Possible negative impact of fertilizers on soil fertility. The effect of mineral fertilizers on the growth and development of plants The effect of fertilizers on soil properties

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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 the physical characteristics of the arable layer. The main indicators of the physical properties of the soil are the 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-cultivating 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, the negative effect of 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, deterioration biological properties should naturally be accompanied by a deterioration in agrophysical properties.

In order to prevent negative influence 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 admission to human body heavy metals. It is expected that every week healthy man 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 Dairy
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 polluted 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 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 in plants various elements 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
AT 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 of organic fertilizers as a source of nutrients has increased. They are the most complete in terms of nutrient content, 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.

In recent years, in the Republic of Belarus, due to a 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 humus content. 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) precipitation Wastewater;

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 concentrated in the diet, manure contains more nutrients than when fed 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. it The best way storage in terms of nutrient retention. In this case, a constant temperature is maintained in the piles (15 - 35 0 FROM). 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 is a different degree of manure decomposition on the farm, more decomposed manure in areas of sufficient moisture can be applied in 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

Bedding manure is irrational to introduce into the soil in fresh, since the 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 the 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 of the desired 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. Used to improve soil properties various substances usually mineral or organic. 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 the full range of substances necessary to ensure maximum comfortable conditions for a 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.

The application of fertilizers to the soil not only improves plant nutrition, but also changes the conditions for the existence of soil microorganisms, which also need mineral elements. Under favorable climatic conditions, the number of microorganisms and their activity after fertilizing the soil increase significantly.

The stimulating effect of mineral fertilizers on soil microflora, and even more so on manure, is very clearly demonstrated by an experiment conducted on soddy-podzolic soil of the Agricultural Academy. K.A. Timiryazev (E.N. Mishustii, E.3. Tepper). More than 50 years ago, on the initiative of D.N. Pryanishnikov, a stationary long-term experiment was laid to study the effect of various fertilizers on the soil. For microbiological research, samples were taken from the following plots.

Permanent fallow: 1) unfertilized soil; 2) soil that received mineral fertilizer annually; 3) soil fertilized annually with manure.

Permanent rye: 1) unfertilized soil; 2) soil that received NRK annually; 3) soil fertilized annually with manure.

Seven-field crop rotation with clover: 1) unfertilized soil (fallow); 2) soil fertilized annually with manure (steam).

On average, soils fertilized with mineral fertilizers received 32 kg of nitrogen, 32 kg of phosphorus (P 2 0 5) and 45 kg of potassium (K 2 0) per 1 ha per year. Manure was applied in the amount of 20 tons per 1 ha annually.

Table 1

Fertilizers applied

Total number of microorganisms, thousand per 1 ha

Number of actinomycetes, thousand per 1 g

Actinomycetes, %

The total number of mushrooms, (thousand per 1 ha)

Permanent fallow unfertilized NPK

Permanent rye

unfertilized

7 - Full crop rotation

unfertilized steam

Manure, steam

As follows from the data in Table 1, the soils that were fallow for a long time were greatly depleted in microorganisms, since fresh plant residues did not enter them. The highest number of microorganisms was in the soil under permanent rye, where plant residues were received in significant quantities.

The application of mineral fertilizers to the soil, which was all the time in a state of fallow, markedly increased the overall biogenicity. The use of mineral fertilizers did not have a significant impact on the number of soil micropopulation under permanent rye.

In most cases, mineral fertilizers somewhat reduced the relative abundance of actinomycetes and increased the content of fungi. This was the result of some soil acidification, which negatively affects the first group of soil micropopulations and enhances the reproduction of the second. In all cases, manure sharply stimulated the reproduction of microorganisms, since a rich complex of mineral and organic substances is introduced into the soil with manure.

The differences in the fertilizer system dramatically affected the properties of the soil and its productivity. The soil, which was in a fallow state for 50 years, lost about half of the humus reserve. The application of mineral fertilizers significantly reduced this loss. Fertilizers stimulated the formation of humus by microbes.

The average yield for the period of experience is given in table. 2, compiled on the basis of data from V. E. Egorov.

table 2

The effect of different fertilizers applied to soddy-podzolic soil on crop yields (in c/ha)

In crop rotation, yields were significantly higher than with permanent crops. In all cases, however, fertilizer significantly increased the yield. More effective was complete organic fertilizer, i.e. manure.

Mineral fertilizers usually have a "Physiological" acidity. When used by plants, acids accumulate, acidifying the soil. Humus and silty soil fractions can neutralize acidic substances. In such cases, one speaks of the "buffer" properties of the soil. In the example analyzed by us, the soil had well-pronounced buffer properties and long-term use of fertilizers did not lead to a significant decrease in the pH value. As a result, the activity of microorganisms was not suppressed. There was also no harmful aftereffect of fertilizers on plants.

In light sandy soils, buffering is weakly expressed. Prolonged use of mineral fertilizers on them can lead to strong acidification, as a result of which toxic aluminum compounds pass into the solution. As a result, the biological processes in the soil are suppressed, and the yield decreases.

A similar unfavorable effect of mineral fertilizers was observed on light sandy loamy soils of the Solikamsk agricultural station (E. N. Mishustin and V. N. Prokoshev). For the experiment, a three-field crop rotation was taken with the following alternation of crops: potatoes, rutabaga, spring wheat. N and P 2 0 5 were annually introduced into the soil at 90 kg / ha, and K 2 0 - 120 kg / ha. Manure was given twice every three years at 20 t/ha. Lime was applied on the basis of total hydrolytic acidity - 4.8 t/ha. Before the microbiological study of the soil, four rotations took place. In table. Table 3 gives data characterizing the state of individual groups of microorganisms in the studied soils.

Table 3

The influence of different fertilizers on the microflora of podzolic sandy soil of the Solikamsk agricultural station

From the data in the table it follows that the use of NRK for a number of years significantly reduced the number of microorganisms in the soil. Only mushrooms were not affected. This was due to significant soil acidification. The introduction of lime, manure and their mixtures stabilized soil acidity and favorably affected the soil micropopulation. The composition of cellulose microorganisms has noticeably changed due to soil fertilization. On more acidic soils, fungi predominated. All types of fertilizers contributed to the reproduction of myxobacteria. The introduction of manure increased the reproduction of Sutorhaga.

Of interest are the data illustrating the yields of agricultural crops on soils fertilized differently at the Solikamsk agricultural station (Table 4).

Table 4

Effect of fertilizers applied to sandy soil on crop yields (c/ha)

The figures in the table show that mineral fertilizers gradually reduced the yield, and wheat began to suffer earlier than potatoes. The manure had a positive effect. In general, the microbial population reacted to changes in the soil background in much the same way as vegetation.

On neutral buffer soils, mineral fertilizers, even with their long-term use, have a positive effect on soil microflora and plants. In table. 5 shows the results of an experiment in which the chernozem soils of the Voronezh region were fertilized with various mineral fertilizers. Nitrogen was applied at the rate of 20 kg/ha, P 2 0 5 -60 kg/ha, K 2 O - 30 kg/ha. The development of soil micropopulation has intensified. However, high doses of fertilizers used for a long time can also lower the pH and inhibit the growth of microflora and plants. Therefore, with intensive chemicalization, the physiological acidity of fertilizers should be taken into account. Radial microzones are created around the pieces of mineral or organic fertilizers in the soil, containing different concentrations of nutrients and having different pH values.

Table 5

Influence of mineral fertilizers on the number of microflora of the chernozem soil (in thousand/g)

In each of these zones, a peculiar grouping of microorganisms develops, the nature of which is determined by the composition of fertilizers, their solubility, etc. Thus, it would be a mistake to think that fertilized soils have the same type of microflora at all points. Microzoning, however, is also characteristic of unfertilized soil, as mentioned earlier.

Strengthening the reproduction of microorganisms in fertilized soils affects the activation of processes occurring in the soil. So, the release of CO 2 by the soil (“breathing” of the soil) is noticeably increased, which is a consequence of a more vigorous destruction of organic compounds and humus. It is clear why, in fertilized soils, plants, along with the introduced elements, use large amounts of nutrients from soil reserves. This is especially evident in relation to nitrogen compounds in the soil. Experiments with mineral nitrogen fertilizers labeled with N 15 showed that the amount of soil nitrogen mobilization under their influence depends on the type of soil, as well as the dosages and forms of the compounds used.

The increased activity of microorganisms in fertilized soils simultaneously leads to the biological fixation of some of the introduced mineral elements. Some of the mineral nitrogen-containing substances, such as ammonium compounds, can be fixed in the soil and due to physicochemical and chemical processes. Under the conditions of a vegetation experiment, up to 10–30% of the dispersed nitrogen fertilizers, and in the field - up to 30--40% (A.M. Smirnov). After the death of microorganisms, the nitrogen of their plasma is partially mineralized, but partially passes into the form of humus compounds. Up to 10% of nitrogen fixed in the soil can be used by plants next year. The rest of the nitrogen is released at about the same rate.

Features of microbiological activity in different soils affect the conversion of nitrogen fertilizers. They are significantly influenced by the technique of introducing mineral fertilizers. Pelleting, for example, reduces the contact of fertilizers with the soil and hence with microorganisms. This significantly increases the fertilizer utilization rate. All of the above applies to a large extent to phosphate fertilizers. Therefore, the importance of taking into account the microbiological activity of the soil in the development of questions of the rational use of fertilizers becomes clear. Biological fixation of potassium in the soil occurs in relatively small quantities.

If nitrogen fertilizers, along with other mineral compounds, activate the activity of saprophytic microflora, then phosphorus and potassium compounds enhance the activity of free-living and symbiotic nitrogen fixers.

Plants need nutrients to grow and develop. Some of them are green spaces obtained directly from the soil, and some are extracted from mineral fertilizers. Artificial soil mineralization allows you to get big crops, but is it safe? So far, modern breeders have not been able to get an unequivocal answer to this question, but research in this area continues.

Benefit or harm?

Many mineral fertilizers are considered harmful to human health, and the plants that have absorbed them are almost poisonous. In fact, this statement is nothing more than an established stereotype based on the lack of agrotechnical knowledge.

Important! The difference between organic and mineral fertilizers is not at all in the benefits or harms, but in the speed of assimilation.

Organic fertilizers are absorbed slowly. In order for a plant to get the substances it needs from organic matter, it must decompose. The microflora of the soil is involved in this process, which significantly slows it down. Weeks and even months pass from the moment natural dressings are introduced into the soil and before they are used by plants.

Mineral fertilizers enter the soil already in finished form. Plants get access to them immediately after application. This has a positive effect on the growth rate and allows you to harvest a good harvest even where normal conditions like this is impossible. Unfortunately, this is where the positive aspects of using mineral supplements in most cases end.

Improper use of them can lead to:

  • the disappearance from the soil of bacteria involved in the natural process of decomposition;
  • pollution of groundwater and the atmosphere (the pollution involves individual components of mineral fertilizers washed out of the soil before they are absorbed by plants);
  • changes in soil acidity;
  • accumulation in the soil of compounds atypical for the natural environment;
  • leaching of useful cations from the soil;
  • decrease in the amount of humus in the soil;
  • soil compaction;
  • erosion.

A moderate amount of minerals in the soil is good for plants, but many vegetable growers use more fertilizer than they need. Such irrational use leads to saturation with minerals not only of the root and stem, but also of that part of the plant that is intended for human consumption.

Important! Compounds atypical for a plant affect health, provoke the development of diseases.

Pesticides and pesticides

In order for the plant to grow and develop quickly, fertilizers applied to the soil are not enough. You can get a good harvest only by protecting it from pests. For this purpose, farmers use various pesticides and pesticides. The need for their use arises in the case of:

  • lack of natural means to combat the invasion of insects (fields are treated against locusts, moths, etc.);
  • infection of plants with dangerous fungi, viruses and bacteria.

Pesticides and pesticides are used to control weeds, rodents and other pests. Chemicals are selected in such a way that they affect only specific rodents, a variety of weeds or pests. Cultivated plants that have been treated along with weeds do not experience the negative effects of chemicals. Processing does not affect their appearance in any way, but pesticides and pesticides are deposited in the soil and, together with minerals, first penetrate the plant itself, and from there into the person who used it.

Unfortunately, the chemical treatment of fields in most cases is the only way to obtain good harvest. Significant sown areas do not leave alternative ways problem solving. The only way out is to track the quantity and quality of pesticides used. For this purpose, special services have been created.

Negative influence

The greatest harm to the environment and humans is caused by various aerosols and gases sprayed over large areas. Improper use of pesticides and fertilizers is fraught with serious consequences. In this case, the negative impact can manifest itself years and decades later.

Impact on a person

When using fertilizers and pesticides, you must follow the instructions. Failure to comply with the rules for applying top dressings and chemicals can lead to poisoning not only of the vegetable itself, but also of a person. So, if an unreasonably high dose of nitrogen got into the soil, with a minimum content of phosphorus, potassium and molybdenum in it, nitrates dangerous for the human body begin to accumulate in plants.

Vegetables and fruits rich in nitrates affect the gastrointestinal tract, increase the risk of developing cancer. Under influence a large number chemicals and fertilizers, the biochemical composition of food is modified. Vitamins and nutrients almost completely disappear from them, they are replaced by dangerous nitrites.

A person who regularly consumes vegetables and fruits treated with chemicals and grown exclusively on mineral fertilizers often complains about headache, palpitations, muscle numbness, visual and hearing impairments. Such vegetables and fruits cause the greatest harm to pregnant women and children. An excess of toxins in the body of a newborn can have unpredictable consequences.

Soil impact

As mentioned above, mineral fertilizers and chemicals negatively affect, first of all, the soil. Improper use of them leads to the depletion of the soil layer, changes in the structure of the soil, erosion. Yes, caught in ground water nitrogen stimulates the growth of vegetation. Organic matter accumulates in the water, the amount of oxygen decreases, swamping begins, due to which the landscape in this area can irreversibly change. Soils saturated with minerals and poisons can dry out, fertile chernozems cease to produce high yields, less fertile soils oh and nothing but weeds grows at all.

Environmental impact

Not only fertilizers have a negative impact, but also the process of their production. Lands on which new types of fertilizers are tested are rapidly leaching, losing their natural fertile layer. Transportation and storage of chemicals are no less dangerous. People in contact with them are required to use gloves and respirators. Fertilizers must be stored in a place specially designated for this, where children and pets will not have access. Failure to follow simple precautions can provoke a real environmental disaster. So, some pesticides can cause massive fall of foliage from trees and shrubs, wilting of herbaceous vegetation.

In order to use mineral fertilizers without consequences for the environment, soils and health, farmers must adhere to the following rules:

  • organic fertilizers are used wherever possible (modern organics are not a complete, but good enough replacement for mineral fertilizers);
  • before using fertilizers, read the instructions (when choosing them Special attention paid to the composition of soils, the quality of the fertilizers themselves, the variety and type of crop grown);
  • top dressing is combined with soil acidification measures (lime or wood ash is added along with minerals);
  • use only those fertilizers that contain the minimum amount of harmful additives;
  • the timing and dose of minerals are not violated (if nitrogen fertilization should be done in early May, then using this fertilizer in early June may be wrong and even dangerous).

Important! To minimize the negative effect of non-natural supplements, farmers alternate them with organics, which helps to reduce nitrate levels and reduce the risk of intoxication.

It will not be possible to completely abandon pesticides, but in the conditions of a small farm, their use can be minimized.

Conclusion

The use of mineral fertilizers and pesticides simplifies the work of the farmer, allowing you to get a significant amount of the crop with minimal cost. The cost of top dressing is low, while their introduction increases soil fertility several times. Despite the existing risk of harm to the soil and human health, using mineral supplements farmers can grow cultivated plants previously unwilling to take root.

Soil mineralization increases the resistance of plants to pests and diseases, allows you to store the resulting product longer than usual and improve its presentation. Fertilizers can be easily applied even without special agrotechnical education. Using them has both pros and cons, as described in more detail above.

Preservation and reproduction of soil fertility is a task of exceptional importance. This is of particular importance in modern agricultural conditions with a shortage of fertilizers and their high cost. The use of organic and mineral fertilizers is the most significant factor contributing to the preservation and improvement of soil fertility along with the impact on the overall level of crop yields.

The most important indicator of soil fertility is the content of organic matter, or humus, in the soil.

Humus affects the thermal, water, air properties of the soil, its absorption capacity and biological activity, it largely determines the agrophysical, physicochemical, agrochemical properties of the soil, and also serves as a reserve source of nutrients for plants. The yield of agricultural crops depends on the reserves of humus in the soil.

With insufficient fertilization, the crop yield is formed mainly due to soil reserves of nutrients, primarily nitrogen, released during the mineralization of humus.

To maintain a deficit-free balance of humus, the use of manure (or other organic fertilizers in equivalent amounts, depending on the degree of humification) should be 7–15 t/ha per year.

The results of many years of research in field experiments on soddy-podzolic soils of various granulometric composition show that when growing crops without fertilization, there is a significant decrease in organic matter in soils compared to the initial level and, as a result, a significant crop shortage. The systematic use of balanced nutrients fertilizer systems, which primarily include complex, organo-mineral systems, helps to replenish humus reserves in soils, improve their phosphate and potassium regimes, which is accompanied by an increase in the productivity of cultivated crops and crop rotations in general. Organic (biological) fertilizer systems in the conditions of the Nonchernozem zone of Russia are inferior to organo-mineral ones in terms of crop productivity and do not have significant differences in the quality of plant products.

Liming and the application of organic fertilizers limit the entry into plants and the accumulation in commercial crops of a number of heavy metals, the mobility of which decreases when soils are neutralized and due to sorption by organic matter and the formation of organometallic complexes with it.

One of the methods for increasing soil fertility is the integrated agrochemical cultivation of fields, which was introduced into agriculture in the 80s of the last century. This method provides for in the shortest possible time, through the complex application of mineral and organic fertilizers, ameliorants and plant protection products, to increase soil fertility to the optimum level and ensure the planned yield of crops in crop rotation.

The use of mineral and organic fertilizers on the soils of the CCR replenishes the reserves of available forms of nitrogen, phosphorus and potassium, and increases crop yields. This is evidenced by numerous data obtained in research institutions.

Under the conditions of the chernozem type of soil formation, phosphorus always remains the limiting element in the formation of the productivity of grain crops, and under the conditions of gray forest soils, both phosphorus and potassium are such. This means that potassium is a limiting element not only for gray forest soils, but also for soddy-podzolic soils that form under more humid conditions.

The results of soil fertility monitoring carried out by the agrochemical service show a decrease in soil organic matter and basic nutrients, which negatively affects the productivity and economic efficiency of agricultural production. Currently, 31% of arable land has hyperacidity, 52% low humus content, 22%? lack of phosphorus and 9% ? lack of potassium.

The influence of mineral fertilizers on product quality and human health

Mineral fertilizers can have a negative impact both on plants and on the quality of plant products, as well as on the organisms that consume them. The main of these impacts 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 probability of plant lodging increases sharply.

Many fertilizers, especially chlorine-containing ones (ammonium chloride, potassium chloride), have a negative effect on animals and humans, mainly through water, where released chlorine enters.

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

Table 1

The impact 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 methods of application - accumulation in the form of nitrates (especially in vegetables), violent growth to the detriment of stability, increased morbidity, especially 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, increase plant resistance to diseases

At high doses, toxicosis of plants is possible. They act mainly through the heavy metals contained in them (cadmium, arsenic, selenium), radioactive elements and fluorine. The main accumulators are parsley, onion, sorrel.

Potash

Similar to phosphorus

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, greenhouse vegetables.

table 2

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

Types of fertilizers

Main Impacts

Nitrogen (nitrate forms)

Nitrates (maximum concentration limit for water 10 mg/l, for food - 500 mg/day per person) are reduced in the body to nitrites, which cause 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, loss of eyelashes, rupture of the alveoli. In animal husbandry: beriberi decrease in productivity, accumulation of urea in milk, increase in morbidity, decrease in fertility.

Phosphoric (superphosphate and fluorine, cadmium and other heavy metals contained in it)

Mainly through fluorine. Its excess in drinking water (more than 2 mg / l) causes damage to the enamel of teeth in humans, loss of elasticity of blood vessels. At a content of more than 8 mg / l - osteochondrosis phenomena.

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 object 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 subsequent generations.

Cultivated lands are the result of complex natural processes and the 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 harvest, a person removes a significant amount of mineral and organic substances from the soil, thereby uniting 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 rotations, 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 impact on 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, pollution with alien chemicals, salinization, waterlogging, and the removal of soils for various structures (transport highways, reservoirs, etc.). The damage caused to soils as a result of irrational use of land has assumed a threatening character. The decrease in the areas of fertile soils occurs many times faster than their formation. Erosion acceleration is especially dangerous for them.

Bibliography

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

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

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

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

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