![\"\"](\"https:\/\/healthist.net\/en\/wp-content\/uploads\/sites\/3\/2026\/03\/296_en_feature01_01_fig01.png\")
<\/small><\/p>\nFigure 1. <\/span>The structure of clay<\/span><\/strong>The structure of a clay mineral (mica, in this example) consisting of silicon and aluminum. An oxide of aluminum (Al) is sandwiched between two layers of silicon (Si) forming a structure reminiscent of rugby players in a scrum. Potassium ions (K+<\/sup>) and cesium ions (Cs+<\/sup>) that are similar in size to the spaces between the silicon layers cling tightly to them, increasing viscosity.<\/p>\n<\/div>\n Earth originally had no soil, just like the Moon and Mars. However, after components of rock that dissolved in rainwater became concentrated and formed microparticles, organisms began to become active, and the surface environment of Earth gradually started to change. This was 500 million years ago, 4.1 billion years after Earth’s birth. Microorganisms and plants grew and died. The majority of their remains returned to the atmosphere in the form of CO2<\/sub>, but about 1% remained in the ground without decomposing. This tiny amount of residue built up over thousands, then tens of thousands of years to form soil containing organic matter (Figure 2).<\/p>\n Figure 2. <\/span>The composition of soil<\/span><\/strong>Dead leaves fall onto the ground (❶), where they are broken down by a diverse array of microorganisms. Most are released into the atmosphere in the form of CO2<\/sub>, but the minute quantity of microorganism “leftovers” becomes soil (❷, ❸).<\/p>\n<\/div>\n In soil science, soil is defined as a substance with a complex structure that consists of a mixture of mineral components produced from the disintegration of rocks, organic matter from organisms, and innumerable microorganisms. As biological activity also takes place in soil, it could be described as the very essence of an environment, in which formation and decomposition are constantly taking place at the same time.<\/p>\n On Earth, the term “soil” principally refers to the layer from the surface to a depth of around 1–2 m. Generally speaking, this is the extent of the soil layer containing a mixture of weathered rock and the remains of dead flora and fauna. Soil is the site of activity for microorganisms, worms, and plant roots, as distinct from the rock mass (bedrock) below it (Figure 3).<\/p>\n Figure 3. <\/span>Earth’s structure and its soil layer<\/span><\/strong>Soil is a resource that exists on only a very thin part of Earth’s surface.<\/p>\n<\/div>\n NASA is undertaking research into the creation of soil on Mars and the Moon, with an eye to humankind living in space one day. In space, where there are no living organisms, it will be necessary to create a cyclical process by first introducing and cultivating resilient plants such as mosses, then having microorganisms break their remains down after they die, and mixing the organic matter with minerals.<\/p>\n However, there are no microorganisms in space. Having obtained material developed by NASA to replicate the sand on Mars and the Moon, we, too, are conducting research using moss that survived in space (as proven by a team led by Professor Tomomichi Fujita of Hokkaido University) to find out what kind of microorganisms need to be added in order to produce soil, but it is not easy. The biggest reason why nobody has managed to establish a technology for producing soil artificially from scratch is the complexity of the microorganisms in soil. Scientists say there are at least 10 billion bacteria in a single tablespoon of soil, and at least 10,000 different species of microorganisms. It is only when those 10,000 or more different microorganisms are collaborating while undertaking their own specialized tasks that the remains of dead plants can decompose. We are still studying what kind of microorganisms we need to select. It is still very rare to find bacteria like Bacillus subtilis<\/i> var. natto<\/i> and Lactobacillus<\/i> that can be removed on their own from the natural world and used for human purposes—such bacteria account for less than 1% of all bacterial species.<\/p>\n Another crucial feature of soil is its structure. Soil is not merely a mass of small particles; it is a three-dimensional structure produced as a result of the secretions of microorganisms, clay minerals, and organic matter becoming entangled and forming links to each other. This is called an aggregated structure. Within that aggregated structure are numerous gaps that retain air and water (Figure 4). This structure develops further through worms and other soil fauna eating soil and then excreting it as feces. Soil in which this mechanism is widespread achieves a good balance between drainage and moisture retention capacity. If microorganisms that can only survive inside this structure are removed from soil, they cease to function as they should.<\/p>\n Figure 4. <\/span>Aggregated structure<\/span><\/strong>The difference between soil with an aggregated structure and soil without. The soil on the left has maintained its aggregated structure and is soft, with an abundance of gaps between the particles. In the soil on the right, the aggregated structure has broken down, leaving it hard and densely packed. This structural difference has a major impact on plants growth.<\/p>\n<\/div>\n Looking at the potting soil sold at garden centers, people tend to think that humans are able to artificially produce soil. However, this is actually nothing more than a blend created by gathering soil that already existed. Nobody has managed to make soil artificially as yet.<\/p>\n Soil and sand are important resources. For example, high-purity “eleven-nine” (i.e. a purity level of 99.999999999%) silicon dioxide is required for the silicon wafers used in semiconductor production. As the silicon in Japanese sand is bonded to aluminum, making it unsuitable for semiconductor production, Japan is reliant on imports of high-purity sand from China. No matter how advanced our semiconductor manufacturing technology is, we face the problem that the sand used as a raw material does not exist in Japan. On the other hand, sand is also consumed in large quantities as a construction material. Sand is produced every year, as mountain rocks weather and are deposited in rivers and along coasts, but the demand for concrete, which is made from sand, is twice that amount, with the result that supply cannot keep up.<\/p>\n In Japanese soil, meanwhile, aluminum is bonded to silicon, and a huge amount of energy is required to separate them. This is why we cannot manufacture aluminum from domestic raw materials alone, and are dependent on imported bauxite to meet most of our needs. The fact that Japan recycles a large volume of aluminum cans is closely connected to this lack of domestic aluminum resources.<\/p>\n Soil’s greatest role as a resource is in food production. Somewhere in the region of 95–98% of the food we eat originates from soil. As well as vegetables, of course, even beef traces its origins back to the soil, as cows eat grass, which grows in soil. The plant factories that have become the focus of attention of late have the advantage of allowing water and nutrients to be reused, but they require a great deal of energy and the crops that can be cultivated in them are limited to high-priced leafy salad vegetables. Open-field agriculture that enables us to harness sunlight, rain, and microbial action is essential to support our staple daily diet.<\/p>\n Japan depends on imports for most foodstuffs, which at the same time means it is reliant on overseas soil in this regard, too. The temporary suspension of French fry sales at fast food outlets a few years ago was symbolic of this issue. The potatoes we eat every day in Japan are supported by the fertile soil of Canada and the U.S. If that region is hit by drought, flooding, or insufficient sunlight, crop yields will fall, leading to the risk of French fries disappearing from menus.<\/p>\n The same applies to dairy farming. People tend to think of Hokkaido when dairy products are mentioned, but much of the feed consumed by dairy cows is imported from overseas. If a forest fire breaks out in Canada’s permafrost zone and the smoke leads to insufficient sunlight during its short summer, grass production on its southern prairies will fall. Further south, corn and soybeans will not grow even in the fertile soil of the U.S. if there is a shortage of water. Environmental changes of this kind are directly linked to dairy farming in Japan, and will lead to rises in the prices of cheese and butter. In other words, Japanese dining tables are closely connected to the soil environments of far-off lands.<\/p>\n According to researchers, the fertile black soil used as agricultural land across the globe increases by just 1 cm or so every 100 years—in other words, it hardly increases at all during the span of a human life. On the other hand, black soil is rapidly being lost as a result of overcultivation and excessive development, as well as deforestation. Much of the wheat used in Japan is imported from countries such as Canada and the U.S. Until around a century ago, a thick layer of this fertile black soil lay beneath the grasslands of that region. However, plowing of the land to turn it into fields for wheat and corn caused the black soil to decrease due to wind erosion and decomposition, and scientists say it is now less than half as thick as it used to be. As soil’s resilience cannot be seen from the surface, desertification—the process in which soil degradation causes yields to gradually decrease—progresses before we know it. It only becomes apparent when yields fall, but in quite a few cases, recovery is difficult once that resilience has been used up.<\/p>\n Furthermore, North America is a water-scarce region, so groundwater is pumped up for agricultural use, but as groundwater in areas that were formerly on the sea floor has a high salt content, accumulation of salt in the topsoil leads to salinization, which inhibits plant growth and can cause plants to wither and die. Studies have shown that salt accumulation causes an area of farmland equivalent to that of Iwate Prefecture to fall into disuse every year—this equates to one soccer pitch every 15 seconds. The fertile soil that nature has built up over such a long period is being used up to produce our food.<\/p>\n The deforestation of the Amazon rainforest is another serious problem. Rich virgin forest is increasingly being replaced by agricultural land consisting of red soil with few nutrients. Cattle farmed there are imported into Japan, along with pigs and chickens fed on corn and soybeans grown there. The deforestation of the Amazon rainforest is connected to our food system all the way over here in Japan. Tropical rainforests have also been cleared in Southeast Asia, so that corn and other crops could be cultivated on the fertile topsoil, which has a thickness of just 3 cm or so. As a result, only yellow, clay-rich soil remains. This has caused a vicious circle in which neighboring areas of tropical rainforest are cut down, leading to a situation in which the inability to sustainably manage the soil results in the loss of places where people can live.<\/p>\n Since establishing the Soil Conservation Service (renamed the Natural Resources Conservation Service in 1994) in 1935, the U.S. Department of Agriculture has rolled out a variety of measures. China, too, has stressed the importance of black soil from the perspective of ensuring food safety, dubbing it the “giant panda of cultivated land,” and enacted the Black Soil Protection Law in 2022. Across the globe, people are recognizing that the question of how to maintain fertile black soil is an issue of virtually equal importance for a nation to that of how to protect its territory.<\/p>\n In Japan’s case, although our country is deemed to have a low food self-sufficiency rate, we at least have ample rice production capacity.<\/p>\n As Japan has a temperate climate with high rainfall, the progressive weathering of rock creates an abundance of clay-rich soil. It is a favorable environment on a global scale. Thanks to this soil, Japan has had a ceramic culture since ancient times. The Jomon period (c. 12,000–2,300 BCE) saw a culture of boiling food begin to develop, with people boiling acorns to remove the tannins before eating them, as well as using fish to create hot pot dishes. This has also influenced Japanese people’s preference for soft foods.<\/p>\n In addition, our mountainous country with few plains has a long tradition of cultivating rice on its very limited supply of flat ground. What has made this possible is the supply of nutrient-rich water flowing down from the mountains and channeled through a network of irrigation and drainage canals with a total length of 400,000 km—about the same as the distance from Earth to the Moon. We take for granted the sight of drooping ears of rice in autumn, but it is only thanks to an environment blessed with fertile soil and abundant water that we can enjoy it.<\/p>\n Japan’s agriculture is said to be at an overwhelming disadvantage compared with other countries in terms of costs and scale, but its strength is sustainability. Whereas the history of rice production in California dates back only 100 years or so, rice cultivation in Japan has been going on for thousands of years. While Japan has only a small area of agricultural land, with many mountains and rivers, rain and snow falling on the mountains supply nutrients to the soil every year.<\/p>\n As mentioned above, both dairy farming and fast food in Japan can place a burden on the soil in other parts of the world. To put it another way, increasing sustainable agriculture in Japan will increase our food supply without imposing a burden on other countries’ soil. Innovation will be required to enable us to sustain such agricultural methods, and we should each consider where and in what soil our food is produced.<\/p>\n Soil is a complex structure composed not only of minerals released by the weathering of rocks on Earth’s surface, but also of water, air, organic and inorganic matter, and microorganisms. Formed over long periods of time under the influence of climate, topography, and living organisms, among others, soil is a living system that governs ecosystems, supports biological activity, and plays an essential role in our lives as a place where food is produced. However, it has deteriorated significantly as human activity has intensified, and is also affected by climate change. People are now becoming aware of a crucial question: how can we maintain Earth’s soil?<\/p>\n","protected":false},"author":2,"featured_media":2636,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[18],"tags":[107],"class_list":["post-2640","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-nature","tag-agriculture"],"acf":{"author":"composition by Rie Iizuka","intro":" Soil is a complex structure composed not only of minerals released by the weathering of rocks on Earth’s surface, but also of water, air, organic and inorganic matter, and microorganisms. Formed over long periods of time under the influence of climate, topography, and living organisms, among others, soil is a living system that governs ecosystems, supports biological activity, and plays an essential role in our lives as a place where food is produced. However, it has deteriorated significantly as human activity has intensified, and is also affected by climate change. People are now becoming aware of a crucial question: how can we maintain Earth’s soil?<\/p>","person":[{"acf_fc_layout":"personcontent","personimg":2635,"personsholder":"Unit Leader, Soil Homeostasis Research Unit, Fukushima Institute for Research, Education and Innovation (F-REI)","personname":"Kazumichi Fujii","persondetail":"Soil scientist. Born in 1981 in Toyama Prefecture. After successfully completing a doctoral program at Kyoto University’s Graduate School of Agriculture, he received a Ph.D. in Agriculture. After holding positions including Senior Researcher at the Forest Research and Management Organization’s Forestry and Forest Products Research Institute, he took up his current post in March 2025. With his trusty trowel in hand, he travels throughout Japan and across the globe to conduct research ranging from the permafrost of the Canadian Arctic to the tropical rainforests of Indonesia. His book Tsuchi: Chikyū saigo no nazo<\/i> [Soil: Earth’s last mystery] (Kobunsha Shinsho) was awarded the seventh Kawai Hayao Prize for social sciences and humanities, while Tsuchi to seimei no 46 oku nen shi<\/i> [The 4.6-billion-year history of soil and life] (Kodansha) received the 41st Kodansha Science Publication Award. His other books include Daichi no 5 oku nen<\/i> [500 million years of earth] (Yama-kei Publishers). He has also made many appearances in the media."}],"issue":2638,"custom_css":""},"_links":{"self":[{"href":"https:\/\/healthist.net\/en\/wp-json\/wp\/v2\/posts\/2640","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/healthist.net\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/healthist.net\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/healthist.net\/en\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/healthist.net\/en\/wp-json\/wp\/v2\/comments?post=2640"}],"version-history":[{"count":0,"href":"https:\/\/healthist.net\/en\/wp-json\/wp\/v2\/posts\/2640\/revisions"}],"acf:post":[{"embeddable":true,"href":"https:\/\/healthist.net\/en\/wp-json\/wp\/v2\/issue\/2638"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/healthist.net\/en\/wp-json\/wp\/v2\/media\/2636"}],"wp:attachment":[{"href":"https:\/\/healthist.net\/en\/wp-json\/wp\/v2\/media?parent=2640"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/healthist.net\/en\/wp-json\/wp\/v2\/categories?post=2640"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/healthist.net\/en\/wp-json\/wp\/v2\/tags?post=2640"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}![\"\"](\"https:\/\/healthist.net\/en\/wp-content\/uploads\/sites\/3\/2026\/03\/296_en_feature01_01_fig02.jpg\")
<\/small><\/p>\nArtificial soil: still beyond our reach<\/h2>\n
![\"\"](\"https:\/\/healthist.net\/en\/wp-content\/uploads\/sites\/3\/2026\/03\/296_en_feature01_01_fig03-1.png\")
<\/small><\/p>\n![\"\"](\"https:\/\/healthist.net\/en\/wp-content\/uploads\/sites\/3\/2026\/03\/296_en_feature01_01_fig04.jpg\")
<\/small><\/p>\nJapan is reliant on overseas soil<\/h2>\n
Desertification progresses unnoticed<\/h2>\n