World of Agriculture 
Facts and Photos from every country of the world.

Soils: the “skin of our Earth"

Fast facts: soils

  • Soils consist of eroded stones and organic matter, which are decomposed by plants and together they nour-ish the plants.
  • Soils are the “skin of the earth”. Our plants for food and fodder grow in only 20 to 90 cm depths of soils.
  • Soils are full of life: 10 times more fauna biomass is underground than above ground.
  • Soil degradation is reducing soil fertility for plant growth and food production. 30% of farmland is degrad-ed.
  • Fertile natural soils are usually close to rivers and the sea. Sealing of best soils with buildings, roads and/or contamination is a loss for food production.


Human life depends on fertile soils, just 20 to 90 cm depth surface of our earth. In this “skin of the earth” grow the most of our useful plants and livestock (which are our source of food). Organic layer and topsoil (O and A horizon) are full of life, the edaphon (living organism) (Coleman et al. 2024). For example, in one liter of a typical topsoil in western Europa live tril-lions of bacteria, fungi, protozoa, nematodes, springtails, woodlice, arthropods, and earth-worms). To understand this: in just one hand full fertile soil live more organisms than humans on the earth. Naturally, they sum up to 1.5 to 2.5 kg dry matter of biomass per m3. Three quarter of the total biomass of these organisms are bacteria and fungi. They digest the dead biomass and produce the fertile soil as organic matter. Mycorrhiza and roots living in a symbiosis. The fungi deliver nutrients for the plants and the plants energy (glucoses) for the fungi.


Figure: Number of individuals per cubic meter in temperate European soils (logarithmically scaled)

Source: Bodenatlas (2024) (translated)


Figure: Soil map of the earth.

Source: FAO (2022b)

Photo 1: Laterite  soils can have a very red color. The cover about one third of the earth sur-face and found in the tropics and subtropics. They are considered as “heavy and old” soils, with high impact of tropical weathering (laterization) through leaching of rainwater in rainy season. They have a low pH (4.0-5.5), and aluminum and iron are fixed in the clay minerals. That makes the color “red”. Bricks made of clay have usually the color of laterite. Laterite soils are difficult to use for agriculture and called “minute soils”. They are suitable for crop cultivation with high cation and water holding capacities, if they can be managed.

If agriculture is practiced, the organic matter in natural soils is decreasing to 0.4 - 0.5 kg per m2, due to disturbance of the ecology of soil live and digestion of organic matter. Decreasing of soil fertility and decreasing of land altitude is the result. Fertilizing and construction of dikes are the options. Longterm agriculture like in Europe and Asia show, that the organic matter content is stable, on a lower level compared to the natural soils.

Photo 2: THE fertile soil Chernozem (means "black soil") contains a high percentage of or-ganic matter (humus: 4% to 16% in the dry matter) and a lot of phosphorus and ammonia. this soil is considered by the World Reference Base for Soil Resources  (WRB) as Reference Soil Group because of the high fertility. Ukraine is one of the countries with vast areas of such rich soils. That was the reason for Nazi-Germany to occupy the country in the World War II for the “Raum und Brot” and “Blut und Boden” policy and the country was the bread basket of the former Sovjet Union in the 20th century.

Table: The share of degrading area in each type of land cover by continental regions and world (unit: % of total area of a land cover type across a continental region).

Source: Le et al. (2014)

The opposite of farmland establishment is the soil degradation due to agriculture. This is a glob-al challenge (Filho et al. 2020). Some 30% of the world's agricultural land is seriously degraded (Le et al. 2014). About 12 million hectares of productive land is degraded every year (UNCCD 2004). Among the worst affected regions are Central America, where 75% of land is infertile, Africa, where a fifth of soil is degraded, and Asia, where 11% is unsuitable for agriculture (Figure, Table). About 3.2 billion people live in these degrading areas (Table 5). Most of the soil erosion is caused by water, either through flooding or poor irrigation, with the rest lost to winds (Doetterl et al. 2012). Agriculture practices such as ploughing also damage soil, as does repeated planting in fields, which depletes the soil of nutrients (Mateo-Zagasta et al. 2018).

Photo 3: A farmer in Norway creates farmland on 100 % stone land. The stones in the picture are the natural landscape of post glacial middle Norway. The forest and the grassland in the back are on recently made farmland. These manmade soils are much faster compared to soils made by nature (weathering), what can take millions of years.


Table: The number of people residing in degrading areas by region, the number in millions and the share in percentages.

Source: Le et al. (2014)


Figure: Global status of soil degradation
Source: UNEP (1997)

Photo 4: Erosion  is one of the main challenges in agriculture. Organic matter and nutrients are washed away. When forests or permanent grassland are cleared for arable farming, heavy rainfall can wash away the soil. What remains are bare stones and arable farming is no longer possible. In Ethiopia, a huge country, the land us has covered nearly all areas, where agriculture is possible. From 70% forest cover in the mid of last century, only 3% remained. Even step slopes are deforested and cultivated. Erosion is happening after heavy rains, which will occur more often with climate change. Today, the global erosion costs are calculated with 8 billion USD per year (Sartori et al. 2024). The EU has calculated  that water erosion could increase by 66% worldwide between 2015 and 2070 and cost up to USD 625 billion, which corresponds to 0.06% or 0.12% of global GDP.