In our time, the cultivation of vegetable and fruit crops without mineral fertilizers is hard to imagine. After all, they all have a positive effect on plants, without which it is difficult to imagine their normal growth. Even ardent opponents of mineral fertilizers admit that they have an optimal effect on seedlings and do not harm the soil.

Of course, if mineral fertilizers are poured onto a small area with big big-bags, there can be no talk about their benefits, but if you follow all the rules and technologies, then everything will work out. In this article you will learn about the effect of certain mineral compounds on plants, because each of them will be used in different cases.

Let's start with the effect of nitrogen fertilizers on plants. Firstly, nitrogen is one of the main elements that affect seedling growth. They are advised to use, applying directly to the soil during spring plowing in the form of urea (urea) or ammonia acid. Note that nitrogen fertilizers are transported in large quantities in special big bags.

When do you need to use nitrogen fertilizers?

They are used when there is a lack of nitrogen in plants. Determining the lack of nitrogen is very simple. The leaves of the plants turn yellow or pale green.

  The main advantages of nitrogen fertilizers:

1) They can be operated on different soils;

2) They fertilizers create conditions for the rapid growth of plants;

3) These fertilizers improve the quality of the fruit.

Now we will talk about the effect of potassium compounds on seedlings. Potassium is an element that affects yield, resistance to drought and resistance to low temperatures. Finding out that a plant lacks potassium is just as easy as finding out that a plant lacks nitrogen. A sign that the plant lacks potassium, are white borders on the edge of the leaf, low elasticity of the leaf. When using potash fertilizers, plants quickly come to life and grow.

When using potassium salts, you need to remember the rules and technologies for their application and avoid abuse, because mineral fertilizers should be applied only when necessary. Also, do not forget that the soil should be given rest.

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Different nutrients, getting into the soil with fertilizers, undergo significant transformations. At the same time, they have a significant effect on soil fertility.

And soil properties, in turn, can have both positive and negative effects on fertilizers. This relationship between fertilizers and soil is very complex and requires deep and thorough research. Various sources of losses are associated with the conversion of fertilizers in the soil. This problem is one of the main tasks of agrochemical science. R. Kundler et al. (1970) in general terms show the following possible transformations of various chemical compounds and the associated loss of nutrients by leaching, volatilization in gaseous form and fixing in soil.

It is quite clear that these are just some indicators of the conversion of various forms of fertilizers and nutrients in the soil, they still do not cover the many ways of converting various mineral fertilizers depending on the type and properties of the soil.

Since the soil is an important part of the biosphere, it is primarily subjected to complex complex effects of fertilizers, which can have the following effects on the soil: cause acidification or alkalization of the environment; improve or worsen the agrochemical and physical properties of the soil; promote exchange absorption of ions or displace them in soil solution; promote or inhibit the chemical absorption of cations (biogenic and toxic elements); contribute to the mineralization or synthesis of soil humus; enhance or weaken the effect of other nutrients in the soil or fertilizers; mobilize or immobilize the nutrients of the soil; cause antagonism or synergism of nutrients and, therefore, significantly affect their absorption and metabolism in plants.

In the soil, there can be a complex direct or indirect interaction between biogenic toxic elements, macro - and microelements, and this has a significant effect on soil properties, plant growth, their productivity and crop quality.

Thus, the systematic use of physiologically acidic mineral fertilizers on acidic soddy-podzolic soils increases their acidity and accelerates the washing out of the arable layer of calcium and magnesium and, consequently, increases the degree of unsaturation with bases, reducing soil fertility. Therefore, on such unsaturated soils, the use of physiologically acidic fertilizers must be combined with liming and neutralizing the applied mineral fertilizers.

The twenty-year use of fertilizers in Bavaria on silty, poorly drained soil in combination with liming under grasses led to an increase in pH from 4.0 to 6.7. In the absorbed soil complex, exchange aluminum was replaced by calcium, which led to a significant improvement in soil properties. Loss of calcium as a result of leaching was 60-95% (0.8-3.8 kg / ha per year). As calculations showed, the annual need for calcium was 1.8-4 kg / ha. In these experiments, the yield of agricultural plants correlated well with the degree of saturation of the soil with bases. The authors concluded that to obtain a high yield, soil pH\u003e 5.5 and a high degree of saturation with bases (V \u003d 100%) are required; in this case, exchange aluminum is removed from the zone of the largest distribution of the plant root system.

In France, the great importance of calcium and magnesium in increasing soil fertility and improving their properties. It was found that leaching leads to depletion of calcium and magnesium

in the soil. On average, the annual loss of calcium is 300 kg / ha (200 kg on acidic soil and 600 kg on carbonate), and magnesium - 30 kg / ha (on sandy soils they reached 100 kg / ha). In addition, some crop rotation crops (legumes, industrial crops, etc.) carry significant amounts of calcium and magnesium from the soil, which is why crops following them often reveal symptoms of deficiency of these elements. We must not forget that calcium and magnesium play the role of physico-chemical ameliorants, having a beneficial effect on the physical and chemical properties of the soil, as well as on its microbiological activity. This indirectly affects the conditions of mineral nutrition of plants with other macro - and microelements. To maintain soil fertility, it is necessary to restore the level of calcium and magnesium lost as a result of leaching and removal of agricultural crops from the soil; for this, 300-350 kg of CaO and 50-60 kg of MgO per 1 ha should be added annually.

The task is not only to make up for the loss of these elements due to leaching and removal by agricultural crops, but also to restore soil fertility. In this case, the application rates of calcium and magnesium depend on the initial pH value, the content of MgO in the soil and the fixing ability of the soil, i.e., primarily on the content of physical clay and organic matter in it. It is estimated that to increase the soil pH by one unit, lime should be added from 1.5 to 5 t / ha, depending on the content of physical clay (<10% - >30%). In order to increase the magnesium content in the arable soil layer by 0.05%, 200 kg of MgO / ha should be added.

It is very important to establish the correct dose of lime in the specific conditions of its use. This question is not as simple as it is often presented. Typically, the dose of lime is set depending on the degree of acidity of the soil and its saturation with bases, as well as the variety of soil. These issues require further, deeper study in each case. The important question is the frequency of lime application, the fractionation of application in crop rotation, the combination of liming with phosphorization and the introduction of other fertilizers. The need for advanced liming has been established as a condition for increasing the efficiency of mineral fertilizers on acidic soils of the taiga-forest and forest-steppe zones. Liming significantly affects the mobility of macro - and microelements of fertilizers and soil itself. And this affects the productivity of agricultural plants, the quality of food and feed, and therefore on human and animal health.

M.R.Sheriff (1979) believes that possible re-reporting of soils can be judged by two levels: 1) when the productivity of pastures and animals does not increase with additional application of lime (this is what the author calls the maximum economic level) and 2) when liming violates the nutritional balance substances in the soil, and this adversely affects plant productivity and animal health. The first level in most soils is observed at a pH of about 6.2. On peat soils, the maximum economic level is observed at pH 5.5. Some pastures on light volcanic soils do not show any signs of responsiveness to lime at their natural pH of 5.6.

It is necessary to strictly consider the requirements of cultivated crops. So, the tea bush prefers acid red soils and yellow-podzolic soils, liming depresses this culture. The introduction of lime adversely affects flax, potatoes (details) and other plants. Legumes that are inhibited on acidic soils respond best to lime.

The problem of plant productivity and animal health (second level) most often occurs at pH \u003d 7 or more. In addition, soils vary in speed and degree of responsiveness to lime. For example, according to M. R. Sheriff (1979), to change the pH from 5 to 6 for light soils, it takes about 5 t / ha, and for heavy clay soil 2 times more. It is also important to consider the content of calcium carbonate in the calcareous material, as well as the friability of the rock, the fineness of its grinding, etc. From an agrochemical point of view, it is very important to take into account the mobilization and immobilization of macro - and microelements in the soil under the influence of liming. It has been established that lime mobilizes molybdenum, which in excessive amounts can adversely affect plant growth and animal health, but at the same time there are symptoms of copper deficiency in plants and livestock.

The use of fertilizers can not only mobilize individual nutrients in the soil, but also bind them, turning them into a form inaccessible to plants. Studies conducted in our country and abroad show that the unilateral use of high doses of phosphorus fertilizers often significantly reduces the content of mobile zinc in the soil, causing zinc starvation of plants, which negatively affects the quantity and quality of the crop. Therefore, the use of high doses of phosphate fertilizers often necessitates the introduction of zinc fertilizers. Moreover, the application of one phosphorus or zinc fertilizer may not have an effect, and their combined use will lead to a significant positive interaction.

There are many examples that testify to the positive and negative interaction of macro- and microelements. At the All-Union Scientific Research Institute of Agricultural Radiology, the effect of mineral fertilizers and soil liming with dolomite on the intake of strontium radionuclide (90 Sr) in plants was studied. The content of 90 Sr in the crop of rye, wheat and potatoes under the influence of complete mineral fertilizer decreased by 1.5-2 times compared with unfertilized soil. The lowest content of 90 Sr in the wheat crop was in the variants with high doses of phosphorus and potassium fertilizers (N 100 P 240 K 240), and in potato tubers when high doses of potassium fertilizers were applied (N 100 P 80 K 240). The introduction of dolomite reduced the accumulation of 90 Sr in the wheat crop by 3–3.2 times. The introduction of a complete fertilizer N 100 P 80 K 80 against the background of liming with dolomite reduced the accumulation of radio strontium in grain and wheat straw by 4.4–5 times, and at a dose of N 100 P 240 K 240 by 8 times compared to the content without liming.

F.A. Tikhomirov (1980) points to four factors affecting the size of the removal of radionuclides from soils by crop plants: the biogeochemical properties of technogenic radionuclides, soil properties, biological characteristics of plants and agrometeorological conditions. For example, from the arable layer of typical soils of the European part of the USSR, 1–5% of 90 Sr contained in it and up to 1% of 137 Cs are removed as a result of migration processes; on light soils, the rate of removal of radionuclides from the upper horizons is significantly higher than on heavy soils. The better supply of plants with nutrients and their optimal ratio reduce the intake of radionuclides in plants. Cultures with deeply penetrating root systems (alfalfa) accumulate less radionuclides than with surface root systems (ryegrass).

On the basis of experimental data, a system of agricultural measures was scientifically substantiated in the radioecology laboratory of Moscow State University, the implementation of which significantly reduces the intake of radionuclides (strontium, cesium, etc.) in crop production. These measures include: dilution of radionuclides entering the soil in the form of practically weightless impurities with their chemical analogues (calcium, potassium, etc.); reducing the degree of availability of radionuclides in the soil by introducing substances that convert them into less accessible forms (organic matter, phosphates, carbonates, clay minerals); incorporation of the contaminated soil layer into the subsurface horizon beyond the zone of distribution of root systems (to a depth of 50-70 cm); selection of crops and varieties that accumulate the minimum amount of radionuclides; placement of industrial crops on contaminated soils, use of these soils for seed plots.

These measures can be used to reduce pollution of agricultural products and toxic substances of non-radioactive nature.

The studies of E.V. Yudintseva et al. (1980) also found that calcareous materials reduce the accumulation of 90 Sr from sod-podzolic sandy loam soil in barley grain by about 3 times. The introduction of increased doses of phosphorus against the background of blast furnace slag reduced the content of 90 Sr in barley straw by 5-7 times, in grain by 4 times.

Under the influence of calcareous materials, the content of cesium (137 Cs) in the barley crop decreased by 2.3–2.5 times compared to the control. When high doses of potassium fertilizers and blast furnace slags were combined, the content of 137 Cs in straw and grain decreased by 5–7 times compared to the control. The effect of lime and slag on reducing the accumulation of radionuclides in plants is more pronounced on sod-podzolic soil than on gray forest soil.

Studies by U.S. scientists found that when using Ca (OH) 2 for liming, the toxicity of cadmium was reduced as a result of the binding of its ions, while the use for liming CaCO 3 was ineffective.

In Australia, the effect of manganese dioxide (MnO 2) on the absorption of lead, cobalt, copper, zinc and nickel by clover plants was studied. It was established that when manganese dioxide was added to the soil, the absorption of lead and cobalt and to a lesser extent nickel decreased more strongly; the absorption of copper and zinc by MnO 2 had a negligible effect.

In the USA, studies have also been conducted on the effect of various levels of lead and cadmium in the soil on the absorption of calcium, magnesium, potassium and phosphorus by corn, as well as on the dry weight of plants.

It can be seen from the table that cadmium had a negative effect on the intake of all elements in 24-day-old corn plants, and lead slowed the intake of magnesium, potassium, and phosphorus. Cadmium also negatively affected the intake of all elements in 31-day-old corn plants, and lead had a positive effect on the concentration of calcium and potassium and a negative effect on the magnesium content.

These issues are of great theoretical and practical importance, especially for agriculture in industrially developed regions, where the accumulation of a number of trace elements, including heavy metals, is increasing. At the same time, there is a need for a deeper study of the mechanism of interaction of various elements on their entry into the plant, on crop formation and product quality.

The University of Illinois (USA) also studied the effect of the interaction of lead and cadmium on their absorption by corn plants.

In plants, there is a definite tendency to increase the absorption of cadmium in the presence of lead; Soil cadmium, in contrast, reduced lead absorption in the presence of cadmium. Both metals in the tested concentrations inhibited the vegetative growth of corn.

Of interest are studies carried out in Germany on the effect of chromium, nickel, copper, zinc, cadmium, mercury and lead on the absorption of phosphorus and potassium by spring barley and the movement of these nutrients in plants. In the studies, labeled 32 P and 42 K atoms were used. Heavy metals were added to the nutrient solution at a concentration of 10 -6 to 10 -4 mol / L. A significant influx of heavy metals into the plant was established with an increase in their concentration in the nutrient solution. All metals exerted (to a different extent) an inhibitory effect both on the supply of phosphorus and potassium to plants and on their movement in the plant. The inhibitory effect on potassium intake was manifested to a greater extent than phosphorus. In addition, the movement of both nutrients into the stems was suppressed more than the entry into the roots. The comparative effect of metals on the plant occurs in the following descending order: mercury → lead → copper → cobalt → chromium → nickel → zinc. This order corresponds to the electrochemical series of element voltages. If the action of mercury in the solution was clearly manifested even at a concentration of 4 ∙ 10 -7 mol / L (\u003d 0.08 mg / L), then the effect of zinc - only at a concentration above 10 -4 mol / L (\u003d 6.5 mg / L )

As already noted, in industrialized areas, the accumulation of various elements in the soil, including heavy metals. Near major highways in Europe and North America, the effects of lead compounds on plants and air with exhaust gases are very noticeable. Some lead compounds enter the plant tissue through the leaves. Numerous studies have found an increased lead content in plants and soil at a distance of up to 50 m away from the freeways. There have been cases of poisoning of plants in places of particularly intense exposure to exhaust gases, for example, fir trees up to 8 km from a major Munich airport, where about 230 sorties per day are carried out. The spruce needles contained 8-10 times more lead than the needles in unpolluted areas.

Compounds of other metals (copper, zinc, cobalt, nickel, cadmium, etc.) noticeably affect plants near metallurgical enterprises, coming both from air and from the soil through the roots. In such cases, it is especially important to study and implement techniques that prevent excessive intake of toxic elements in plants. So, in Finland, the content of lead, cadmium, mercury, copper, zinc, manganese, vanadium and arsenic in the soil, as well as lettuce, spinach and carrots grown near industrial facilities and motorways and in clean areas were determined. Wild berries, mushrooms and meadow herbs were also investigated. It was found that in the zone of operation of industrial enterprises the lead content in lettuce ranged from 5.5 to 199 mg / kg dry weight (background 0.15-3.58 mg / kg), in spinach - from 3.6 to 52.6 mg / kg dry weight (background 0.75-2.19), in carrots - 0.25-0.65 mg / kg. The lead content in the soil was 187-1000 mg / kg (background 2.5-8.9). The lead content in mushrooms reached 150 mg / kg. With the distance from the freeways, the lead content in plants decreased, for example, in carrots from 0.39 mg / kg at a distance of 5 m to 0.15 mg / kg at a distance of 150 m. The cadmium content in the soil varied within 0.01-0 , 69 mg / kg, zinc - 8.4-1301 mg / kg (background concentrations, respectively, were 0.01-0.05 and 21.3-40.2 mg / kg). It is interesting to note that liming of contaminated soil reduced the cadmium content in lettuce from 0.42 to 0.08 mg / kg; potash and magnesium fertilizers did not have a noticeable effect on him.

In areas of severe pollution, the zinc content in the herbs was high - 23.7-212 mg / kg dry weight; the arsenic content in the soil is 0.47-10.8 mg / kg, in lettuce - 0.11-2.68, spinach - 0.95-1.74, carrots - 0.09-2.9, forest berries - 0 , 15-0.61, mushrooms - 0.20-0.95 mg / kg dry matter. The mercury content in cultivated soils was 0.03-0.86 mg / kg, in forest soils - 0.04-0.09 mg / kg. Noticeable differences in mercury content in different vegetables were not found.

The effect of liming and flooding of the fields on a decrease in the supply of cadmium to plants is noted. For example, the cadmium content in the topsoil of rice fields in Japan is 0.45 mg / kg, and its content in rice, wheat and barley on uncontaminated soil is 0.06 mg / kg, 0.05 and 0.05 mg / kg, respectively . The most sensitive to cadmium is soy, in which a decrease in growth and mass of grains occurs when the content of cadmium in the soil is 10 mg / kg. The accumulation of cadmium in rice plants in an amount of 10-20 mg / kg causes a suppression of their growth. In Japan, the maximum permissible concentration of cadmium in rice grains is 1 mg / kg.

In India, there is a problem of copper toxicity due to its large accumulation in soils located near the copper mines in Bihar. Toxic levels of EDTA-Cu citrate\u003e 50 mg / kg soil. Indian scientists have also studied the effect of liming on the copper content in drainage water. Norms of lime were 0.5, 1 and 3 of the required for liming. Studies have shown that liming does not solve the problem of copper toxicity, since 50-80% of the precipitated copper remained in a form accessible to plants. The content of available copper in the soil depended on the rate of liming, the initial copper content in the drainage water, and soil properties.

Studies have shown that typical symptoms of zinc deficiency were observed in plants grown in a culture medium containing this element 0.005 mg / kg. This led to inhibition of plant growth. At the same time, zinc deficiency in plants contributed to a significant increase in the adsorption and transport of cadmium. With an increase in the concentration of zinc in the nutrient medium, the supply of cadmium to plants sharply decreased.

Of great interest is the study of the interaction of individual macro - and microelements in the soil and in the process of plant nutrition. So, in Italy, the effect of nickel on the intake of phosphorus (32 P) in nucleic acids of young corn leaves was studied. The experiments showed that a low concentration of nickel stimulated, and a high one suppressed the growth and development of plants. In the leaves of plants grown at a nickel concentration of 1 μg / L, the supply of 32 P to all fractions of nucleic acids was more intense than in the control. At a nickel concentration of 10 μg / L, the uptake of 32 P into nucleic acids decreased markedly.

From numerous research data, it can be concluded that in order to prevent the negative effect of fertilizers on the fertility and soil properties, a scientifically based fertilizer system should include the prevention or mitigation of possible negative phenomena: acidification or alkalization of the soil, deterioration of its agrochemical properties, non-exchange absorption of nutrients, chemical absorption of cations excessive mineralization of humus soil, mobilization of an increased number of elements, leading to toxic de Corollary and t. d.

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If you read the articles that I posted in previous posts, you now understand how the symbiosis of worms, plants, and soil microflora works.

So to summarize.
  Plants with their fruits and their humus (leaves, stems, roots, etc.) attract the microflora of the soil to their roots. The plant itself cannot directly take all the necessary substances from the soil. They invite bacteria and fungi, which with the help of their enzymes digest all organics, making the so-called broth, which they "eat" themselves and which "eat" the plants. Then part of the bacteria, which multiply greatly during nutrition, are eaten by earthworms. Digesting bacteria and the remnants of the broth, the worms "produce" the actual humus. And humus is a repository of a whole complex of substances that make the soil fertile. Humus, as it were, accumulates these substances, preventing them from being washed out of the soil by water and other natural factors and leading to soil degradation and erosion.

Thus, it becomes clear that if you somehow influence the process of creating humus, the process of plant nutrition, this unique symbiosis of microflora, worms and plants, you can disrupt the process of humus production and the process of normal plant nutrition.

This is what modern traditional agriculture does. It brings tons of chemicals into the earth, upsetting the harmonious balance of microflora.

Now it is clear that soil fertility depends on the health of soil microflora.
  But herbicides and pesticides kill this microflora. Kill completely. As proof of this, our farmer friend - he says that where he doesn’t put mineral fertilizers, he doesn’t have potatoes there at all - the bushes grow to a height of 10 cm and that’s all, tubers don’t want to be tied at all. And he believes that there is only one way out - to put more mineral fertilizers. And every year more and more ....

Mineral fertilizer plants are drug addicts. These plants "sit on doping," on drugs. Everything would be fine, but only plants cannot directly digest these fertilizers, they still need microflora. But this microflora is destroyed more and more every year by chemicals and mineral fertilizers themselves. Here is a quote from a gardening site: " mineral fertilizers change the qualitative composition of soil microorganisms, destroy molecules of humic acids, impair fertility, or completely disrupt fertility, because soil structure is violated, often, which seemed like lifeless dust, soils are simply taken out of use "(http://www.7dach.ru/VeraTyukaeva/unikalnye-guminovye-kisloty-21195.html )

And here's another article about the effect of mineral fertilizers on soil and humans: (based on materials from the site http://sadisibiri.ru/mineralnie-udobrebiya-vred-polza.html)

Mineral fertilizers: benefits and harms

Yes, the crop from them is growing,

But nature is ruining.

Nitrates eat people

More and more from year to year.

World production of mineral fertilizers is growing rapidly. Every decade, it increases by about 2 times. The yield of crops from their application, of course, is growing, but this problem has many negative aspects, and this worries a lot of people. It is not for nothing that in some Western countries the government supports vegetable growers who grow products without the use of mineral fertilizers - environmentally friendly.

MIGRATION OF NITROGEN AND PHOSPHORUS FROM SOIL

It is proved that from the nitrogen introduced into the soil, plants absorb about 40%, the rest of the nitrogen is washed out of the soil by rain and evaporates in the form of gas. To a lesser extent, but phosphorus is washed out of the soil. The accumulation of nitrogen and phosphorus in groundwater leads to pollution of water bodies, they quickly age and turn into swamps, because the increased content of fertilizers in the water entails the rapid growth of vegetation. Dying plankton and algae are deposited on the bottom of water bodies, this leads to the release of methane, hydrogen sulfide and to a decrease in the supply of water-soluble oxygen, which causes fish to freeze. The species composition of valuable fish is also declining. The fish did not begin to grow to normal size, it began to age earlier, to die earlier. Plankton in reservoirs accumulates nitrates, fish feed on them, and eating such fish can lead to stomach diseases. And the accumulation of nitrogen in the atmosphere leads to acid rain, acidifying the soil and water, destroying building materials, oxidizing metals. Forests and the animals and birds living in them suffer from all this, and fish and mollusks die in water bodies. There is a report that on some plantations where mussels are harvested (these are edible mollusks, they used to be very appreciated), they became inedible, moreover, there were cases of poisoning by them.

INFLUENCE OF MINERAL FERTILIZERS ON SOIL PROPERTIES

Observations show that the humus content in soils is constantly decreasing. Fertile soils, chernozems at the beginning of the century contained up to 8% humus. Now there are almost no such soils. Podzolic and sod-podzolic soils contain 0.5-3% humus, gray forest soils - 2-6%, meadow chernozems - more than 6%. Humus serves as a repository of the basic elements of plant nutrition; this is a colloidal substance, particles of which hold nutrients on their surface in a form accessible to plants. Humus is formed when microorganisms decompose residues of plant origin. Humus cannot be replaced with any mineral fertilizers, on the contrary, they lead to the active mineralization of humus, the soil structure deteriorates, from colloidal lumps holding water, air, nutrients, the soil turns into a dusty substance. From natural soil to artificial. Mineral fertilizers provoke leaching of calcium, magnesium, zinc, copper, manganese, etc. from the soil, this affects the processes of photosynthesis, reduces the resistance of plants to diseases. The use of mineral fertilizers leads to soil compaction, a decrease in its porosity, and a decrease in the proportion of granular aggregates. In addition, the acidification of the soil, which inevitably occurs when applying mineral fertilizers, requires an increasing amount of lime. In 1986, 45.5 million tons of lime was added to the soil in our country, but this did not compensate for the loss of calcium and magnesium.

SOIL POLLUTION BY HEAVY METALS AND TOXIC ELEMENTS

The raw materials used for the production of mineral fertilizers contain strontium, uranium, zinc, lead, cadmium, etc., which are technologically difficult to extract. As impurities, these elements enter superphosphates and potash fertilizers. Heavy metals are the most dangerous: mercury, lead, cadmium. The latter destroys red blood cells in the blood, disrupts the kidneys, intestines, softens the tissues. A healthy person weighing 70 kg without harm to health can receive up to 3.5 mg of lead, 0.6 mg of cadmium, 0.35 mg of mercury per week with food. However, on highly fertilized soils, plants can also accumulate large concentrations of these metals. For example, in cow's milk there can be up to 17-30 mg of cadmium in 1 liter. The presence of uranium, radium, and thorium in phosphate fertilizers increases the level of internal exposure of humans and animals when plant food enters their body. The composition of superphosphate also includes fluorine in an amount of 1-5%, and its concentration can reach 77.5 mg / kg, causing various diseases.

MINERAL FERTILIZERS AND SOIL LIVING WORLD

The use of mineral fertilizers causes a change in the species composition of soil microorganisms. The number of bacteria capable of assimilating the mineral forms of nitrogen increases significantly, but the number of symbiont micro fungi in the rhizosphere of plants decreases (the rhizosphere is a 2-3-mm region of soil adjacent to the root system). The number of nitrogen-fixing bacteria in the soil is also decreasing - they seem to be no longer needed. As a result, the root system of plants reduces the release of organic compounds, and their volume was about half the mass of the aboveground part, and plant photosynthesis is reduced. Toxin-forming micro fungi are activated, the number of which under natural conditions is controlled by beneficial microorganisms. The application of lime does not save the situation, but sometimes leads to an increase in soil contamination by root rot pathogens.

Mineral fertilizers cause severe depression of soil animals: foottails, roundworms and phytophages (they feed on plants), as well as a decrease in the enzymatic activity of the soil. And it is formed by the activity of all soil plants and living creatures of the soil, while the enzymes get into the soil as a result of their release by living organisms that die off microorganisms. It has been established that the use of mineral fertilizers reduces the activity of soil enzymes by more than two times.

HUMAN HEALTH PROBLEMS

In the human body, nitrates that are ingested are absorbed into the digestive tract, into the bloodstream, and with it into the tissues. About 65% of nitrates are converted to nitrites already in the oral cavity. Nitrites oxidize hemoglobin to metahemoglobin, which has a dark brown color; he is not able to carry oxygen. The norm of methemoglobin in the body is 2%, and a larger amount of it causes various diseases. With 40% methemoglobin in the blood, a person can die. In children, the enzymatic system is poorly developed, and therefore nitrates are more dangerous for them. Nitrates and nitrites in the body turn into nitroso compounds, which are carcinogens. In experiments on 22 animal species, it was proved that these nitroso compounds cause the formation of tumors on all organs except bones. Nitrosoamines, having hepatotoxic properties, also cause liver disease, in particular hepatitis. Nitrites lead to chronic intoxication of the body, weaken the immune system, reduce mental and physical performance, exhibit mutagenic and embrinotoxic properties.

For vegetables, the maximum standards for nitrates in mg / kg are established. These standards are constantly being adjusted upward. The level of the maximum permissible concentration of nitrates, now accepted in Russia, and the optimum acidity of the soil for some vegetables are given in the table (see below).

The actual nitrate content in vegetables, as a rule, exceeds the norm. The maximum daily dose of nitrates, which does not adversely affect the human body, is 200-220 mg per 1 kg of body weight. As a rule, 150-300 mg, and sometimes up to 500 mg per 1 kg of body weight, actually enter the body. Increasing crop yields, mineral fertilizers affect their quality. In plants, the carbohydrate content decreases and the amount of crude protein increases. In potatoes, the starch content decreases, and in grain crops the amino acid composition changes, i.e. protein nutrition is reduced.

The use of mineral fertilizers in growing crops also affects the storage of products. A decrease in sugar and dry matter in beets and other vegetables leads to a deterioration in their shelf life. The flesh darkens more strongly in potatoes, while preserving vegetables, nitrates cause corrosion of the metal of the cans. It is known that more nitrates are found in leaf veins near salads, spinach, up to 90% of nitrates are concentrated in the core of carrots, up to 65% in the upper part of beets, their amount increases during storage of juice and vegetables at high temperature. Vegetables from the beds are better to harvest mature and in the afternoon - then they have less nitrates. Where do nitrates come from, and when did this problem arise? There have always been nitrates in products, just their quantity has been growing recently. The plant feeds, takes nitrogen from the soil, nitrogen accumulates in the tissues of the plant, this is a normal phenomenon. Another thing is when there is an excess of this nitrogen in the tissues. Nitrates alone are not dangerous. Some of them are excreted from the body, another part is converted into harmless and even useful compounds. And the excess part of nitrates turns into salts of nitrous acid - this is nitrites. They deprive red blood cells of the opportunity to supply oxygen to the cells of our body. As a result, the metabolism is disturbed, the central nervous system - the central nervous system suffers, the body's resistance to diseases decreases. Among vegetables, the champion in the accumulation of nitrates is beets. Less of them in cabbage, parsley, onions.

The influence of mineral fertilizers on product quality and human health

Mineral fertilizers can have a negative effect both on plants and on the quality of plant products, as well as on organisms that consume them. The main of these effects are presented in tables 1, 2.

At high doses of nitrogen fertilizers, the risk of plant disease increases. There is an excessive accumulation of green mass, and the likelihood of plant lodging sharply increases.

Many fertilizers, especially chlorine-containing (ammonium chloride, potassium chloride), adversely affect animals and humans, mainly through water, which releases the released chlorine.

The negative effect of phosphate fertilizers is associated mainly with the fluorine, heavy metals and radioactive elements contained in them. Fluorine with its concentration in water of more than 2 mg / l can contribute to the destruction of tooth enamel.

Table 1

The effect of mineral fertilizers on plants and the quality of plant products (according to various sources)

Types of fertilizers
	positive	negative
		At high doses or untimely application methods - accumulation in the form of nitrates (especially in vegetables), violent growth at the expense of stability, increased incidence, especially of fungal diseases. Ammonium chloride promotes the accumulation of chlorine. The main accumulators of nitrates are vegetables, corn, oats, and tobacco.
Phosphoric	Reduce the negative effects of nitrogen, improve product quality, help increase plant resistance to diseases	At high doses, plant toxicosis is possible. They act mainly through the heavy metals contained in them (cadmium, arsenic, selenium), radioactive elements and fluorine. The main stores are parsley, onion, sorrel.
Potash	Similar to phosphoric	Mainly through the accumulation of chlorine when making potassium chloride. With an excess of potassium - toxicosis. The main accumulators of potassium are potatoes, grapes, buckwheat, and vegetables.

table 2

The impact of mineral fertilizers on animals and humans (according to various sources)

Types of fertilizers	Main impacts
Nitric (nitrate forms)	Nitrates (MPC for water 10 mg / l, for food products - 500 mg / day per person) are restored in the body to nitrites, causing metabolic disorders, poisoning, deterioration of the immunological status, methemoglobinia (oxygen starvation of tissues). When interacting with amines (in the stomach) they form nitrosamines - the most dangerous carcinogens. In children, they can cause tachycardia, cyanosis, eyelash loss, rupture of the alveoli. In animal husbandry: vitamin deficiency, decreased productivity, the accumulation of urea in milk, increased morbidity, and decreased fertility.
Phosphoric (superphosphate and the fluorine, cadmium and other heavy metals contained in it)	Mostly through fluoride. An excess of it in drinking water (more than 2 mg / l) causes damage to tooth enamel in humans, loss of elasticity of blood vessels. With a content of more than 8 mg / l - osteochondrosis.
	Consumption of water with a chlorine content of more than 50 mg / l causes poisoning (toxicosis) in humans and animals.

Conclusion

The life of people depends on the soil and its fertility. The soil is considered a great laboratory, an arsenal that delivers the means of production, the subject of labor, a place for people to settle. Therefore, the soil must always be taken care of in order to fulfill its duty - to leave it improved for future generations.

Cultivated land is the result of complex natural processes and labor of many generations of people. Therefore, the quality of soils largely depends on the duration of cultivation of the land and the culture of agriculture. Together with the crop, a person removes a significant amount of mineral and organic substances from the soil, thereby combining it. So, with a potato crop of 136 kg / ha, the soil loses 48.4 kg of nitrogen, 19 kg of phosphorus and 86 kg of potassium. Therefore, it is necessary to systematically replenish the reserves of these elements in the soil by applying fertilizers. Applying the necessary crop rotation, carefully cultivating and fertilizing the soil, a person increases its fertility so significantly that most modern cultivated soils should be considered artificial, created with the participation of man.

Thus, in some cases, human exposure to soils leads to an increase in their fertility, in others to deterioration, degradation and death. Particularly dangerous consequences of human influence on soils include accelerated erosion, contamination with foreign chemicals, salinization, waterlogging, and removal of soils for various structures (highways, reservoirs, etc.). Damage to soils resulting from the irrational use of land has become threatening. The decrease in the area of \u200b\u200bfertile soils occurs many times faster than their formation. Especially dangerous for them is accelerating erosion.

Bibliography

1. Konstantinov V. M. Nature conservation. - M.: Publishing Center "Academy", 2000.

2. Voronkov N. A. Ecology general, social, applied. - M.: Agar, 2000.

3. Bokov V.A. et al. Geoecology. - Simferopol: Tavria, 1996.

4. Akimova T. A., Haskin V. V. Ecology. Man - Economy - Biota - Environment. - M.: UNITY-DANA, 2001

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