http://biofile.ru/bio/4234.html

The increase in the mobility of some microelements contained in the soil should also be attributed to the negative consequences of the use of fertilizers. They are more actively involved in geochemical migration. This leads to a deficit of B, Zn, Cu, Mn in the arable layer. The limited supply of microelements to plants adversely affects the processes of photosynthesis and the movement of assimilates, reduces their resistance to diseases, insufficient and excessive moisture, high and low temperatures. The main cause of disturbances in the metabolism of plants with a lack of trace elements is a decrease in the activity of enzyme systems.

The lack of trace elements in the soil forces the use of microfertilizers. So, in the USA, their use in the period from 1969 to 1979. increased from 34.8 to 65.4 thousand tons of active ingredient.

Due to the profound changes in the agrochemical properties of soils resulting from the use of fertilizers, it became necessary to study their effect on physical characteristics arable layer. Main indicators physical properties soils are aggregate composition and water resistance of soil particles. Analysis of the results of a limited number of studies conducted to study the effect mineral fertilizers on the physical properties of the soil does not allow us to draw definite conclusions. In some experiments, a deterioration in physical properties was observed. When re-cropping potatoes, the proportion of soil aggregates larger than 1 mm in the variant with the introduction of nitrogen, phosphorus and potassium, compared with the unfertilized plot, decreased from 82 to 77%. In other studies, when a complete mineral fertilizer was applied for five years, the content of agronomically valuable aggregates in the chernozem decreased from 70 to 60%, and water-stable - from 49 to 36%.

Most often negative influence mineral fertilizers on the agrophysical properties of the soil is found when studying its microstructure.

Micromorphological studies have shown that even small doses of mineral fertilizers (30-45 kg/ha) have a negative effect on the soil microstructure, which persists for 1-2 years after their application. The packing density of microaggregates increases, the visible porosity decreases, and the proportion of granular aggregates decreases. Continuous application of mineral fertilizers leads to a decrease in the proportion of particles of spongy microstructure and to an increase of 11% in non-aggregated material. One of the reasons for the deterioration of the structure is the depletion of the arable layer with excrement of soil animals.

Probably, the agrochemical and agrophysical properties of soils are closely related, and therefore increasing acidity, depletion of the arable horizon in bases, a decrease in humus content, and deterioration in biological properties should naturally be accompanied by a deterioration in agrophysical properties.

In order to prevent the negative impact of mineral fertilizers on soil properties, liming should be carried out periodically. By 1966, the annual liming area in the former USSR exceeded 8 million hectares, and the volume of lime applied amounted to 45.5 million tons. However, this did not compensate for the loss of calcium and magnesium. Therefore, the proportion of lands subject to liming in a number of regions did not decrease, but even slightly increased. In order to prevent an increase in the area of ​​acidic lands, it was planned to double the supply of lime fertilizers to agriculture and bring them up to 100 million tons by 1990.

Liming, lowering the acidity of the soil, simultaneously causes an increase in gaseous losses of nitrogen. When carrying out this technique, they increase by 1.5-2 times. Such a reaction of soils to the introduction of ameliorants is the result of changes in the direction of microbiological processes, which can cause disruption of geochemical cycles. In this regard, doubts were expressed about the advisability of using liming. In addition, liming exacerbates another problem - soil pollution with toxic elements.

Mineral fertilizers are the main source of soil pollution with heavy metals (HM) and toxic elements. This is due to the content of strontium, uranium, zinc, lead, vanadium, cadmium, lanthanides and other chemical elements in the raw materials used for the production of mineral fertilizers. Their complete extraction is either not envisaged at all, or is complicated by technological factors. The possible content of accompanying elements in superphosphates and other types of mineral fertilizers widely used in modern agriculture is given in tables 1 and 2.

In large quantities, pollutant elements are found in lime. Its application in the amount of 5 t/ha can change the natural levels of cadmium in the soil by 8.9% of the total content.

Table 1. Content of impurities in superphosphates, mg/kg

When mineral fertilizers are applied at a dose of 109 kg/ha of NPK, approximately 7.87 g of copper, 10.25 g of zinc, 0.21 g of cadmium, 3.36 g of lead, 4.22 g of nickel, 4.77 g of chromium enter the soil . According to TsINAO data, for the entire period of using phosphate fertilizers, 3200 tons of cadmium, 16633 tons of lead, 553 tons of mercury were introduced into the soils of the former USSR. Most of the chemical elements that have entered the soil are in a weakly mobile state. The half-life of cadmium is 110 years, zinc - 510, copper - 1500, lead - several thousand years.

Table 2. Content of heavy metals in fertilizers and lime, mg/kg

Soil contamination with heavy and toxic metals leads to their accumulation in plants. For example, in Sweden, the concentration of cadmium in wheat has doubled over the current century. In the same place, when using superphosphate in a total dose of 1680 kg/ha, introduced in parts over 5 years, an increase in the content of cadmium in wheat grain by 3.5 times was observed. According to some authors, soil contamination with strontium resulted in a threefold increase in its content in potato tubers. Russia has not yet paid sufficient attention to the contamination of crop products with chemical elements.

The use of contaminated plants as food or feed is the cause of various diseases in humans and farm animals. The most dangerous heavy metals include mercury, lead and cadmium. The ingestion of lead into the human body leads to sleep disturbances, general weakness, mood deterioration, memory impairment and a decrease in resistance to bacterial infections. The accumulation of cadmium in food, the toxicity of which is 10 times higher than lead, causes the destruction of red blood cells, disruption of the kidneys, intestines, softening of bone tissue. Pair and triple combinations of heavy metals increase their toxic effect.

The WHO Expert Committee has developed standards for the intake of heavy metals into the human body. It is envisaged that every week a healthy person weighing 70 kg can receive with food, without harm to their health, no more than 3.5 mg of lead, 0.625 mg of cadmium and 0.35 mg of mercury.

In connection with the increase in food contamination, standards for the content of HMs and a number of chemical elements in crop products were adopted (Table 3).

Table 3. Maximum permissible concentrations of chemical elements, mg/kg of raw product

Element	Bread products and grains	Vegetables	Fruit	Milk products
Mercury	0,01	0,02	0,01	0,005
Cadmium	0,02	0,03	0,03	0,01
Lead	0,2	0,5	0,4	0,05
Arsenic	0,2	0,2	0,2	0,05
Copper				0,5
Zinc				5,0
Iron				3,0
Tin	-			100,0
Antimony	0,1	0,3	0,3	0,05
Nickel	0,5	0,5	0,5	0,1
Selenium	0,5	0,5	0,5	0,5
Chromium	0,2	0,2	0,1	0,1
Aluminum				1,0
Fluorine	2,5	2,5	2,5	2,5
Iodine				0,3

Contamination of crop products with HMs and chemical elements is dangerous for humans not only when it is used directly, but also when used for fodder purposes. For example, feeding cows plants grown on contaminated soils has led to an increase in the concentration of cadmium in milk up to 17-30 mg/l, while the acceptable level is 0.01 mg/l.

To prevent the accumulation of chemical elements in milk, meat, to exclude the possibility of their negative impact on the condition of farm animals, in many countries the maximum permissible concentrations (MPC) for chemical elements contained in fodder plants are adopted. According to EEC standards, the safe lead content in forage is 10 mg/kg of dry matter. In the Netherlands, the allowable level of cadmium in green fodder is 0.1 mg/kg dry weight.

The background content of chemical elements in soils is shown in Table 4. With the accumulation of HMs in the soil and their subsequent entry into plants, they are concentrated mainly in the vegetative organs, which is explained by the protective reaction of plants. An exception is cadmium, which easily penetrates both leaves and stems and generative parts. For a correct assessment of the degree of accumulation of various elements in plants, it is necessary to know their usual content when growing crops on uncontaminated soils. Information on this issue is rather contradictory. This is due to the large differences in the chemical composition of soils. The background content of lead in soils is approximately 30, and cadmium - 0.5 mg/kg. The concentration of lead in plants grown on clean soils is 0.009-0.045, and cadmium is 0.011-0.67 mg/kg of wet matter.

Table 4. Content of some elements in arable soils, mg/kg

Element	Regular content	MPC	Element	Regular content	MPC
As	0,1-20		Ni	2-50
V	5-20		Pb	0,1-20
Be	0,1-5		Sb	0,01-0,5
Vg	1-10		Se	0,01-5
CD	0,01-1		sn	1-20
So	1-10		Tl	0,01-0,5
SG	2-50		Ti	10-5000
Cu	1-20		U	0,01-1
F	50-200		V	10-100
Ga	0,1-10		Zn	3-50
hg	0,01-1		Mo	0,2-5

The establishment of strict standards for plant contamination is explained by the fact that when they are grown on contaminated soils, the content of individual elements can increase tenfold. At the same time, some chemical elements become toxic with a three- or even two-fold increase in their concentration. For example, copper content in plants is typically about 5-10 mg/kg on a dry weight basis. At a concentration of 20 mg/kg, the plants become toxic to sheep, and at 15 mg/kg, to lambs.

Chapter 2 http://selo-delo.ru/8-zemelnie-resursi?start=16

Due to the decrease in the use of mineral fertilizers, the importance organic fertilizers as a source of nutrients has increased. They are the most complete in terms of the content of nutrients needed by plants. 1 ton of bedding manure contains 5 kg N, 2.5 kg P 2 O 5 , 6 kg K 2 O; 3 - 5 g B, 25 g Zn; 3.9 g Cu, 0.5 Mo and 50 g Mn. It should be borne in mind that the cost of 1 kg of nutrients applied with solid manure is 24-37% lower than in an equivalent amount of mineral fertilizers. Organic fertilizers play an important role in increasing soil fertility and crop yields.

The application of organic fertilizers positive influence on the balance of humus in the soil, improves the air and water regime of the soil, enhances the microbiological activity of the soil. From 1 ton of organic fertilizers on loamy soils, 50 kg / ha of humus is formed, on sandy soils - 40 and sandy - 35.

Currently, about 15 t/ha of organic fertilizers are applied per 1 ha of arable land in the world. Approximately 14 t/ha is used in the USA, 25 t/ha in England, and 70 t/ha in the Netherlands. In Belarus, the use of organic fertilizers in 1991 reached 83 million tons, or 14.5 tons/ha.

V last years In the Republic of Belarus, due to the systematic reduction in the number of livestock and a sharp reduction in the volume of peat harvesting, the use of organic fertilizers has significantly decreased, which led to a decrease in the rate of accumulation of humus, and in some areas there was a decrease in the content of humus. In 1995, the use of organic fertilizers in the republic decreased to 9.5, and in 1999 to 8.2 t/ha.

One of the measures to reduce the use of organic fertilizers is the justification optimal sizes crops of perennial grasses and increase their productivity. At present, 3 hectares of perennial grasses fall on 1 ha of tilled crops. Even with a decrease in the use of organic fertilizers in recent years, due to an increase in the share of plant residues in the total volume of organic matter entering the soil from 46 to 55%, it was possible, in general, to maintain the achieved level of humus content in the soil on arable soils. To maintain a deficit-free balance of humus in the republic, it is necessary to ensure the use of organic fertilizers at the level of 50 million t/ha, or 9-10 t/ha. It is assumed that due to the increase in the number of livestock, the introduction of organic fertilizers may increase to 52.8 million tons. The republic's demand for peat is about 3 million tons.

With proper application, the payback of 1 ton of organic fertilizers is: for cereals - 20 kg, potatoes - 90, fodder root crops - 200, corn (green mass) - 150 kg.

The following types of organic fertilizers are used in agriculture:

1. Organic fertilizers based on animal and poultry waste:

a) bedding manure;

b) bedless manure;

c) slurry;

d) bird droppings;

2. Fertilizers from natural organic raw materials:

b) composts;

3. Green manure and use of crop by-products:

a) straw

b) green manure;

4. Organic fertilizers based on municipal and industrial waste:

a) industrial and domestic waste;

b) sewage sludge;

c) hydrolytic lignin.

bedding manure- a mixture of liquid and solid animal excrement with bedding. Liquid animal excrement refers to potassium-nitrogen fertilizer, and solid - to nitrogen-phosphorus (Table 5.1).

The quality of the manure chemical composition depend: 1) on the type of feeding; for example, when containing concentrates in the diet, manure contains more nutrients than when feeding with roughage; 2) animal species (Table 5.2); 3) quantity and type of litter; 4) storage method (Table 5.3; 5.4)

Various bedding materials contain the following amounts of nutrients:

With a loose or hot method of storage, when the manure is not compacted, aerobic conditions are created, thermophilic bacteria develop, the temperature inside the pile reaches 50 - 60 0 C. There is a rapid decomposition of organic matter, nitrogen volatilizes in the form of NH 3 , there are losses Р 2 O 5 and K 2 A. Losses of nitrogen during loose storage - about 30%.

T a b l e 5.1. The content of dry matter, nitrogen and ash elements in animal excrement, % http://www.derev-grad.ru/himicheskaya-zaschita-rastenii/udobreniya.html

With hot-pressed, or loose-dense, storage method (Krantz method), manure of loose laying after heating to 50 - 60 0 C is compacted. First, aerobic conditions are created, then anaerobic ones. Nitrogen and organic matter losses are reduced.

There is also a cold, or dense, storage method when anaerobic conditions are created. The manure in the heaps is immediately compacted. This The best way storage in terms of nutrient retention. In this case, a constant temperature is maintained in the piles (15 - 35 0 WITH). Nitrogen losses are small, since the manure is always in a dense and wet state. Air access to such manure is limited, and water-free pores are occupied by carbon dioxide, which slows down microbiological activity.

Depending on the degree of decomposition, manure on a straw bed is divided into fresh, semi-rotted and humus.

In fresh slightly decomposed manure, straw slightly changes color and strength. When semi-ripened, it acquires a dark brown color, becomes less durable and breaks easily. At this stage of decomposition, manure loses 10 - 30% of its original mass and the same amount of organic matter. It is unprofitable to bring manure to the stage of humus, since in this case about 35% of organic matter is lost.

Weakly decomposed manure in the first year may have a weak effect, and in the aftereffect in the second and third years there may be relatively high yield increases. If there are different degrees of manure decomposition on the farm, more decomposed manure in areas of sufficient moisture can be applied in the spring for tilled crops, and less decomposed manure in the summer after harvesting annual grasses for winter crops.

T a b l e 5.2. Chemical composition of fresh manure, %

	Manure on a straw bed	Manure on peat bed
Components	cattle	horse	sheep	pork	cattle	horse
Water	77,3	71,3	64,4	72,4	77,5	67,0
Organ. substance	20,3	25,4	31,8	25,0	-	-
Nitrogen: total	0,45	0,58	0,83	0,45	0,60	0,80
ammoniacal	0,14	0,19	-	0,20	0,18	0,28
Phosphorus	0,23	0,28	0,23	0,19	0,22	0,25
Potassium	0,50	0,63	0,67	0,60	0,48	0,53

It is irrational to apply bedding manure to the soil in a fresh form, since mobilization of mobile forms of nitrogen by microorganisms can occur, and plants at the beginning of the growing season will not receive it in sufficient quantities. In addition, fresh manure contains weed seeds. Therefore, matured, semi-rotted manure should be used on farms. When harvesting organic fertilizers in winter period it is necessary to extend the terms of their composting and storage, and the application should be made in the summer-autumn period. This will allow you to get high-quality manure, free from weeds and pathogenic microflora.

Table 5.3. Effect of bedding manure storage methods on losses of organic matter and nitrogen, %

T a b l e 5.4. The content of nutrients in manure on straw bedding depending on the degree of its decomposition, %

For manure good quality it is stored in manure storages or in field piles.

Manure storages. When laying stacks, they strive to ensure that manure of varying degrees of decomposition is not mixed, but is located in separate parts of the manure storage. Laying manure in piles 2 - 3 m wide begins along the side of the store, which is adjacent to the slurry collector. Manure is laid small areas, compacting each meter layer of manure, and then bring to full height (1.5 - 2 m). After the first stack is completely laid, along it, as manure arrives, the second stack is laid in the same way, then the third, etc. until the manure storage is full. Stacks should be tightly adjacent to each other. With this order of bookmarking, on one side of the manure storage there will be more decomposed manure, and on the other - less decomposed, which will allow the use of manure the right quality

3) Chapter 4 Application of organo-mineral complexes to improve soil fertility

Organomineralnye fertilizers http://biohim-bel.com/organomineralnye-udobreniya

The soil cannot be permanently fertile if it is not fertilized. Various substances, usually mineral or organic, are used to improve soil properties. These species differ from each other in nutrient saturation. Each of these types has its own advantages and disadvantages. So, for example, organic fertilizers do not always contain full complex substances necessary to ensure the most comfortable conditions for the plant. In this case, organic fertilizers are supplemented with mineral ones. An example is humus or ash, which contain very little nitrogen. To make the soil more fertile, these agents are used in combination with mineral nitrogen agents. In addition, the use of untested organic fertilizers can contribute to the infection of the plant with some kind of infection.

Agricultural technology for growing vegetable, fruit and berry and ornamental crops provides for the mandatory introduction of organic and inorganic top dressings into the soil. The positive effect of mineral fertilizers on the growth and development of plants has long been beyond doubt.
Even ardent adherents of organic farming are forced to recognize the need to use compounds of nitrogen, phosphorus, potassium, microelements to increase green mass and fully ripen fruits.

The effect of nitrogen fertilizers on plants

Nitrogen is one of the most essential elements for plant growth. Fertilizers are applied directly to the soil during spring digging (urea) and in dissolved form (ammonium nitrate).
The first signs of nitrogen deficiency are weak and stunted shoots, leaves with yellowness or pale green. Within two or three days after feeding, the plants literally “come to life” before our eyes. The stems become stronger, and the green mass acquires a characteristic rich color.
Also, a lack of nitrogen can also manifest itself in poor ripening of fruits. A low protein content leads to a sharp deterioration in their taste and appearance.

To the main benefits nitrogen fertilizers can be attributed:

• they can be used on different types soils;
• ensure rapid growth of plants;
• I contribute to increasing the yield and quality of ripened fruits.

The effect of nitrogen fertilizers on the growth and development of plants is especially important in the phase of growing green mass, since its lack will lead to further dropping of color and fruits.
It should be borne in mind that, starting from the moment of fruit set, the use of nitrogen should be excluded, since the natural growth of plants slows down, and fruit trees and shrubs must prepare for winter.

Potash fertilizers - effect on plants

Potassium as an element is necessary to increase productivity, resistance to drought, low temperatures, and fungal diseases. The first signs of potassium starvation are a barely noticeable wilting of the leaves and a decrease in their elasticity, the appearance of a white border along the edge of the leaf, which subsequently turns brown.
With timely fertilization, the plants quickly recover and normalize growth and fruiting.
Effect of fertilizers on potato yield and quality
Potato is one of the most popular crops in Russia. As a rule, it is grown on the same areas, which requires compliance with certain agricultural practices. For getting good harvests green manure cultivation and timely fertilization are recommended. In the fall, when digging, ordinary or double superphosphate is added, in the spring, when planting, potash or complex fertilizers with a high content of the active element are added. Potato belongs to potassium-loving plants, with its lack of taste and quality of tubers deteriorates.

The effect of phosphorus-containing mineral fertilizers on productivity

Effect of mineral fertilizers on soil microorganisms

Scientifically proven fact - mineral fertilizers under favorable climatic conditions increases the activity of microorganisms. The physical properties of the soil do not change, the level of humus practically remains the same (the studies were started on the basis of TSCA by academician Pryanishnikov D.N.).

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

So, let's sum up.
Plants with their fruits and their humus (leaves, stems, roots, etc.) attract soil microflora 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 organic matter, making the so-called broth, which they "eat" themselves and which the plants "eat". Then some of the bacteria that multiply strongly in the process of feeding are eaten by earthworms. Digesting bacteria and the remains 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 introduces tons of chemicals into the earth, disrupting the harmonious balance of microflora.

It is now clear that soil fertility depends on the health of soil microflora.
But herbicides and pesticides kill this microflora. Kill completely. Proof of this, our friend the farmer - he says that where he does not put mineral fertilizers, potatoes do not grow there at all - the bushes grow up to 10 cm in height and that's it, the tubers do not want to tie at all. And he believes that there is only one way out - to put more mineral fertilizers. And every year more and more...

Plants on mineral fertilizers are drug addicts. These plants are "sitting 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 site about gardening: " mineral fertilizers change the qualitative composition of soil microorganisms, destroy humic acid molecules, fertility is disturbed or disappears altogether, since soil structure is disturbed, 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 is another article for you 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 harvest from them is growing,

But nature is being destroyed.

People eat nitrates

More and more every year.

The global production of mineral fertilizers is growing rapidly. Every decade it increases by about 2 times. The yield of crops from their use, 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 has been proven that about 40% of the nitrogen introduced into the soil is absorbed by plants, the rest of the nitrogen is washed out of the soil by rain and volatilizes in the form of gas. To a lesser extent, but washed out of the soil and phosphorus. 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 settle to the bottom of water bodies, this leads to the release of methane, hydrogen sulfide and a reduction in water-soluble oxygen reserves, which causes fish to die. The species composition of valuable fish is also declining. The fish did not grow to normal sizes, it began to age earlier, to die earlier. Plankton in water bodies accumulate 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 Construction Materials that oxidize metals. Forests and the animals and birds living in them suffer from all this, and fish and mollusks die in reservoirs. There is a report that on some plantations where mussels are mined (these are edible mollusks, they used to be very much appreciated), they became inedible, moreover, there were cases of poisoning by them.

INFLUENCE OF MINERAL FERTILIZERS ON SOIL PROPERTIES

Observations show that the content of humus 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 left. Podzolic and soddy-podzolic soils contain 0.5-3% humus, gray forest soils - 2-6%, meadow chernozems - more than 6%. Humus serves as a repository of the main plant nutrients, it is a colloidal substance, the particles of which hold the nutrients on their surface in a form accessible to plants. Humus is formed during the decomposition of plant residues by microorganisms. Humus cannot be replaced by any mineral fertilizers, on the contrary, they lead to active mineralization of humus, the soil structure deteriorates, from colloidal lumps that retain water, air, nutrients, the soil turns into a dusty substance. From natural soil turns into 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, soil acidification, which inevitably occurs when mineral fertilizers are applied, requires an increasing amount of lime. In 1986, 45.5 million tons of lime were applied to the soil in our country, but this did not compensate for the loss of calcium and magnesium.

SOIL POLLUTION WITH 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 are included in superphosphates, in potash fertilizers. The most dangerous heavy metals: mercury, lead, cadmium. The latter destroys erythrocytes in the blood, disrupts the functioning of the kidneys, intestines, and softens tissues. A healthy person weighing 70 kg without harm to health can receive with food per week up to 3.5 mg of lead, 0.6 mg of cadmium, 0.35 mg of mercury. However, on heavily fertilized soils, plants can accumulate high concentrations of these metals. For example, in the milk of cows there can be up to 17-30 mg of cadmium per 1 liter. The presence of uranium, radium, thorium in phosphate fertilizers increases the level of internal exposure of humans and animals when plant foods enter their bodies. 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 THE LIVING WORLD OF SOIL

The use of mineral fertilizers causes a change in the species composition of soil microorganisms. The number of bacteria capable of assimilating mineral forms of nitrogen greatly increases, but the number of symbiotic microfungi in the plant rhizosphere decreases (the rhizosphere is a 2–3 mm soil area adjacent to the root system). The number of nitrogen-fixing bacteria in the soil also decreases - 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 above-ground part, and plant photosynthesis is reduced. Toxin-forming microfungi are activated, the number of which is naturally controlled by beneficial microorganisms. The introduction of lime does not save the situation, but sometimes leads to an increase in soil contamination with root rot pathogens.

Mineral fertilizers cause severe depression of soil animals: springtails, 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 enzymes enter the soil as a result of their release by living organisms, dying 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 enter food are absorbed into the digestive tract, enter 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; it is unable to carry oxygen. The norm of metahemoglobin in the body is 2%, and more of it causes various diseases. At 40% methaemoglobin 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. Nitrosamines, 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 embryotoxic properties.

For vegetables, limit norms for the content of nitrates in mg / kg have been established. These standards are constantly being adjusted upwards. The level of the maximum permissible concentration of nitrates, adopted now in Russia, and optimal acidity soils for some vegetables are given in the table (see below).

The actual content of nitrates in vegetables, as a rule, exceeds the norm. Maximum daily dose nitrates, which does not have a negative effect on the human body, - 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. By increasing the yield of crops, mineral fertilizers affect their quality. In plants, the content of carbohydrates 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 the cultivation of 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 keeping quality during storage. In potatoes, the flesh darkens more strongly; when canning vegetables, nitrates cause corrosion of the metal of cans. It is known that nitrates are more in the veins of leaves in lettuces, 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 when juice and vegetables are stored at high temperature. It is better to harvest vegetables from the garden when they are ripe and in the afternoon - then they have less nitrates. Where do nitrates come from, and when did this problem arise? Nitrates have always been in the products, just their number 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 amount of this nitrogen in the tissues. Nitrates by themselves are not dangerous. Some of them are excreted from the body, the other part is converted into harmless and even useful compounds. And the excess part of nitrates turns into salts of nitrous acid - these are nitrites. They also deprive the red blood cells of the ability to nourish the cells of our body with oxygen. As a result, metabolism is disturbed, the central nervous system suffers, and 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.

Fertilizers replenish the reserves of nutrients in the soil in an accessible form and supply them to plants. At the same time, they have a great influence on the properties of the soil and thus also affect the yield indirectly. By increasing the yield of plants and the mass of roots, fertilizers enhance positive action plants on the soil, contribute to an increase in humus in it, improve its chemical, water-air and biological properties. Organic fertilizers (manure, composts, green manure) have a great direct positive effect on all these soil properties.
Acidic mineral fertilizers, if they are systematically applied without organic fertilizers (and on acidic soils without lime), can have a negative effect on soil properties (Table 123). Their long-term use on acidic soils without liming leads to a decrease in the saturation of the soil with bases, increases the content of toxic aluminum compounds and toxic microorganisms, and worsens water-physical properties soil, increases volume weight(density), reduces soil porosity, its aeration and water permeability. As a result of the deterioration of soil properties, the increase in yields from fertilizers is reduced, and the “hidden negative effect” of acid fertilizers on the crop is manifested.

The negative effect of acidic mineral fertilizers on the properties of acidic soils is associated not only with the free acidity of fertilizers, but also with the effect of their bases on the absorbing complex of the soil. By displacing exchangeable hydrogen and aluminum, they convert the exchangeable acidity of the soil into active acidity and, at the same time, strongly acidify the soil solution, dispersing the colloids that hold the structure together and reducing its strength. Therefore, when applying large doses of mineral fertilizers, not only the acidity of the fertilizers themselves, but also the exchangeable acidity of the soil should be taken into account.
Lime neutralizes the acidity of the soil, improves its agrochemical properties and eliminates the negative effect of acidic mineral fertilizers. Even small doses of lime (from 0.5 to 2 t/ha) increase the saturation of the soil with bases, reduce acidity and sharply reduce the amount of toxic aluminum, which in acidic podzolic soils has an extremely strong negative effect on plant growth and yield.
In long-term experiments with the use of acidic mineral fertilizers on chernozems, a slight increase in soil acidity and a decrease in the amount of exchangeable bases are also noted (Table 124), which can be eliminated by adding small quantities lime.

Organic fertilizers have a great and always positive effect on all soils. Under the influence of organic fertilizers - manure, peat composts, green manure - the content of humus increases, the saturation of the soil with bases, including calcium, improves the biological and physical properties of the soil (porosity, moisture capacity, water permeability), and in soils with an acidic reaction, acidity, content toxic aluminum compounds and toxic microorganisms. However, a significant increase in the content of humus in the soil and an improvement in its physical properties are noted only with the systematic introduction of large doses of organic fertilizers. Their single application to acidic soils together with lime improves the qualitative group composition of humus, but does not lead to a noticeable increase in its percentage in the soil.
Similarly, peat introduced into the soil without prior composting does not have a noticeable positive effect on soil properties. Its influence on the soil increases dramatically if it is previously composted with manure, slurry, feces or mineral fertilizers, especially alkaline ones, since peat itself decomposes very slowly and in acidic soils forms a lot of highly dispersed fulvic acids that support the acidic reaction of the environment.
The joint application of organic fertilizers with mineral fertilizers has a great positive effect on the soil. At the same time, the number and activity of nitrifying bacteria and bacteria that fix atmospheric nitrogen, oligonitrophils, free-living nitrogen fixers, etc., increase especially sharply. a large number of strong acids that podzolize the soil.

Every owner is engaged in fertilizing the soil suburban area who has a desire to get a harvest from the crops grown. What fertilizers are, we have already considered the norms of their soil in our previous articles. Today we want to pay attention to the effect of fertilizers on plants and humans.

Indeed, why are fertilizers needed and how do they affect certain indicators of crop growth, and even on the person himself? We will answer these questions right now.

Such topics are often raised at the global level, because the conversation is not about a small piece of land, but about industrial-scale fields to meet the needs of an entire region or even a country. It is clear that the number of fields for crops is constantly growing, and each field once cultivated forever becomes a platform for growing certain plants. Accordingly, the land is depleted, and every year the harvest is significantly reduced. This leads to expenses, and sometimes to bankruptcy of enterprises, hunger, deficits. The primary reason for everything is the lack of nutrients in the soil, which we have long been compensating for with special fertilizers. Of course, it is not entirely correct to give an example of multi-hectare fields, but the results can be recalculated for the area of ​​our summer cottages because everything is proportional.

So, fertilizing the soil. Of course, it is extremely necessary, whether it is a garden with fruit trees, a vegetable garden, or a flower bed with ornamental plants and flowers. You may not fertilize the soil, but you yourself will soon notice the quality of plants and fruits on constant, depleted soil. Therefore, we recommend that you do not save on high-quality fertilizers and systematically fertilize the land with them.

Why fertilizers are needed (video)

Fertilizer application rates

We are used to using predominantly, but their number is limited. What to do in this case? Of course, seek help from chemistry, and fertilize the site, which, fortunately, we do not end. But, with this type of fertilizer, you should be more careful, as they have an increased impact on soil quality for plants, humans and environment . The right amount of them will surely supply the soil with nutrients that will soon be “delivered” to the plants and help increase yields. At the same time, mineral fertilizers normalize the required amount of substances in the soil and maximize its fertility. But, this is only if the fertilizer dose, application time and other parameters are performed correctly. If not, then the effect of nitrogen fertilizers, phosphate and potash fertilizers on the soil may not be very positive. Therefore, before using such fertilizers, try not only to study the norms and parameters of their application to the soil, but also to choose high-quality mineral fertilizers, the safety of which has passed the control of the manufacturer and special authorities.

The effect of organic fertilizers on the content of trace elements in the soil (video)

The effect of fertilizers on plants

Excess

With the help of practical research, scientists have found out how certain fertilizers affect plants. Now, according to external indicators, you can understand how correct the dosage of fertilizers was, whether there was an oversupply or a deficiency:

• Nitrogen. If there is too little fertilizer in the soil, the plants look pale and sickly, have a light green color, grow very slowly and die prematurely from yellowing, dryness and leaf fall. An excess of nitrogen leads to a delay in flowering and ripening, excessive development of the stems and a change in the color of the plant to dark green;
• Phosphorus. A lack of phosphorus in the soil leads to stunted growth and slow ripening of fruits, a change in the color of the leaves of the plant towards dark green with a certain bluish tint, and lightening or gray along the edges. If there is a lot of phosphorus in the soil, then the plant will develop too quickly, because of which it can go into the growth of the stem and leaves, while the fruits at this time will be small and in small quantities;
• Potassium. A lack of potassium will provide the plant with slow development, yellowing of the leaves, their wrinkling, twisting and partial death. An excess of potassium closes the pathways for nitrogen to enter the plant, which can significantly affect the development of a plant of any crop;
• Calcium. A small intake of potassium will damage the apical buds, as well as the root system. If there is plenty of potassium, then no changes should follow.

Flaw

With the rest of the elements, everything is a little different, that is, the plants will only react to their lack in the soil. So:

• Magnesium. Slow growth, and possibly its stop, lightening of the plant, yellowing, and possibly redness and the acquisition of a purple hue in the area of ​​​​the leaf veins;
• Iron. Growth and development retardation, as well as leaf chlorosis - light green, sometimes almost white in color;
• Copper. Leaf chlorosis, increased bushiness of the plant, discoloration are possible;
• Bor. The lack of boron causes the death of the apical buds in the process of decay.

It is worth noting the fact that it is often not the lack of fertilizer itself that makes plants change in appearance, but the weakening of the plant and the diseases that can occur with a lack of fertilizer. But, as you can see, it is possible Negative consequences and over-fertilization.

The effect of fertilizer on the quality and condition of fruits (video)

The effect of fertilizers on humans

An excess of nutrients in the soil, due to improper fertilization, can become dangerous for humans. Many chemical elements, getting into the plant through biological processes, are transformed into poisonous elements, or contribute to their production. Many plants initially contain such substances, but their doses are negligible and do not affect the healthy life of a person. This is typical of many popular plants that we eat: dill, beets, parsley, cabbage, and so on.