, controls the circulation of still more energy, and generates life forms on “the land”.

Furthermore, human beings and the hearths that serve as the venue of their basic livelihoods arise by virtue of soil vitality. Therefore, soil vitality appears in humans and their hearths in substantial form, manifested as “stomach vitality” and “hearth vitality”.

Other systems of thought and religions in which there are close connections with the soil include the Greek theory of the four elements (earth, water, air and fire), the Greek myth of creation (Chaos, Gaia, Tartarus and Eros), the Brahmin Veda of ancient India (Samagana songs and Mother Earth), and the prostrations of Tibetan Buddhism (unification of the mother of the land and spirit of the land).

According to the Old Testament of the Christian Bible, “And the lord god formed man of the dust of the ground, and breathed into his nostrils the breath of life; and man became a living soul”. God made a human (Adam) out of dust and created humans. The term Homo, meaning human, comes from humus, meaning soil. The defining quality of humanity is that after spending their lifetimes working the land, they will return to the land, “for dust thou art, and unto dust shalt thou return” (Genesis 3:17).

Soil and language (Tamil and Japanese examples)

It probably took a mind-boggling length of time and many stages for language to become established in human society. Ono (1981) hypothesized that the Japanese language is rooted in India’s Tamil language. Tamil is spoken in Madras in southern India and in the northern half of Sri Lanka by at least 20 million people. Tamil has the longest history among all of the Dravidian languages, a large family stretching across all of southern India, and by the fourth century at the latest, a considerable body of literature had developed in this region.

Ono (1919–2008) was a pioneer in the use of comparative linguistics between Japanese and Tamil in remote areas to contrast sounds, vowels and consonants between the languages. From the corroboration of conventional linguistic approaches with approaches in other disciplines, such as history, archeology, anthropology, soil science and other agricultural sciences, a close linguistic relationship between Japanese and Tamil emerged.

For example, certain types of soil in Ibaraki Prefecture, Saitama Prefecture and Saga Prefecture in Japan are all known as aka, which refers to the reddish color of the land and places where the soils are rich in iron oxide. This word is derived from akam (farmland) in Tamil.

There appear to be many similar words pertaining to agriculture as well, not just soil. The Japanese hatake (field) is Tamil patukar (farmland) and Japanese tambo (rice paddy) is Tamil fampal (moist soil and marshland). Other similar words in both languages, with Tamil given first and Japanese given second, include the following: jari, jari (gravel); zappa, zampan (leftovers); ni (soil); karai, karu (to mow); kumai, shimmai, (rice offering to the spirits); nuku, nuka (rice bran); uru, uru (to ripen); and urugu, urukasu (to soak in water).

But how did Tamil come to Japan? And what type of words did it leave in China and Korea along the way? Comparative linguistics research would most likely show linguistic impacts concerning soil and agriculture in China, Korea and Japan. If this hypothesis is confirmed, then it is likely that the Tamil words reached Japan through China and Korea.

Soil culture theory

Fujiwara’s (1990)“Soil and Ancient Japanese Culture: In Search of the Roots of Japanese Culture — An Exploratory Discussion on Cultural Soil Science” was a broad and in-depth examination of humanity and soil, farming culture, and soil and culture covering the entire world. He also presented and verified a hypothesis for cultural soil science — that the different types of soil distributed throughout the world have fostered different cultures. Fujiwara wrote, “Because soil is the embodiment of the environment, I believe that cultures come into being with soil as the underlying factor”. Fujiwara categorized the following types of cultures, each of which has soil at their core.

1.	Rice paddy soil cultures: Cultures in which people flood soil to grow wet rice and other paddy crops. This includes ethnic groups in India, Thailand and China (e.g. Yue and Wu).
2.	Loess cultures: Cultures built on loess, which is an alkaline soil. China’s Han ethnic group is one example, producing crops such as barley, wheat and millet.
3.	Oasis soil cultures: Cultures that live in extremely dry oases where soils are alkaline and saline. They include the Uighur, who cultivate fruit trees and vegetables.
4.	Grassland soil cultures: Cultures based primarily on livestock farming, which is viable on dry grasslands. Soils are neutral or alkaline. This group includes nomadic Turkish and Mongolian groups.
5.	Coral limestone soil cultures: Cultures built on red soil consisting basically of the limestone distributed along the southern edges of continents and on islands. This group includes the Austronesian cultures that produce coconut palms, breadfruit trees, banana trees and similar products
6.	Laterite soil cultures: Cultures arising on acidic terra rossa from moist tropical rain forests to savannah regions. This group includes Austroasian sedentary farming cultures that produce crops such as sorghum, cassava, taro and yams.
7.	Red-yellow soil cultures: Cultures arising on the acidic red-yellow soil of moist warm-temperate or subtropical regions. These South-East Asian cultures engage in slash-and-burn agriculture, and ethnic groups such as the Yao, Lahu and Lisu plant crops including dry rice, millet and mulberries.
8.	Brown forest soil cultures, volcanic ash soil cultures: Cultures built on acidic brown forest soils arising in moist temperate-zone regions. This group engages in slash-and-burn agriculture in South-East Asia and includes Tungusic peoples who opened broadleaf deciduous forests. Crops include buckwheat and Japanese barnyard millet.
9.	Podsol cultures: Cultures arising in lands with highly acidic podsols in moist cool-temperate zones and subpolar zones. This group includes the hunting and fishing cultures of Siberian ethnic groups, such as the Buryats and Tuvans, who speak Altaic languages.

Because different cultures arise from different soils, humans live in many different ways and will likely continue to do so. More in-depth research is needed on cultural soil science in conjunction with civilization, the environment and other areas.

Soil and literature

Soil makes an appearance in many works of literature. In the Kojiki, which describes Japan’s creation, there is a passage reading, “He built a hall 48 feet long without doors, entered, and sealed the wall by applying soil” (Chamberlain (trans) 1973, p. 712). In the Manyoshu, Japan’s oldest poetry collection, there is a poem by Yamanoue no Okura reading, “You can do what you like when you go to heaven, but since this is the earth and the Emperor is present, you cannot act selfishly” (Honda 1967, p. 783). Soil also appears often in historically valuable documents, including the Manyoshu and Taketori Monogatari (10th century) of Japanese literature.

An example of a Japanese literary work on “soil” is the novel Tsuchi by Takashi Nagatsuka (1879–1915) (Nagatsuka & Waswo (trans) 1989). Both in title and content it is about soil itself and enables the reader to observe the history of erosion of volcanic ash soil in the Kanto-region loam at the time the novel was written. Although it depicts the hopeless situation of farmers who must make a living from this soil, one also sees the stoutness and cheerfulness of the farmers whose fortunes are bound with the soil.

Kenjiro Tokutomi (1868–1927), who wrote under the pseudonym Roka Tokutomi, was a contemporary of Nagatsuka and wrote an essay entitled “Ramblings of a Worm” (Tokutomi 1938). We can sense of his feelings about the link between soil and life from the passage, “We are born above the soil, live by eating things produced by the soil, and after dying become soil. We are, in the final analysis, soil in a different form. The most suitable work for beings that are soil in a different form must be working the soil. Of all the ways to make a living, farming is the best that one can choose”.

Kenji Miyazawa (1896–1933), an internationally well-known poet and writer of imaginary tales, was a graduate of the soil science department of the Morioka Vocational School of Agriculture. Soil appears often in his literary works. Although not literature, Miyazawa’s graduation thesis was “The Value to Plants of Inorganic Constituents in Humus” (Miyazawa 1957).

Many famous literary works from around the world also select soil as a subject. Émile Zola’s (1840–1902) work La Terre (The Earth) is set in his native France and uses the land in its very title (Zola & Parmee (trans) 1980). Zola uses earthy expressions to depict the peasants’ love for the land and soil. “The Good Earth,” a novel set in China and written by American Pearl Buck (1892–1973), admirably expressed the way that people love the soil and live with it, beautifully and ephemerally (Buck 2004). Don Quixote by Spain’s Miguel de Cervantes (1547–1616) is a story of the experiences of a man from La Mancha (arid land) (Cervantes & Harrison (trans) 2002). “Wuthering Heights” (Brontë 1994), a novel by the English writer Emily Brontë (1818–1848), is the story of a hill on the heath where in the winter it is not desolate and in the summer it is not awe-inspiring, typical vegetation for places with podsols. Les nourritures terrestres (Fruits of the Earth), a novel written by the French author André Gide (1869–1951), overflows with the beauty of the land, ways of living that create the land, and praise for the land (Gide 2002). The works of the Russian writer Fyodor Dostoevsky (1821–1881) feature scenes depicting characters kissing the land. In his novel (The Brothers Karamazov), the character Ilyusha kisses the land (Dostoevsky et al. 2003) and the character Raskolnikov in (Crime and Punishment) kisses the land at a crossroad to atone for the crime of homicide (Dostoevsky & Monas (trans) 2006), exemplifying the Russian belief in Mother Earth. France’s Antoine de Saint Exupéry (1900–1944) is most famous for his work Le Petit Prince (The Little Prince) (Saint-Exupery & Howard (trans) 2000), but another outstanding work is Terre des Hommes (Wind, Sand and Stars), which begins, “The land will teach us human beings more about ourselves than thousands of books… That is because the land resists us” (Saint-Exupery and Galantière (2002))..” And the book ends with, “It is only when the wind of the spirit blows over the clay that humans are imagined.”

Poets also invoke the soil in their works. The English romantic poet William Wordsworth (1770–1850) grew up in the Lake District of western England surrounded by its splendid natural environment and wrote many poems in praise of the land and nature. The German poet Rainer Rilke (1875–1926) fully expressed the land in terms of both life and death. The line “the land is my true love” in the poem “The Flight of Cranes” by the Indian poet and Nobel Laureate Rabindranath Tagore (1861–1941) exudes a love of the land that led Tagore to, among other things, create the Institute for Rural Reconstruction.

Writers throughout the world have long expressed the way humans live with the soil and the land and thereby helped to show the deep relationship between soil and culture.

Degradation of soil and the collapse of civilization

Carter and Dale (1974), Seymour and Girardet (1986), Diamond (2005) and Montgomery (2007) examined the impacts of human activities on soil and the environment. In discussing these works, it is important to keep the future of soil and civilization in mind as we consider the past degradation of soil and civilizations.

The evidence presented in these books shows that the degradation of soil was a key factor in the collapse of various civilizations. Why did the Greeks fall in a mere 30–40 generations? Like other societies, they depended on agriculture to feed themselves. However, as they increased crop production because of population growth, they plundered soil fertility and abetted soil erosion. As a consequence, the soil resources were exhausted and ecosystem destruction proceeded. When Greece was strong, it was still able to prosper, despite the degraded soil, by using its colonies for food production. However, when deprived of its colonies, Greek civilization rapidly declined, suggesting that the progress of civilization is limited by the extent to which it can plunder soil resources from nature.

Concerns that Greece would lose its soil appear in Plato’s dialog Critia (Bury 1960). His description of the logging of Attica’s forests and the impacts of agriculture is powerful writing even today. “The land was the best in the world, and was therefore able in those days to support a vast army, raised from the surrounding people. Even the remnant of Attica which now exists may compare with any region in the world for the variety and excellence of its fruits and the suitableness of its pastures to every sort of animal, which proves what I am saying; but in those days the country was fair as now and yielded far more abundant produce… as in the case of small islands, all the richer and softer parts of the soil having fallen away, and the mere skeleton of the land being left” (Seymour and Girardet 1986).

Montgomery (2007) introduced several studies of soil erosion associated with the rise and subsequent decline of civilizations in the Middle East, Greece, Rome and Mesoamerica, as well as others around the globe. The destruction of Roman civilization was caused by a soil collapse (Carter & Dale 1974), and the decline of Mesopotamian civilization was also accelerated by soil degradation, a result of the accumulation of salts. The increase in salts in Sumerian soil as a result of irrigation was perhaps the first case of chemical contamination in recorded history. The collapse of Easter Island, where the Moai are found, can be seen as an instance of deforestation and its accompanying soil erosion, and Mayan civilization in the Copán valley suffered a similar fate when they cut forests covering the hills, which promoted soil erosion. Of course there were other causes of collapse as well, such as rapid population growth and wars, but as these examples show, the rise and fall of world civilizations are very closely linked to soil.

Diamond (2005) pointed out eight major causes of the process by which past civilizations have precipitated their own environmental collapse. These causes include forest clear-cutting, destruction of vegetation, soil problems, water resource management problems, overhunting, overfishing, pressure on native species by exotic species, and excessive population growth. Although the causes of the collapse of past civilizations are primarily limited to the cutting of forests and soil problems, a complicated mix of all eight causes contributes to current problems. In any case, soil supplies humanity with most of its food and, however it is viewed, the collapse of soil leads to the collapse of civilization.

In the 1840s, the famous German chemist Justus von Liebig (1803–1873) stated that, for the soil to remain fertile, we must return to it everything that has been taken from it. He fundamentally changed the scientific understanding of soil fertility. But instead of heeding Liebig’s caution, humanity has nonchalantly watched as our soil continues to be eroded.

Human beings do not simply eat food. We also “eat” the land. Each bit of soil washed away from slopes denuded by erosion caused by the exploitation of the soil can be considered to be consumed. Forests and grasslands that have been turned into deserts are the combined result of our metabolism. If the soil collapses or is otherwise consumed, civilization as we know it will also collapse.

Agriculture as soil and livelihood

As I have discussed, soil is closely related to civilization and culture. Livelihood is also closely linked to both civilization and culture, and agriculture is the livelihood that is required for humanity’s continued survival.

Agriculture is a bridge between the natural sciences and the social sciences. One could say that it is also the most straightforward, concrete manifestation of the combined effect of humans and the environment. For example, a Japanese word for those who engage in agriculture, hyakusho (farmer) literally means “people who know all about many things”. Farming requires a comprehensive knowledge of natural sciences related to growing crops, including crop physiology, soil, weather, fertilizer and topography. A comprehensive knowledge of social sciences is also required to understand the politics, laws, economics, history, culture, customs and other aspects of the society in which farmers live. As such, agriculture is a comprehensive science whose medium is the soil.

As I have discussed, agriculture as livelihood begot culture and civilization. However, 20th-century agriculture, which has been bewitched by huge developments in science and technology, and by the attendant growth of productivity and population, has completely changed the soil and the environment. In the second half of the 20th century, various sources of energy and types of material have been used to industrialize agriculture. To supply growing populations with food, and to obtain even more abundant food, nutrients have been plundered from the soil and environmental destruction has begun in many countries.

In the next few sections, I will review how soil, by means of livelihood, now influences the human environment.

Disturbance of soil respiration

The pedosphere and atmosphere exchange gases with each other. For example, atmospheric oxygen is absorbed by the pedosphere and pedospheric carbon dioxide is emitted into the atmosphere. Materials in the soil change as a result of the effects of respiration by plant roots, the influence of countless microorganisms living in the soil, and a variety of physical, chemical and biochemical effects, and many gas constituents continually form or disappear in these processes. Just as human beings breathe, the land also breathes.

The healthy workings of this ecosystem have maintained various global systems throughout history, but industrialized agriculture, which appeared in the second half of the 20th century, has begun to disrupt these global systems. Signs of this disruption appear in global warming, which is related to the respiration of the soil and the depletion of the ozone layer. Agriculture is not the sole cause of either of these, but in the present review I will describe the disruption of the soil’s respiration of nitrous oxide caused by the heavy application of nitrogen fertilizer and of methane emission caused by an increase in paddy fields leading to global warming (Minami 2002; Yagi 2002).

A large amount of nitrogen fertilizer is needed to supply food to our growing population. If nitrogen fertilizer was not applied, world food production might fall by half. After nitrogen fertilizer is applied to the soil, it changes to various forms of nitrogen through nitrification and denitrification processes in the soil. One of these forms is nitrous oxide, a gas that, because it does not break down for at least 100 years, moves into the troposphere and stratosphere. Nitrous oxide is both a greenhouse gas and an ozone-depleting gas (Minami 2002). In contrast, the methane emitted from paddy fields also accelerates global warming (Yagi 2002).

Soil erosion

Modern Western society and societies that have adopted its philosophy are consuming precious plant nutrients from the soil at a tremendous rate. We have long refused to recycle waste, as Liebig (Carter and Dale 1974) advocated, and have continued allowing many elements to become environmental pollutants. We continue to apply excessive amounts of inorganic fertilizer and agrochemicals to farmland and pollute the atmosphere, groundwater and rivers. At the same time, in North America, in Asia’s river basins, in the broad expanse of Russia, and in almost every other place in the world, the soil is being lost.

World food production has doubled over the past 30 years. To maintain this level of production, people have brought steep slopes under cultivation and have grown crops such as corn and wheat repeatedly on hilly land where soil erosion is apt to occur. As a consequence, soil erosion has accelerated in both developed and developing countries. Since the mid-20th century, the amount of irrigated land has more than doubled and the use of fertilizers has increased ninefold. These increases have hidden the impact of soil erosion on the land’s productivity (Brown 1996), but run-off has exceeded the formation of new soil on cultivated land.

Deforestation also plays a part in soil erosion. As a result of deforestation for the purposes of slash-and-burn farming or pasturing, much soil is carried from the denuded land into bodies of water during the rainy season. In particular, in tropical forests, which have a very thin soil layer, the increase in ground surface temperature very easily decomposes the organic matter in the soil of cleared areas, leading to severe nutrient losses, and heavy rainfalls readily wash away both the soil and the nutrients.

Soil erosion is occurring worldwide. The amount of soil eroded annually per hectare is estimated to be 5–10 t in Africa, 10–20 t in the EC, North America and Australia, and 30 t in Asia (Brown 1996). Because a mere 1 t of soil is created per hectare annually, these soil erosion rates are shocking. In addition, it has been reported that the average thickness of that 1 t of soil formed annually per hectare is at most a mere 0.1 mm, which means that it takes more than 100 years for 1 cm of soil to form, that is, the rate of soil run-off far exceeds the rate of soil formation. Moreover, in the past 50 years, as a result of urbanization and land degradation, the amount of cultivated land per person has decreased from 930 to 480 m² (Brown 1996, 2004; Montgomery 2007).

Soil salinization

Irrigation has played a decisively important role in coping with the rapid population growth that has occurred since the start of the 20th century. Irrigation, however, which is carried out on a vast scale, cannot help but have a seriously deleterious impact on global water resources and on the farmland on which those resources are used.

Irrigation has had serious impacts not only on the soil, but also on the surrounding environment, including falling water tables, polluted aquifers and the destruction of habitat for aquatic organisms. If an irrigated area is not linked to a proper drainage system, the water table can rise. Crop roots become starved of oxygen, slowing growth. When arid places are irrigated, the water that is near the ground surface sometimes evaporates into the atmosphere, leaving salts in the soil, which lower crop yields. The remaining saline soil has a much lower productive capacity.

There are no accurate data on how much land worldwide has been affected by salinization. There are reports, however, of reduced yields owing to salinization from India, the United States, China, Kazakhstan, and other countries (Brown and Kane 1994). The soil salinization resulting from irrigation in connection with the Kara Kum Canal in Turkmenistan, which occurred in conjunction with the drying up of the Syr Darya, is a good example of how human technology can ruin the soil.

Desertification

Desertification, a specific form of land degradation, is a process by which the land’s productivity is gradually impaired by causes such as excessive use of the land, inappropriate land management and overgrazing. One should not call to mind places such as the Sahara Desert or Gobi Desert when considering the process of desertification. Rather, desertification occurs when land is made barren in a broader sense as a result of human activities.

Some of the main causes of land degradation are overgrazing of rangelands, over cultivation of arable land, flooding and salinization of irrigated land, and clear cutting of forests, all of which are examples of excessive pressure put on the land by human activities or by inappropriate land management.

Irreversible desertification claims more than 6 million ha of land each year worldwide or approximately twice the land area of Belgium. Furthermore, an additional 20 million ha of land becomes so unproductive each year that the land is no longer suitable as farmland (Brown 1989; Squires 2002).

Underlying this problem is the reality that the material cycle between the land and the people living on it is broken. The people living on this land are the victims of soil degradation, and the soil of that land was sacrificed by the people living there.

In the final analysis, soil degradation is primarily the result of excessive human pressure on a land area. To conserve precious soil resources for future generations, current levels of population growth must be reduced. If population growth continues at present rates, Africa’s lands will have to feed many more people than they do now. The same is true in other regions of rapid population growth, including India and the Philippines. Soil degradation will continue until population pressure is alleviated.

Other problems

Other factors, including contamination with heavy metals, urbanization, industrialization and road building, contribute to the relentless soil attrition. Not only is rich soil being lost to salinization, excess fertilizer application and desertification, but soil is also lost through heavy metal contamination, excessive pesticide application and other factors. Here, I will briefly discuss the problem of contamination by trace elements, including heavy metals.

Modern civilization is dependent on the use of large amounts of heavy metals. History shows a close relationship between humanity’s development and metals. People were using copper (Cu) by 6000 BC, lead (Pb) by 5000 BC and zinc (Zn) and mercury (Hg) by 500 BC. Beginning with the Industrial Revolution in the 19th century, heavy metals became even more indispensable to modern society, and we continue to depend on them today.

Growth in the world population, and the attendant increase in the use of heavy metals, will result in still more of these elements being released into the environment. This will cause a variety of problems for the ecosystem and ultimately these heavy metals will accumulate in our bodies via the soil–plant–animal system.

For example, if we assume that the heavy metals mined from the earth’s crust are uniformly spread throughout the world’s 16 × 10¹² m² of farmland, then the soil would have received, per hectare per year, approximately 1.0 g each of cadmium (Cd) and antimony (Sb), approximately 50 g each of Pb, Cu and chromium (Cr), and at least 65 g each of Zn and manganese (Mn) (Nriagu 1979, 1996). These are huge amounts that will probably continue to be sprinkled over all of the soil on Earth unless action is taken to stop mining. Of course, this is the estimation of these metals being returned to the soil. Much of the mined metals will never be returned to the surface because they are permanently or semi-permanently.

The living soil, health and ethics

The current soil crisis is a result of the world’s population having grown beyond 2.5 billion in the latter half of the 20th century. To maintain the growing population, the world’s agricultural system has had to push certain limits. In addition to chemical fertilizers and pesticides, we have become reliant on systems that accelerate and exhaust the productive capacity of the soil. Using various energy and material inputs, we have industrialized agriculture. The material and energy inputs affect production, whereas the soil itself is treated simply as a medium for production. The inherent sustainable productivity of the soil has been disregarded. And now, at the start of the 21st century, the world’s population has grown beyond 6.7 billion.

In response to this situation, we must develop the concept of a “land ethic”, as first proposed in 1949 by Aldo Leopold, the father of American nature conservationism (Leopold 1949). Leopold’s land ethic is a theory in which the conceptual framework of cooperation between people is expanded to cover soil, water, plants and animals, together referred to as “the land”.

If the land is not treated with respect and affection, an ethical relationship with the land cannot be established, and we will not have a truly living relationship with the land.

The idea that soil is a living thing has been widely seen through history, such as when the Greeks referred to the Earth Mother or Gaia. Although human knowledge advances and civilization progresses, this idea has not disappeared. The fundamental characteristics of soil, air and water have changed under the influence of environmental pollution, as has people’s perception of these things. People generally do not accept the idea that soil is a living thing, and they do not protect it. If it can be demonstrated that soil is a living thing, people may be more likely to adopt a land ethic.

Even if “the land is alive” is recited like a religious credo, however, it will not withstand logical inspection if we cannot scientifically substantiate it. Accordingly, in the next section I will look at the potential for living systems theory to tackle this difficult question.

Living systems theory

James Grier Miller (1995) proposed that all living systems are formed of subsystems, each of which takes in, processes and then discharges matter, energy or information, or a combination thereof. He identified 20 critical subsystems that characterize a living system.

The first eight subsystems are processes by which the living system ingests, consumes, utilizes and extrudes matter and energy. The living system is equipped with for a way of taking in matter and energy, known as “ingestion organs”. These subsystems are made up of an ingestor, a distributor, a converter, a producer, matter and energy storage, an extruder, a motor and a supporter.

The next 10 subsystems are processes by which the living system senses its environment and extracts, completes, stores and retrieves information. These are “input transformers”, which bring information into the system. They are made up of an input transducer, an internal transducer, a channel and net, a timer, a decoder, an associator, a memory, a decider, an encoder and an output transducer.

The last two subsystems relate to the processing of both matter and energy and the processing of information in the living system. These are a reproducer and a boundary.

Machines do not generally exhibit this property; they eventually become used up and worn out. In other words, they cannot achieve organic organization.

If the soil satisfies these conditions, then we can say that the soil is a living thing, which is vital if we are to have an ethic of the soil. To substantiate these 20 systems in soil, future research should focus on the nitrogen cycle, which so clearly illustrates the principle of everything being in constant flux. Nitrogen (N₂) is present in nearly unlimited quantities in the atmosphere and its electrical charge freely transforms from positive penta-valency to negative tri-valency. By looking at nitrogen, it should be possible to demonstrate that soil is a living system.

Of course, the necessity of providing a number of different forms of proof is likely to be a major issue in the future. For example, James Lovelock established the Gaia theory of the living earth and earth’s biosphere with numerous forms of proof (Lovelock 1979).

Soil and health

Rudolf Steiner (1861–1925), the esoteric Croatian philosopher and founder of anthroposophy, made the following observation more than a century ago: “So long as one feeds on food from unhealthy soil, the spirit will lack the stamina to free itself from the prison of the body” (Tompkins and Bird 1989). Indeed, as shown in Table1, a number of things that affect soil are very similar to the things that affect humans.

Table 1 Various factors affecting soil and human conditions

Factor	Soil	Humans
Heavy metals	eavy metal pollution	Heavy metal ingestion
Waste materials	Waste dumping	Additive ingestion
Agrichemicals	Excessive application of agrichemicals	Excessive application of medicine
Fertilizers	Excessive use of fertilizers	Excessive ingestion of nutrients
Nutrition	Balance of constituents	Balance of nutrients
Respiration	Healthy gas exchange	Healthy respiration
Chemical substances	Chemical pollution	Chemical ingestion
Healthfulness	Improving fertility	Improving health
Rest	Lying fallow	Sleep

In 1912, Alexis Carrel (1873–1944), the French Nobel Laureate in Physiology and Medicine, said: “Since soil is the basis for all of human life, our only hope for a healthy world rests on re-establishing the harmony in the soil we have disrupted by our modern methods of agronomy. All of life will be either healthy or unhealthy according to the fertility (potential) of the soil” (Tompkins and Bird 1989).

In essence, Carrel was pointing out the close relationships between agriculture, environment and health. Since his statement, soil has continued to be abused and exhausted. Moreover, all types of chemical compounds have been added to the soil. Therefore, it would be difficult to conclude that the soil in general is currently healthy. Consequently, the quality of food produced from the land must be adversely affected, and as a result, our health is also affected. It would not be overstating the matter to say, as Carrel said, that poorly balanced nutrition and harmful ingredients have their origins in the soil. The Japanese have a saying, that “the body and soil are inseparable”. This saying may have first appeared in the Buddhist writings of the White Lotus Sect (Lushan lianzong baojian) of China 700 years ago (1305) or it may have been coined by Tangaku Nishi in 1912 (Amano et al. 2004). The original meaning was probably that “the Buddha-heart” and “the Buddha-land” are inseparable. The saying used to be shared within limited groups of people who had strong concerns about food, geography and health (i.e. as a tradition within families), but the saying has spread to the general population in recent years. It is interpreted as the soil being the body’s life, life being the soil, and the body actually being soil. A broader interpretation also encompasses such sayings as ishoku dougen (food and medicine have the same origin), shihou yonri ni yamai nashi (no sickness within 10 miles in any direction), and chisan chishou (local consumption of local products).

The saying that food and medicine have the same origin has been cultivated over many lifetimes. It is said that it first appeared in the Ishinpou, the oldest medical writings by Tanba no Yasuyori (912–995). According to the Japanese dictionary of Daijirin, the saying represents the idea that medical remedies and ordinary food are both for sustaining human life and maintaining health and so have the same origins.

There can be no doubt that an infant’s health depends on receiving wholesome food in a good environment. The constituents of the soil control the metabolisms of plant, animal and human cells. Apart from illnesses caused by microorganisms and viruses, most illnesses are caused by a loss of harmony between the elements that are necessary for human life, including air, water, soil and food. Among these, the balance of elements in the soil, which is the basis of food, is very important.

Studies on integrating human health and healthy soil have recently been initiated. One example is the International Union of Soil Sciences 18th World Congress of Soil Science, held in Philadelphia, USA, in 2006, in which Commission 4.2, “Soils, food security and human health”, organized the symposium “Soil and human health.”

Geophagy

In 1941, the Journal of the Japanese Society of Soil Science and Plant Nutrition published an article titled “On Geophagy” (Yamada 1941). In describing geophagy, Yamada says, “If you look up the character combination shokudo [“eat-soil”] in Japanese dictionaries, you can find only interpretations such as ‘eating things grown in the soil’ or ‘eat one’s rations’”. By contrast, an English-language dictionary defines geophagy as “the eating of earth, either as a psychotic symptom or to make up for lack of food, as in famine areas”. Merriam–Webster’s collegiate dictionary says “Geophagy is a practice in rural or preindustrial societies of eating earthy substances (as clay) to augment a scanty or mineral-deficient diet. While an abnormal desire to eat substances (as chalk or ashes) is called pica (Merriam-Webster Inc 1993).

Geophagy is widely observed among primates. The reasons that have been given for geophagy by humans include religion, nutrition, mental illness and famine, but there is still room for more scientific research on geophagy in humans.

Yamada’s (1941) article provided several examples of geophagy. “In Chiedomae, Soya County, Kitami Province, Japan, the natives eat a substance like putty which they prepare like meat stew by soaking in water to remove the soil and then cooking. The mud that was removed is cooked with the bulbs of wild lilies, after which it is allowed to stand until the mud precipitates; then they drink the liquid” (Yamada 1941). He also provided examples from other countries: “According to Ehrenberg, it is said that already in 744 AD, the words Steinbrot and Brotstein existed, and in 1807, Alexander von Humbolt wrote that by Lake Orinoco in South America, the natives roasted yellow soil taken from the river bank and ate it. In about the mid-19th century, Heusinger researched geophagy and found that it has a curative significance and that the phenomenon is often seen in places with malaria. Wilken writes that animals eat soil just as human beings do” (Yamada 1941).

Yamada also writes about examples in Peru, Bolivia, Mexico, Sweden, Russia, New Guinea, Spain and Persia.

More recently, Yanai et al. (2009) examined geophagy in Tanzania as a supplement of micronutrients and addressed other geophagy-related issues.

There are three major categories of geophagy: (1) food, famine, and nutrition, (2) superstition, religion and rites, (3) medicines and medical cures. The first two are interesting from the perspective of cultural history, and the third may have implications for basic research on medical applications.

Soil and ethics

The previously discussed links between the soil and culture, civilization, livelihood and health may have been a result of people having a kind of ethical sense about the soil. The necessity of maintaining an ethic of the soil and of the earth should be emphasized because humanity will only be able to permanently stay connected with the soil if we adopt a soil ethic.

Although ethics may primarily be considered by philosophers, ethical questions for the field of soil science should also be considered from the viewpoints of civilization, culture and livelihood. As a consequence, the ethic must not be constrained by the language of philosophy, but rather expressed in the language of environmental sciences, such as soil science and ecology.

Aldo Leopold (1949) wrote the following in The Sand County Almanac: “An ethic, ecologically, is a limitation on freedom of action in the struggle for existence. An ethic, philosophically, is a differentiation of social from anti-social conduct. These are two definitions of one thing. The thing has its origin in the tendency of interdependent individuals or groups to evolve modes of co-operation. The ecologist calls these symbioses. Politics and economics are advanced symbioses in which the original free-for-all competition has been replaced, in part, by co-operative mechanisms with an ethical content”.

Hitherto, agriculture and forestry have been conducted between humans and the soil or the land, but there has been no ethical principle regulating the relationship between the humans and the living animals and plants that depend on the soil and the land. Even now, soil is an object of ownership for humans. Humans and the soil are linked in a completely utilitarian relationship, with humans taking no responsibility for the soil. A host of environmental problems have resulted from this lack of responsibility.

Previous ethical principles have stated that individuals are members of cooperative bodies with mutual dependency. Individuals compete with other individuals to establish their own positions within the cooperative body. However, operating with an ethical attitude, the individual also works in cooperation with other individuals. We must apply this same sort of ethical attitude to the soil and the earth.

Leopold (1949) said, “The land ethic simply enlarges the boundaries of the community to include soils, waters, plants and animals, or collectively: the land. This sounds simple: do we not already sing our love for and obligation to the land of the free and the home of the brave? Yes, but just what and who do we love? It is certainly not the soil”.

The greatest obstacles hindering the development of a land ethic may be the educational and economic structures that currently dominate the world. Instead of instilling a strong awareness of the importance of the land, these structures may pull us in the opposite direction. As a result, we treat the soil and the land only as systems of inorganic materials.

Because of the many processes and tools used in the real world of agriculture of which most of us are unaware, we have become alienated from the soil and the land. People no longer have a living relationship with the soil and land that produced us. Many of us think of the land as nothing more than a space between the cities that produces crops.

It is easy for people living in urban areas to forget that the soil provides the nutrition for life. A convenient and comfortable lifestyle provides no reason to adopt a more profound ethical attitude toward the soil and land. If there is any ethical sense, it is not a sense of ethics for soil and agriculture, but a more convenient ethic for a pretty landscape.

A soil ethic is indispensable for a culture. If a soil ethic does not develop, culture will also not be developed or maintained, and environmental problems will not be solved. A land ethic can be attained as a product of social evolution. The evolution of a soil ethic is an intellectual process similar to the evolution of emotions, by which culture and civilization advance.

As discussed previously in Collapse of Soil and Collapse of Civilization, Diamond (2005) described the appalling results of a lack of a soil ethic. The following passage from Collapse graphically demonstrates our need for a new soil ethic: “About half of the topsoil of Iowa, the state whose agricultural productivity is among the highest in the U.S., has been eroded in the last 150 years. On a recent visit to Iowa, my hosts showed me a churchyard offering a dramatically visible example of those soil losses. A church, built there in the middle of farmland during the 19th century, has been maintained continuously as a church ever since, while the land around it was being farmed. As a result of soil being eroded much more rapidly from fields than from the churchyard, the yard now stands like a little island raised 10 feet above the surrounding sea of farmland”.

Conclusion

Soil is often thought of as little more than dirt, but it is vital for the existence of humans and civilization. It is the soil that, over hundreds of millions of years, an unimaginably long amount of time, created the earth’s biosphere, and it could very easily become worn out in our lifetimes.

Soil is the basis of life, civilization, culture, livelihood and health. If humanity cannot pass healthy soil to the next generation, human cultures cannot be passed on and will surely perish. We do not inherit the land from our parents; we borrow it from our children. If people do not have an ethic for the environment, including the soil, the water and the air, as we have ethics for people and society, the world will surely start to retaliate against humanity. Global warming and soil erosion are good examples. As such, we must promptly adopt ethical attitudes and behaviors with regard to the world.

Acknowledgments

I sincerely thank Professor M. Kimura, Nagoya University, Professor M. Saito, Tohoku University, Dr S. Ono and Dr W. Cheng, National Institute for Agro-Environmental Sciences, for their invaluable and inspiring comments and their corrections to this manuscript. Without their encouragement, this manuscript would not have been accomplished. I also thank Dr H. Narita for valuable assistance.