State of world land resources and food security challenges

Global food production more than doubled between 1950 and 1984, and per capita food production increased by an average of 40%. During the same period, per capita food production declined in 43 developing countries (22 of which are African countries), where every seventh person on the planet lives. Growth in food production in most developing countries since 1950 has barely kept pace with their population growth.

Many of the world's poorest populations suffer simultaneously from both malnutrition and undernourishment. Each year, 20 to 40 million people die for this reason, half of whom are children under 5 years of age.

This is largely due to the unsatisfactory state of food energy sources, the main ones being:

• arable land, from which humans receive the main part of food energy — approximately 88%;
• natural pastures and forest lands provide about 10% of food energy;
• and finally, humans receive approximately 2% of food energy from water resources.

This entire life-support system is working at its limit, and its state is sometimes compared to metal under stress before breaking.

The world's land area is 129 million km2, or 86.5% of the land surface. Arable land and permanent crops account for about 15 million km2 (10% of land surface) of agricultural land, while hayfields and pastures cover 37.4 million km2 (25%). The remaining part of the land consists of low-productivity land and areas with a climate that is too cold.

The planet's land resources make it possible to provide food for more people than there are currently and will be in the near future. At the same time, due to population growth, especially in developing countries, the amount of arable land per capita is decreasing. Back in the early 80s, the per capita availability of arable land for the world's population was 0.45 — 0.5 hectares; currently, it is already 0.35 — 0.37 hectares.

The availability of arable land per person varies widely:

Every year, the world loses up to 6 — 7 million hectares of soil (0.06 — 0.07 million km). The land fund of Russia in 1992 amounted to 1709.6 million hectares. Over the last 27 years, the area of agricultural land in Russia has decreased by 12.4 million hectares, arable land by 2.3 million hectares, and hayfields by 10.6 million hectares.

These losses are practically irreversible, because destroyed soil is restored only over the course of several centuries, and even then only with a fortunate combination of many conditions. And the most productive, most important areas located in deltas, floodplains, and chernozem regions are the first to be lost. For example, the construction of hydroelectric power plants in the CIS flooded about 12 million hectares of agricultural land. In the Volga and Dnieper basins alone, 2.5 million hectares of fertile land were flooded.

The total area of land in Russia disturbed as a result of mineral extraction, construction, and geological exploration work amounted to 1.1 million hectares in 1991, of which 0.7 million hectares were disturbed between 1976 and 1991. More than 50% of this area was occupied by agricultural land.

The most common method of soil irrigation is sprinkling, which humidifies the air well and creates a favorable climate for plants. However, existing systems usually create high-intensity rain that the soil absorbs poorly. This leads to uneven irrigation, water erosion, disruption of groundwater levels, salinization, and waterlogging.

In the Russian Federation, 771 thousand hectares of irrigated land are in an unsatisfactory state, including 325 thousand hectares due to unacceptable groundwater levels, 292 thousand hectares due to salinization, and 154 thousand hectares due to the simultaneous presence of unacceptable groundwater levels and soil salinization. The areas of waterlogged and marshy land used as arable land in 1990 amounted to 8 million hectares (5.2% of arable land), whereas in 1985 there were 5.8 million hectares (4.5%).

Meanwhile, fundamentally new irrigation systems are known and already used in the world:

a) localized irrigation, where only the root-inhabited layers are moistened;

b) subsurface irrigation - water is supplied to the roots through pipes.

These methods eliminate evaporation losses, and if mineral fertilizers are added to the water, their efficiency is increased and environmental pollution is reduced .

Erosion, which is the process of soil displacement, mainly of its upper, most fertile horizons, takes away more than 3 million hectares of fertile land from humanity annually. The main factors of erosion are wind and surface water. From a bare, vegetation-free plot with a barely noticeable slope (at 2 degrees), water carries away 20 tons of soil per year.

The area of erosion-prone agricultural land in Russia totals 124 million hectares (56%), of which 87.3 million hectares is arable land. Soil productivity is declining over large areas due to a reduction in humus content. Over the last 20 years alone, humus reserves have decreased by 25–30%, and annual losses across the Russian Federation amount to 1.4 million tons. According to agrochemical surveys, 37.5 million hectares of arable land in Russia are characterized by low humus content.

Mechanical destruction and soil erosion: the role of machinery and tillage

Soil cover restoration is an extremely slow natural process: it takes from 200 to 1,000 years to form a layer just 2.54 cm (1 inch) thick in tropical and temperate latitudes. If erosion rates exceed the rate of soil formation, the soil loses its status as a renewable resource. Currently, on 1/3 of the world's cultivated lands, the arable layer is being destroyed faster than it can be restored. The annual volume of soil washed into water bodies and oceans is equivalent to a freight train capable of wrapping around the Earth 150 times.

In arid regions, the combination of harsh climatic conditions and human pressure leads to desertification. The drying out of topsoil horizons during droughts, accompanied by high temperatures and strong winds, is exacerbated by overgrazing, deforestation, and open-pit mining. According to field studies, up to 4.9 million hectares of land in arid zones are subject to desertification, of which 1.8 million hectares are in a state of severe degradation. On degraded pastures totaling 1.3 million hectares, about 250,000 hectares have already turned into shifting sands.

• Rate of 2.54 cm soil formation — 200–1,000 years
• Share of degrading arable land — 1/3 of global cropland
• Machine passes per season — up to 20 times
• Pressure of a wheeled tractor — 800 g/cm²

The physical condition of soil depends directly on the machinery used and the methods of tillage. Living organisms make up up to 1/10 of the total soil mass; however, the regular passage of heavy machinery (up to 20 times per season to obtain a harvest) destroys its structure. With an average tractor pressure of 800 g/cm², soil compaction occurs, leading to the death of soil biota. Only tracked vehicles have a relatively gentle impact on the soil profile. Additional damage is caused by fuel and lubricant leaks and exhaust gases absorbed by the ground.

Chemical imbalance and loss of productive land

In addition to physical destruction, the area of arable land is shrinking due to constant conversion for infrastructure and urban development. Building codes rigidly sequester productive land, and urban sprawl in developed countries destroys thousands of square kilometers of fertile territory every year.

The second fatal factor is chemical degradation due to a nutrient imbalance. Every year, more than 100 million tons of nitrogen alone are removed from soils with the harvest, as well as significant volumes of phosphorus, potassium, and magnesium. Industrial synthesis of nitrogen fertilizer can compensate for only one-fourth of this removal. The remaining nitrogen is fixed and converted into a form accessible to roots exclusively by soil microorganisms.

Intensification through mineral fertilizer has a low efficiency. Although 1 kg of fertilizer yields an increase of 5–6 kg of grain, and over the last 30 years total grain harvest has grown by a quarter, the volume of nitrogen application has jumped almost 8-fold during the same period. Solid fertilizers contain about 40% of the active ingredient, of which plants absorb no more than half. The unabsorbed residue is leached into groundwater and rivers.

Another pollutant consciously introduced by humans into the soil is pesticides. All types of pesticides are poisons and affect not only pests, weeds, and pathogens of crops, but also many other beneficial animals and plants.

In the USA, 61% of agricultural land is treated with pesticides (half the volume of pesticides used goes to the treatment of industrial crops only), in the CIS - 87%. It is estimated that 98% of insecticides (against insects) and fungicides (against fungal diseases), and 60 - 95% of herbicides (against weeds) do not reach the targets of suppression, but instead end up in water and air, accumulating in the soil and food products. In addition, zoocides (against rodents) are also used, which create a lifeless environment in the soil.

Pesticides containing chlorine, fluorine, and mercury possess extreme biological activity, high chemical activity, and the ability to accumulate in various links of the food chain. Even in negligible concentrations, they suppress the immune system of an organism and reduce a person's mental and physical performance. In higher concentrations, these substances have mutagenic, carcinogenic, and teratogenic (damaging to embryos) effects, affect the nervous system and the digestive tract, and disrupt women's reproductive functions.

Another problem is the increase in soil acidity. Factories, plants, and especially thermal power plants emit tens of millions of tons of sulfur and nitrogen oxides into the atmosphere annually, which travel hundreds of kilometers and fall to the ground as acid rain. These rains depress not only the soil and plants, but they also reduce the growth of tree species, decrease fish stocks, and affect human health. Most of the soil is deacidified in the suburban zone. On lands watered by acid rains, yields decrease by 40%.

Soils around large cities and major enterprises of non-ferrous and ferrous metallurgy, chemical and petrochemical industries, and machine building are contaminated with heavy metals, oil products, fluorine compounds, and other toxic substances at a distance of several tens of kilometers. In the soils of 85 cities of the Russian Federation, especially in the five-kilometer zone around them, the average lead content is in the range of 0.4 - 80 times the maximum permissible concentration.

The results of a study on the content of heavy metals in the soils of Tomsk and the Tomsk region are provided. For example, the soils of the Kirovsky district and the Irkutsk tract contain heavy metals of the 1st hazard class - cadmium, mercury, lead, zinc; the Leninsky district contains substances of the 2nd hazard class: cobalt, nickel, copper, chromium. A fairly high content of these metals was found in the soils of the Tomsky district, although the situation regarding soil contamination in Kemerovo is significantly better than in Tomsk, which is explained by the smaller number of harmful production facilities. The content of many elements in plants increases compared to their content in the soil, as plants absorb an additional amount of these elements from water and air.

After the accident at the Chernobyl NPP, zones of contamination with cesium-137 covering a total area of almost 55.1 thousand km2 were formed in 14 regions on the territory of Russia. In terms of impact on the environment, the accident at the Chernobyl NPP should be considered a minor nuclear war, which caused irreparable damage to land resources: hundreds of thousands of hectares of agricultural and forest land were practically put out of operation forever.

In the Sverdlovsk, Chelyabinsk, and Kurgan regions, an area of about 4000 km2 is contaminated with radioactive elements. The contamination is a consequence of the accidents in 1949, 1957, and 1967, as well as the production activities of the Mayak combine. Gamma radiation from radioactive elements, in particular from cesium-137, is about

60 µR/h, which is several times higher than the natural radioactive background.

Studies conducted at TPU made it possible to detect abnormal concentrations of certain radionuclides in soils even at a distance of about 80 km from the Siberian Chemical Combine. Similar anomalies appeared as a result of the normal production activities of the SCC, and the higher density of soil contamination in some settlements (villages of Georgievka and Naumovka) occurred as a result of the explosion at the SCC radiochemical plant on April 6, 1993.

Intensive soil contamination and the alienation of territories, including agricultural ones, occur as a result of radioactive waste disposal, especially if regulations are not followed during the process.

Thus, soil — an irreplaceable basis for food — is in need of protection and preservation.