Mineral fertilizers: benefits and harms. The influence of mineral and organic fertilizers and other methods of fertility mobilization on the agrochemical indicators of soils The negative impact of fertilizers on the soil
All mineral fertilizers, depending on the content of the main nutrients divided into phosphorus, nitrogen and potassium. In addition, complex mineral fertilizers containing a complex of nutrients are produced. The raw materials for obtaining the most common mineral fertilizers (superphosphate, saltpeter, sylvinite, nitrogen-fertilizer, etc.) are natural (apatite and phosphorite), potassium salts, mineral acids, ammonia, etc. Technological processes obtaining mineral fertilizers are diverse, more often they use the method of decomposition of phosphorus-containing raw materials with mineral acids.
The main factors in the production of mineral fertilizers are the high dust content of the air and its gas pollution. Dust and gases also contain its compounds, phosphoric acid, salts of nitric acid and other chemical compounds that are industrial poisons (see Industrial poisons).
Of all the substances that make up mineral fertilizers, the most toxic compounds are fluorine (see), (see) and nitrogen (see). Inhalation of dust containing mineral fertilizers leads to the development of catarrhs of the upper respiratory tract, laryngitis, bronchitis, (see). With prolonged contact with the dust of mineral fertilizers, chronic intoxication of the body is possible, mainly as a result of the influence of fluorine and its compounds (see). The group of nitrogen and complex mineral fertilizers can provide bad influence on the body in connection with methemoglobin formation (see Methemoglobinemia). Measures for the prevention and improvement of working conditions in the production of mineral fertilizers consist in sealing dusty processes, constructing a rational ventilation system (general and local), mechanization and automation of the most labor-intensive stages of production.
Measures of personal prevention are of great hygienic importance. All workers at enterprises for the production of mineral fertilizers must be provided with overalls. When working, accompanied by a large release of dust, overalls are used (GOST 6027-61 and GOST 6811 - 61). Dust removal and disposal of overalls is mandatory.
An important measure is the use of anti-dust respirators (Petal, U-2K, etc.) and goggles. To protect the skin, protective ointments should be used (IER-2, Chumakov, Selissky, etc.) and indifferent creams and ointments (silicone cream, lanolin, petroleum jelly, etc.). Personal prevention measures also include daily showering, thorough hand washing, and before meals.
Those working in the production of mineral fertilizers must at least twice a year undergo a mandatory x-ray examination of the skeletal system with the participation of a therapist, neuropathologist, otolaryngologist.
Mineral fertilizers - chemical substances introduced into the soil in order to obtain high and stable yields. Depending on the content of the main nutrients (nitrogen, phosphorus and potassium), they are divided into nitrogen, phosphorus and potash fertilizers.
Phosphates (apatites and phosphorites), potassium salts, mineral acids (sulphuric, nitric, phosphoric), nitrogen oxides, ammonia, etc. serve as raw materials for obtaining mineral fertilizers. agriculture is dust. The nature of the impact of this dust on the body, the degree of its danger depend on chemical composition fertilizers and their state of aggregation. Working with liquid mineral fertilizers (liquid ammonia, ammonia water, ammonia, etc.) is also associated with the release of harmful gases.
The toxic effect of dust of phosphate raw materials and the finished product depends on the type of mineral fertilizers and is determined by the fluorine compounds included in their composition (see) in the form of salts of hydrofluoric and fluorosilicic acids, phosphorus compounds (see) in the form of neutral salts of phosphoric acid, nitrogen compounds (see) in the form of salts of nitric and nitrous acids, silicon compounds (see) in the form of silicon dioxide in a bound state. The greatest danger is represented by fluorine compounds, which in different types phosphate raw materials and mineral fertilizers contain from 1.5 to 3.2%. Exposure to dust of phosphate raw materials and mineral fertilizers can cause catarrhs of the upper respiratory tract, rhinitis, laryngitis, bronchitis, pneumoconiosis, etc. in workers, mainly due to the irritating effect of dust. The local irritating effect of dust depends mainly on the presence of alkali metal salts in it. With prolonged contact with the dust of mineral fertilizers, chronic intoxication of the body is possible, mainly from exposure to fluorine compounds (see Fluorosis). Along with the fluorosogenic effect, the group of nitrogen and complex mineral fertilizers also has a methemoglobin-forming effect (see Methemoglobinemia), which is due to the presence of salts of nitric and nitrous acids in their composition.
In the production, transportation and use of mineral fertilizers in agriculture, precautions must be observed. In the production of mineral fertilizers, a system of anti-dust measures is carried out: a) sealing and aspiration of dusty equipment; b) dust-free cleaning of premises; c) dust removal of the air extracted by mechanical ventilation before its release into the atmosphere. The industry produces mineral fertilizers in granular form, in containers, bags, etc. This also prevents intensive dust formation during the application of fertilizers. To protect the respiratory system from dust, respirators are used (see), overalls (see Clothing, Glasses). It is advisable to use protective ointments, crusts (Selissky, IER-2, Chumakov, etc.) and indifferent creams (lanolin, vaseline, etc.), which protect the skin of workers. It is recommended not to smoke while working, rinse your mouth thoroughly before eating and drinking water. Take a shower after work. There should be enough vitamins in the diet.
Employees must undergo a medical examination at least twice a year with mandatory x-rays of the skeletal system and chest.
The use of mineral fertilizers (even in high doses) does not always lead to the predicted increase in yield.
Numerous studies indicate that the weather conditions of the growing season have such a strong influence on the development of plants that extremely unfavorable weather conditions actually neutralize the effect of increasing yields even at high doses of nutrients (Strapenyants et al., 1980; Fedoseev, 1985). The coefficients of use of nutrients from mineral fertilizers can differ sharply depending on the weather conditions of the growing season, decreasing for all crops in years with insufficient moisture (Yurkin et al., 1978; Derzhavin, 1992). In this regard, any new methods to improve the efficiency of mineral fertilizers in areas of unsustainable agriculture deserve attention.
One of the ways to increase the efficiency of the use of nutrients from fertilizers and soil, strengthen plant immunity to adverse environmental factors and improve the quality of the products obtained is the use of humic preparations in the cultivation of crops.
Over the past 20 years, interest in humic substances used in agriculture has increased significantly. The topic of humic fertilizers is not new either for researchers or for agricultural practitioners. Since the 50s of the last century, the effect of humic preparations on the growth, development, and yield of various crops has been studied. Currently, due to a sharp rise in the price of mineral fertilizers, humic substances are widely used to increase the efficiency of the use of nutrients from the soil and fertilizers, increase plant immunity to adverse environmental factors and improve the quality of the crop of the products obtained.
Diverse raw materials for the production of humic preparations. These can be brown and dark coals, peat, lake and river sapropel, vermicompost, leonardite, as well as various organic fertilizers and waste.
The main method for obtaining humates today is the technology of high-temperature alkaline hydrolysis of raw materials, which results in the release of surface-active high-molecular organic substances of various masses, characterized by a certain spatial structure and physico-chemical properties. The preparative form of humic fertilizers can be a powder, paste or liquid with different specific gravity and concentration of the active substance.
The main difference for various humic preparations is the form of the active component of humic and fulvic acids and (or) their salts - in water-soluble, digestible or indigestible forms. The higher the content of organic acids in a humic preparation, the more valuable it is both for individual use and especially for obtaining complex fertilizers with humates.
There are various ways of using humic preparations in crop production: processing of seed material, foliar top dressing, introduction of aqueous solutions into the soil.
Humates can be used both separately and in combination with plant protection products, growth regulators, macro- and microelements. The range of their use in crop production is extremely wide and includes almost all agricultural crops produced both in large agricultural enterprises and in personal subsidiary plots. Recently, their use in various ornamental crops has grown significantly.
Humic substances have a complex effect that improves the condition of the soil and the system of interaction "soil - plants":
- increase the mobility of assimilable phosphorus in soil and soil solutions, inhibit immobilization of assimilable phosphorus and retrogradation of phosphorus;
- radically improve the balance of phosphorus in soils and phosphorus nutrition of plants, which is expressed in an increase in the proportion of organophosphorus compounds responsible for the transfer and transformation of energy, the synthesis of nucleic acids;
- improve soil structure, their gas permeability, water permeability of heavy soils;
- maintain the organo-mineral balance of soils, preventing their salinization, acidification and other negative processes leading to a decrease or loss of fertility;
- shorten the vegetative period by improving protein metabolism, concentrated delivery of nutrients to the fruit parts of plants, saturating them with high-energy compounds (sugars, nucleic acids, and other organic compounds), and also suppress the accumulation of nitrates in the green part of plants;
- enhance the development of the root system of the plant due to good nutrition and accelerated cell division.
Particularly important are beneficial features humic components to maintain the organo-mineral balance of soils with intensive technologies. In the article by Paul Fixen "The concept of increasing the productivity of crops and the efficiency of using nutrients by plants" (Fixen, 2010), a link is given to a systematic analysis of methods for assessing the efficiency of using nutrients by plants. As one of the significant factors affecting the efficiency of the use of nutrients, the intensity of crop cultivation technologies and the associated changes in the structure and composition of the soil, in particular, the immobilization of nutrients and the mineralization of organic matter, are indicated. Humic components in combination with key macronutrients, primarily phosphorus, maintain soil fertility under intensive technologies.
In the work of Ivanova S.E., Loginova I.V., Tyndall T. “Phosphorus: mechanisms of losses from the soil and ways to reduce them” (Ivanova et al., 2011), the chemical fixation of phosphorus in soils is noted as one of the main factors of a low degree the use of phosphorus by plants (at the level of 5 - 25% of the amount of phosphorus introduced in the 1st year). Increasing the degree of phosphorus use by plants in the year of application has a pronounced environmental effect - reducing the ingress of phosphorus with surface and underground runoff into water bodies. The combination of the organic component in the form of humic substances with the mineral in fertilizers prevents the chemical fixation of phosphorus into poorly soluble calcium, magnesium, iron and aluminum phosphates and retains phosphorus in a form available to plants.
In our opinion, the use of humic preparations in the composition of mineral macrofertilizers is very promising.
Currently, there are several ways to introduce humates into dry mineral fertilizers:
- surface treatment of granulated industrial fertilizers, which is widely used in the preparation of mechanical fertilizer mixtures;
- mechanical introduction of humates into powder with subsequent granulation in small-scale production of mineral fertilizers.
- introduction of humates into the melt during large-scale production of mineral fertilizers (industrial production).
The use of humic preparations for the production of liquid mineral fertilizers used for foliar treatment of crops has become very widespread in Russia and abroad.
The purpose of this publication is to show the comparative effectiveness of humated and conventional granular mineral fertilizers on grain crops (winter and spring wheat, barley) and spring rapeseed in various soil and climatic zones of Russia.
Sodium humate Sakhalin was chosen as a humic preparation to obtain guaranteed high results in terms of agrochemical efficiency with the following indicators ( tab. 1).
The production of Sakhalin humate is based on the use of brown coal from the Solntsevo deposit on Sakhalin, which have a very high concentration of humic acids in digestible form (more than 80%). Alkaline extract from brown coals of this deposit is almost completely soluble in water, non-hygroscopic and non-caking powder of dark brown color. Microelements and zeolites also pass into the composition of the product, which contribute to the accumulation of nutrients and regulate the metabolic process.
In addition to the indicated indicators of Sakhalin sodium humate, an important factor in its choice as a humic additive was the production of concentrated forms of humic preparations in industrial quantities, high agrochemical indicators of individual use, the content of humic substances mainly in water-soluble form and the presence of a liquid form of humate for uniform distribution in the granule in industrial production, as well as state registration as an agrochemical.
In 2004, Ammofos JSC in Cherepovets produced an experimental batch of a new type of fertilizer - azophoska (nitroammophoska) grade 13:19:19, with the addition of Sakhalin sodium humate (alkaline extract from leonardite) into the pulp according to technology, developed at OAO NIUIF. The quality indicators of humated ammophoska 13:19:19 are given in tab. 2.
The main task during industrial testing was to substantiate best way introduction of the Sakhalin humate additive while maintaining the water-soluble form of humates in the product. It is known that humic compounds in acidic environments (at pH<6) переходят в формы водорастворимых гуматов (H-гуматы) с потерей их эффективности.
The introduction of powdered humate "Sakhalinsky" into the recycle in the production of complex fertilizers ensured that the humate did not come into contact with an acidic medium in the liquid phase and its undesirable chemical transformations. This was confirmed by the subsequent analysis of finished fertilizers with humates. The introduction of humate actually at the final stage of the technological process determined the preservation of the achieved productivity of the technological system, the absence of return flows and additional emissions. There was also no deterioration in physicochemical complex fertilizers (caking, granule strength, dustiness) in the presence of a humic component. The hardware design of the humate injection unit also did not present any difficulties.
In 2004, CJSC "Set-Orel Invest" (Oryol region) conducted a production experiment with the introduction of humated ammophosphate for barley. The increase in barley yield on an area of 4532 hectares from the use of humated fertilizer compared to the standard ammophos grade 13:19:19 was 0.33 t/ha (11%), the protein content in the grain increased from 11 to 12.6% ( tab. 3), which gave the farm an additional profit of 924 rubles/ha.
In 2004, field experiments were conducted at the SFUE OPH "Orlovskoye" All-Russian Research Institute of Legumes and Cereals (Oryol Region) to study the effect of humated and conventional ammophoska (13:19:19) on the yield and quality of spring and winter wheat.
Experiment scheme:
- Control (no fertilizer)
N26 P38 K38 kg a.i./ha
N26 P38 K38 kg a.i./ha humated
N39 P57 K57 kg a.i./ha
N39 P57 K57 kg a.i./ha humated.
In the experiment with spring wheat (variety Smena), the maximum yield of 2.78 t/ha was also observed when an increased dose of humated fertilizer was applied. In the same variant, the highest content of protein and gluten in the grain was observed. As in the experiment with winter wheat, the application of humated fertilizer statistically significantly increased the yield and the content of protein and gluten in the grain compared to the application of the same dose of standard mineral fertilizer. The latter works not only as an individual component, but also improves the absorption of phosphorus and potassium by plants, reduces the loss of nitrogen in the nitrogen cycle of nutrition, and generally improves the exchange between soil, soil solutions and plants.
A significant improvement in the quality of the crop and winter and spring wheat indicates an increase in the efficiency of mineral nutrition of the production part of the plant.
According to the results of the action, the humate additive can be compared with the influence of microcomponents (boron, zinc, cobalt, copper, manganese, etc.). With a relatively small content (from tenths to 1%), humate additives and microelements provide almost the same increase in yield and quality of agricultural products. The work (Aristarkhov, 2010) studied the effect of microelements on the yield and quality of grain of cereals and legumes and showed an increase in protein and gluten on the example of winter wheat with the main application on various types of soil. The directed influence of microelements and humates on the productive part of crops is comparable in terms of the results obtained.
High agrochemical production results with minimal refinement of the instrumentation scheme for large-scale production of complex fertilizers, obtained from the use of humated ammophoska (13:19:19) with Sakhalin sodium humate, made it possible to expand the range of humated grades of complex fertilizers with the inclusion of nitrate-containing grades.
In 2010, OJSC Mineralnye Udobreniya (Rossosh, Voronezh Region) produced a batch of humated azophoska 16:16:16 (N:P 2 O 5:K 2 O) containing humate (alkaline extract from leonardite) - not less than 0.3% and moisture - not more than 0.7%.
Azofoska with humates was a light gray granular organomineral fertilizer, differing from the standard one only in the presence of humic substances in it, which gave a barely noticeable light gray tint to the new fertilizer. Azofoska with humates was recommended as an organomineral fertilizer for the main and “before sowing” application to the soil and for root dressings for all crops where conventional azofoska can be used.
In 2010 and 2011 On the experimental field of the State Scientific Institution Moscow Research Institute of Agriculture "Nemchinovka", studies were carried out with humated azophos produced by JSC "Mineral Fertilizers" in comparison with the standard one, as well as with potash fertilizers (potassium chloride) containing humic acids (KaliGum), in comparison with the traditional potash fertilizer KCl.
Field experiments were carried out according to the generally accepted methodology (Dospekhov, 1985) on the experimental field of the Moscow Research Institute of Agriculture "Nemchinovka".
A distinctive feature of the soils of the experimental plot is a high content of phosphorus (about 150-250 mg/kg), and an average content of potassium (80-120 mg/kg). This led to the abandonment of the main application of phosphate fertilizers. The soil is soddy-podzolic medium loamy. Agrochemical characteristics of the soil before laying the experiment: organic matter content - 3.7%, pHsol. -5.2, NH 4 - - traces, NO 3 - - 8 mg / kg, P 2 O 5 and K 2 O (according to Kirsanov) - 156 and 88 mg/kg, respectively, CaO - 1589 mg/kg, MgO - 474 mg/kg.
In the experiment with azofoska and rapeseed, the size of the experimental plot was 56 m 2 (14m x 4m), the repetition was four times. Pre-sowing tillage after the main fertilization - with a cultivator and immediately before sowing - with RBC (rotary harrow-cultivator). Sowing - with an Amazon seeder in optimal agrotechnical terms, seeding depth of 4-5 cm - for wheat and 1-3 cm - for rapeseed. Seeding rates: wheat - 200 kg/ha, rapeseed - 8 kg/ha.
In the experiment, spring wheat variety MIS and spring rapeseed variety Podmoskovny were used. The MIS variety is a highly productive mid-season variety that allows you to consistently obtain grain suitable for the production of pasta. The variety is resistant to lodging; much weaker than the standard is affected by brown rust, powdery mildew and hard smut.
Spring rapeseed Podmoskovny - mid-season, vegetation period 98 days. Ecologically plastic, characterized by uniform flowering and maturation, resistance to lodging 4.5-4.8 points. The low content of glucosinolates in the seeds allows the use of cake and meal in the diets of animals and poultry at higher rates.
The wheat crop was harvested in the phase of full grain ripeness. Rape was cut for green fodder in the flowering phase. Experiments for spring wheat and rapeseed were laid out according to the same scheme.
The analysis of soil and plants was carried out according to standard and generally accepted methods in agrochemistry.
Scheme of experiments with azofoska:
Background (50 kg a.i. N/ha for top dressing)
Background + azophoska main application 30 kg a.i. NPK/ha
Background + azophoska with humate main application 30 kg a.i. NPK/ha
Background + azophoska main application 60 kg a.i. NPK/ha
Background + azophoska with humate main application 60 kg a.i. NPK/ha
Background + azophoska main application 90 kg a.i. NPK/ha
Background + azophoska with humate main application 90 kg a.i. NPK/ha
During the years of research, the weather conditions differed significantly from the long-term average for the Non-Chernozem zone. In 2010, May and June were favorable for the development of agricultural crops, and generative organs were laid in plants with the prospect of a future grain yield of about 7 t/ha for spring wheat (as in 2009) and 3 t/ha for rapeseed. However, as in the entire Central region of the Russian Federation, a long drought was observed in the Moscow region from early July until the wheat harvest in early August. The average daily temperatures during this period were exceeded by 7 ° C, and daytime temperatures were above 35 ° C for a long time. Separate short-term precipitation fell in the form of heavy rains and water flowed down with surface runoff and evaporated, only partially absorbed into the soil. The saturation of the soil with moisture during short periods of rain did not exceed the penetration depth of 2-4 cm. In 2011, in the first ten days of May, after sowing and during plant germination, precipitation fell almost 4 times less (4 mm) than the weighted average long-term norm (15 mm).
The average daily air temperature during this period (13.9 o C) was significantly higher than the long-term average daily temperature (10.6 o C). The amount of precipitation and air temperature in the 2nd and 3rd decades of May did not differ significantly from the amount of average precipitation and average daily temperatures.
In June, the precipitation was much less than the average long-term norm, the air temperature exceeded the average daily by 2-4 o C.
July was hot and dry. In total, during the growing season, precipitation was 60 mm less than the norm, and the average daily air temperature was about 2 o C higher than the long-term average. Unfavorable weather conditions in 2010 and 2011 could not but affect the state of crops. The drought coincided with the grain filling phase of wheat, which ultimately led to a significant reduction in yield.
Prolonged air and soil drought in 2010 did not give the expected effect from increasing doses of azofoska. This has been shown in both wheat and rapeseed.
Moisture deficiency turned out to be the main obstacle in the implementation of the soil fertility, while the wheat yield as a whole was two times lower than in a similar experiment in 2009 (Garmash et al., 2011). Yield increases when applying 200, 400 and 600 kg/ha of azofoska (physical weight) were almost the same ( tab. 5).
The low yield of wheat is mainly due to the frailty of the grain. The mass of 1000 grains in all variants of the experiment was 27–28 grams. Data on the structure of the yield on the variants did not differ significantly. In the mass of the sheaf, the grain was about 30% (under normal weather conditions, this figure is up to 50%). The tillering coefficient is 1.1-1.2. The mass of grain in an ear was 0.7-0.8 grams.
At the same time, in the variants of the experiment with humated azofoska, a significant yield increase was obtained with an increase in fertilizer doses. This is due, first of all, to the better general condition of plants and the development of a more powerful root system when using humates against the background of the general stress of crops from long and prolonged drought.
A significant effect from the use of humated azofoska was manifested at the initial stage of development of rapeseed plants. After sowing rapeseed seeds, as a result of a short rainstorm followed by high air temperatures, a dense crust formed on the soil surface. Therefore, seedlings on the variants with the introduction of conventional azophoska were uneven and very sparse compared to the variants with humated azophoska, which led to significant differences in the yield of green mass ( tab. 6).
In the experiment with potash fertilizers, the area of the experimental plot was 225 m 2 (15 m x 15 m), the experiment was repeated four times, the location of the plots was randomized. The area of the experiment is 3600 m 2 . The experiment was carried out in the link of crop rotation winter cereals - spring cereals - busy fallow. The predecessor of spring wheat is winter triticale.
Fertilizers were applied manually at the rate of: nitrogen - 60, potassium - 120 kg of a.i. per ha. Ammonium nitrate was used as nitrogen fertilizers, and potassium chloride and the new KaliGum fertilizer were used as potash fertilizers. In the experiment, spring wheat variety Zlata, recommended for cultivation in the Central region, was grown. The variety is early maturing with a productivity potential of up to 6.5 t/ha. Resistant to lodging, much weaker than the standard variety is affected by leaf rust and powdery mildew, at the level of the standard variety - by septoria. Before sowing, the seeds were treated with the Vincit disinfectant in the norms recommended by the manufacturer. In the tillering phase, wheat crops were fertilized with ammonium nitrate at the rate of 30 kg of a.i. per 1 ha.
Scheme of experiments with potash fertilizers:
- Control (no fertilizer).
N60 basic + N30 top dressing
N60 basic + N30 top dressing + K 120 (KCl)
N60 basic + N30 top dressing + K 120 (KaliGum)
Thus, field experiments have reliably proven the agrochemical effectiveness of complex fertilizers with humate additives, determined by the increase in yield and protein content in grain crops. To ensure these results, it is necessary to correctly select a humic preparation with a high proportion of water-soluble humates, its form and place of introduction into the technological process at the final stages. This makes it possible to achieve a relatively low content of humates (0.2 - 0.5% wt.) in humated fertilizers and to ensure a uniform distribution of humates over the granule. At the same time, an important factor is the preservation of a high proportion of the water-soluble form of humates in humated fertilizers.
Complex fertilizers with humates increase the resistance of agricultural crops to adverse weather and climatic conditions, in particular, to drought and deterioration of soil structure. They can be recommended as effective agrochemicals in areas of risky farming, as well as when using intensive farming methods with several crops per year to maintain high soil fertility, in particular, in expanding zones with a water deficit and arid zones. The high agrochemical efficiency of the humated ammophoska (13:19:19) is determined by the complex action of the mineral and organic parts with an increase in the action of nutrients, primarily phosphorus nutrition of plants, an improvement in the metabolism between soil and plants, and an increase in plant stress resistance.
Levin Boris Vladimirovich – candidate of technical sciences, deputy general. Director, Director for Technical Policy of PhosAgro-Cherepovets JSC; e-mail:[email protected] .
Ozerov Sergey Alexandrovich - Head of Market Analysis and Sales Planning Department of PhosAgro-Cherepovets JSC; e-mail:[email protected] .
Garmash Grigory Alexandrovich - Head of the Laboratory of Analytical Research of the Federal State Budgetary Scientific Institution "Moscow Research Institute of Agriculture" Nemchinovka ", Candidate of Biological Sciences; e-mail:[email protected] .
Garmash Nina Yuryevna - Scientific Secretary of the Moscow Research Institute of Agriculture "Nemchinovka", Doctor of Biological Sciences; e-mail:[email protected] .
Latina Natalya Valerievna - General Director of Biomir 2000 LLC, Production Director of the Sakhalin Humat Group of Companies; e-mail:[email protected] .
Literature
Paul I. Fixsen The concept of increasing the productivity of agricultural crops and the efficiency of the use of nutrients by plants // Plant Nutrition: Bulletin of the International Institute of Plant Nutrition, 2010, No. 1. - With. 2-7.
Ivanova S.E., Loginova I.V., Tundell T. Phosphorus: mechanisms of losses from the soil and ways to reduce them // Plant Nutrition: Bulletin of the International Institute of Plant Nutrition, 2011, No. 2. - With. 9-12.
Aristarkhov A.N. et al. The effect of microfertilizers on productivity, protein harvest and product quality of grain and leguminous crops // Agrochemistry, 2010, No. 2. - With. 36-49.
Strapenyants R.A., Novikov A.I., Strebkov I.M., Shapiro L.Z., Kirikoy Ya.T. Modeling of the regularities of the action of mineral fertilizers on the crop. Vestnik s.-kh. Nauki, 1980, No. 12. - p. 34-43.
Fedoseev A.P. Weather and fertilizer efficiency. Leningrad: Gidrometizdat, 1985. - 144 p.
Yurkin S.N., Pimenov E.A., Makarov N.B. Influence of soil and climatic conditions and fertilizers on the consumption of the main nutrients in the wheat crop // Agrochemistry, 1978, No. 8. - P. 150-158.
Derzhavin L.M. The use of mineral fertilizers in intensive agriculture. M.: Kolos, 1992. - 271 p.
Garmash N.Yu., Garmash G.A., Berestov A.V., Morozova G.B. Trace elements in intensive technologies for the production of grain crops // Agrochemical Bulletin, 2011, No. 5. - P. 14-16.
Municipal budgetary educational institution "Secondary school named after Dmitry Batiev" with. Gam Ust - Vymsky District Komi Republic
The work was completed by: Isakova Irina, student
Head: , teacher of biology and chemistry
Introduction………………………………………………..………………………………………3
I. Main part………………………………………………………………….….….…..4
Classification of mineral fertilizers…………………………………………..….....4
II. Practical part….…………………………………………….……………..............6
2.1 Growing plants at different concentrations of minerals… ..….6
Conclusion…………………………………….…………………………………………....9
List of literature used………………………………………….…………….10
Introduction
Relevance of the problem
Plants absorb minerals from the soil along with water. In nature, these substances then return to the soil in one form or another after the death of the plant or its parts (for example, after leaf fall). Thus, there is a circulation of minerals. However, such a return does not occur, since minerals are carried away from the fields during harvesting. To avoid soil depletion, people make various fertilizers in the fields, gardens and orchards. Fertilizers improve soil nutrition of plants, improve soil properties. As a result, the yield increases.
The aim of the work is: to study the effects of mineral fertilizers on the growth and development of plants.
- To study the classification of mineral fertilizers. Experimentally determine the degree of influence of potash and phosphorus fertilizers on the growth and development of plants. Design a booklet "Recommendations for gardeners"
Practical significance:
Vegetables play a very important role in human nutrition. A fairly large number of gardeners grow vegetables on their plots. Your garden plot helps to save some, and also makes it possible to grow organic products. Therefore, the results of the study can be used when working in the country and the garden.
Research methods: study and analysis of literature; conducting experiments; comparison.
Literature review. When writing the main part of the project, sites were used, the site "Secret of the cottage", the site "Wikipedia" and others. The practical part is based on the work, "Simple Experiments in Botany".
1 Main body
Classification of mineral fertilizers
Fertilizers are substances used to improve plant nutrition, soil properties, and increase yields. Their effect is due to the fact that these substances provide plants with one or more deficient chemical components necessary for their normal growth and development. Fertilizers are divided into mineral and organic.
Mineral fertilizers - extracted from the bowels or industrially obtained chemical compounds, contain the main nutrients (nitrogen, phosphorus, potassium) and microelements important for life. They are made in special factories, they contain nutrients in the form of mineral salts. Mineral fertilizers are divided into simple (one-component) and complex. Simple mineral fertilizers contain only one of the main nutrients. These include nitrogen, phosphorus, potash fertilizers and microfertilizers. Complex fertilizers contain at least two main nutrients. In turn, complex mineral fertilizers are divided into complex, complex-mixed and mixed.
Nitrogen fertilizers.
Nitrogen fertilizers enhance the growth of roots, bulbs and tubers. In fruit trees and berry bushes, nitrogen fertilizers not only increase the yield, but also improve the quality of the fruit. Nitrogen fertilizers are applied in early spring in any form. The deadline for applying nitrogen fertilizers is mid-July. This is due to the fact that fertilizers stimulate the growth of the aerial part, the leaf apparatus. If they are introduced in the second half of summer, then the plant will not have time to acquire the necessary winter hardiness, and will freeze in winter. Excess nitrogen fertilizer worsens survival.
Phosphorus fertilizers.
Phosphate fertilizers stimulate the development of the root system of plants. Phosphorus enhances the ability of cells to retain water and thus increases the resistance of plants against drought and low temperatures. With sufficient nutrition, phosphorus accelerates the transition of plants from the vegetative phase to fruiting. Phosphorus has a positive effect on the quality of fruits - it contributes to an increase in sugar, fats, and proteins in them. Phosphorus fertilizers can be applied every 3-4 years.
potassium fertilizers.
Potash fertilizers are responsible for the strength of shoots and trunks, therefore they are especially relevant for shrubs and trees. Potassium has a positive effect on the intensity of photosynthesis. If there is enough potassium in plants, then their resistance to various diseases increases. Potassium also promotes the development of mechanical elements of vascular bundles and bast fibers. With a lack of potassium, development is delayed. Potash fertilizers are applied under plants starting from the second half of summer.
2. Practical part
2.1 Growing plants at different concentrations of minerals
To complete the practical part, you will need: bean sprouts, in the phase of the first true leaf; three pots filled with sand; pipette; three solutions of nutrient salts containing potassium, nitrogen and phosphorus.
The amount of nutrients in fertilizers was calculated. Solutions of optimal concentrations were prepared. These solutions were used to feed the plants and monitor the growth and development of plants.
Preparation of nutrient solutions.
*Water for preparing the solution is hot
2 bean sprouts were planted in pots with moistened sand. A week later, one, the best plant, was left in each jar. On the same day, solutions of mineral salts prepared in advance were added to the sand.
During the experiment, the optimum air temperature and normal sand were maintained. Three weeks later, the plants were compared with each other.
Experience results.
Description of plants | plant height | number of leaves |
|
Pot number 1 "No salt" | The leaves are pale, dull green, starting to turn yellow. The tips and edges of the leaves turn brown, small rusty spots appear on the leaf blade. The sheet size is slightly smaller than other samples. The stem is thin, inclined, slightly branched. | ||
Pot number 2 "Less salt" | The leaves are pale green. Leaves are medium to large. There are no visible damage. The stem is thick and branched. | ||
Pot #3 "More Salts" | The leaves are bright green and large. The plant looks healthy. The stem is thick and branched. |
Based on the experimental results, the following conclusions can be drawn:
- For normal growth and development of plants, minerals are necessary (development of beans in pots No. 2 and No. 3). They can be absorbed only in dissolved form. The full development of plants occurs with the use of complex fertilizers (nitrogen, phosphorus, potash). The amount of fertilizer applied must be strictly dosed.
As a result of the experience and the study of literature, some rules for the use of fertilizers have been drawn up:
Organic fertilizers cannot fully satisfy the plants with nutrients, therefore mineral fertilizers are also added. In order not to harm plants and soil, it is necessary to have an elementary understanding of the consumption of nutrients and mineral fertilizers by plants. When using mineral fertilizers, the following must be remembered:
- do not exceed the recommended doses and apply only in those phases of plant growth and development, when necessary; avoid getting fertilizer on the leaves; conduct liquid top dressing after watering, otherwise you can burn the roots; stop any fertilizing four to ten weeks before harvest to avoid the accumulation of nitrates.
Conclusion
The use of mineral fertilizers is one of the main methods of intensive farming. With the help of fertilizers, you can dramatically increase the yields of any crop. Mineral salts are of great importance for the growth and development of plants. Plants look healthy.
Thanks to experience, it became clear that regular fertilization of plants with fertilizers should become a common procedure, since many violations in the development of plants are caused precisely by improper care associated with a lack of nutrition, which happened in our case.
There are many important things for plants. One of them is the soil, it also needs to be selected correctly for each specific plant. Apply fertilizers in accordance with the appearance and physiological state of the plants.
Organic and mineral fertilizers have a huge impact on the soil. In fact, such agrotechnical function as soil fertilization is a more intense imitation of complex natural processes occurring in an ecosystem over long periods.
Man is changing the natural principles of interaction between plants, animals and soil, adapting technologies to the most effective results when growing crops.
The effect of fertilizers on the soil can be different - both positive and negative. In order not to harm the soil, plants and beneficial microorganisms, it is necessary to comply with agrotechnical and environmental standards developed for various agricultural types of fertilizers.
The most useful for the soil are natural fertilizers. First of all, it is freshwater silt. It can be applied in its pure form or diluted with compost, or mixed with other types of fertilizers.
Acidophilic crops prefer acidic soil. How can you change the pH of the soil to the acidic side? For this purpose, such a type of natural fertilizer as needles is well suited. The introduction of needles into the ground can give a good effect for acidophilic plants, but will negatively affect other species that require a neutral or alkaline soil environment to grow.Many fruit trees (primarily apples and pears) need iron during the ripening period. Thus, the treatment of fruit trees with iron sulphate will help to provide them with iron, which will favorably affect the yield, size and bright color of the fruit.
Nitrogen fertilizers should be applied to the soil with care. The fact is that as a result of the accumulation of nitrate salts (nitrates) in the soil, many agricultural crops accumulate nitrates in themselves and become poisonous to humans and animals. This is especially true for melon crops.
The use of iodine fertilizers for top dressing outside the root system gives a good effect on vegetable crops and fruit and berry plants (adds up to 40% yield).
Some plants prefer alkaline soil. In addition, a situation often arises when plants and soil are significantly polluted by vehicle exhausts and other industrial waste.
This leads to the accumulation of heavy metals in the soil, which, with a high degree of probability, leads to diseases in humans and animals. Lime or ash can be used to neutralize heavy metals and change the pH of the soil to alkaline. Alkali binds heavy metals, turning them into salts.
There are other types of fertilizers that allow you to change the structure, acidity, fertility, salinity and other soil indicators. The main thing is that when using fertilizers, agrotechnical and environmental standards are not violated.
Kuban State University
Department of Biology
in the discipline "Soil Ecology"
"The hidden negative effect of fertilizers".
Performed
Afanasyeva L. Yu.
5th year student
(speciality -
"Bioecology")
Checked Bukareva O.V.
Krasnodar, 2010
Introduction…………………………………………………………………………………...3
1. The effect of mineral fertilizers on soils……………………………………...4
2. The effect of mineral fertilizers on atmospheric air and water…………..5
3. The influence of mineral fertilizers on product quality and human health…………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………
4. Geoecological consequences of the use of fertilizers……………………...8
5. The impact of fertilizers on the environment……………………………..10
Conclusion………………………………………………………………………………….17
List of used literature…………………………………………………...18
Introduction
Pollution of soils with foreign chemicals causes great damage to them. A significant factor in environmental pollution is the chemicalization of agriculture. Even mineral fertilizers, if used incorrectly, can cause environmental damage with a dubious economic effect.
Numerous studies of agricultural chemists have shown that different types and forms of mineral fertilizers affect soil properties in different ways. Fertilizers introduced into the soil enter into complex interactions with it. All sorts of transformations take place here, which depend on a number of factors: the properties of fertilizers and soil, weather conditions, and agricultural technology. From how the transformation of certain types of mineral fertilizers (phosphorus, potash, nitrogen) occurs, their influence on soil fertility depends.
Mineral fertilizers are an inevitable consequence of intensive farming. There are calculations that in order to achieve the desired effect from the use of mineral fertilizers, their world consumption should be about 90 kg / year per person. The total production of fertilizers in this case reaches 450-500 million tons/year, while at present their world production is 200-220 million tons/year or 35-40 kg/year per person.
The use of fertilizers can be considered as one of the manifestations of the law of increasing energy input per unit of agricultural output. This means that in order to obtain the same increase in yield, an increasing amount of mineral fertilizers is required. So, at the initial stages of fertilizer application, an increase of 1 ton of grain per 1 ha ensures the introduction of 180-200 kg of nitrogen fertilizers. The next additional ton of grain is associated with a dose of fertilizer 2-3 times greater.
Environmental consequences of the use of mineral fertilizers It is advisable to consider, at least from three points of view:
Local impact of fertilizers on ecosystems and soils to which they are applied.
Outrageous impact on other ecosystems and their links, primarily on the aquatic environment and atmosphere.
Impact on the quality of products obtained from fertilized soils and human health.
1. Effect of mineral fertilizers on soils
In the soil as a system, such changes that lead to loss of fertility:
Increases acidity;
The species composition of soil organisms is changing;
The circulation of substances is disturbed;
The structure that worsens other properties is destroyed.
There is evidence (Mineev, 1964) that an increased leaching of calcium and magnesium from them is a consequence of an increase in soil acidity with the use of fertilizers (primarily acidic nitrogen fertilizers). To neutralize this phenomenon, these elements have to be introduced into the soil.
Phosphorus fertilizers do not have such a pronounced acidifying effect as nitrogen fertilizers, but they can cause zinc starvation of plants and the accumulation of strontium in the resulting products.
Many fertilizers contain foreign impurities. In particular, their introduction can increase the radioactive background and lead to progressive accumulation of heavy metals. Basic way reduce these effects.– moderate and scientifically based use of fertilizers:
Optimal doses;
The minimum amount of harmful impurities;
Alternate with organic fertilizers.
You should also remember the expression that "mineral fertilizers are a means of masking realities." Thus, there is evidence that more minerals are removed with the products of soil erosion than they are introduced with fertilizers.
2. Effect of mineral fertilizers on atmospheric air and water
The influence of mineral fertilizers on atmospheric air and water is mainly associated with their nitrogen forms. Nitrogen from mineral fertilizers enters the air either in free form (as a result of denitrification) or in the form of volatile compounds (for example, in the form of nitrous oxide N2O).
According to modern concepts, gaseous losses of nitrogen from nitrogen fertilizers range from 10 to 50% of its application. An effective means of reducing gaseous losses of nitrogen is their scientifically substantiated application:
Application to the root-forming zone for the fastest absorption by plants;
The use of substances-inhibitors of gaseous losses (nitropyrin).
The most tangible impact on water sources, in addition to nitrogen, is phosphorus fertilizers. Carryover of fertilizers into water sources is minimized when applied correctly. In particular, it is unacceptable to spread fertilizers on the snow cover, disperse them from aircraft near water bodies, and store them in the open.
3. 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 diseases 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
Types of fertilizers | The influence of mineral fertilizers |
|
positive | negative |
|
At high doses or untimely methods of application - accumulation in the form of nitrates, violent growth to the detriment of stability, increased morbidity, especially fungal diseases. Ammonium chloride contributes to the accumulation of Cl. The main accumulators of nitrates are vegetables, corn, oats, and tobacco. |
||
Phosphoric | Reduce the negative effects of nitrogen; improve product quality; help to increase the resistance of plants 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. | They act 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
Types of fertilizers | Main Impacts |
| 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, reduced productivity, accumulation of urea in milk, increased morbidity, reduced fertility. |
Phosphoric Superphosphate | They act 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. |
| Potassium chloride Ammonium chloride | Consumption of water with a chlorine content of more than 50 mg/l causes poisoning (toxicosis) in humans and animals. |
4. Geoecological consequences of fertilizer application
For their development, plants need a certain amount of nutrients (compounds of nitrogen, phosphorus, potassium), usually absorbed from the soil. In natural ecosystems, nutrients assimilated by vegetation return to the soil as a result of degradation processes in the cycle of matter (decomposition of fruits, plant litter, dead shoots, roots). A certain amount of nitrogen compounds is fixed by bacteria from the atmosphere. Part of the biogens is introduced with precipitation. On the negative side of the balance are infiltration and surface runoff of soluble compounds of biogens, their removal with soil particles in the process of soil erosion, as well as the transformation of nitrogen compounds into a gaseous phase with its release into the atmosphere.
In natural ecosystems, the rate of accumulation or consumption of nutrients is usually low. For example, for the virgin steppe on the chernozems of the Russian Plain, the ratio between the flow of nitrogen compounds through the boundaries of the selected area of the steppe and its reserves in the upper meter layer is about 0.0001% or 0.01%.
Agriculture violates the natural, almost closed balance of nutrients. The annual harvest takes away some of the nutrients contained in the produced product. In agroecosystems, the rate of nutrient removal is 1-3 orders of magnitude higher than in natural systems, and the higher the yield, the relatively greater the intensity of removal. Therefore, even if the initial supply of nutrients in the soil was significant, it can be used up relatively quickly in the agroecosystem.
In total, with the grain harvest in the world, for example, about 40 million tons of nitrogen are removed per year, or approximately 63 kg per 1 ha of grain area. This implies the need to use fertilizers to maintain soil fertility and increase yields, since with intensive farming without fertilizers, soil fertility decreases already in the second year. Nitrogen, phosphorus and potash fertilizers are usually used in various forms and combinations, depending on local conditions. At the same time, the use of fertilizers masks soil degradation by replacing natural fertility with fertility based mainly on chemicals.
The production and consumption of fertilizers in the world has grown steadily, increasing over 1950-1990. about 10 times. The average world use of fertilizers in 1993 was 83 kg per 1 ha of arable land. Behind this average is a large difference in the consumption of different countries. The Netherlands uses the most fertilizers, and there the level of fertilizer application has even decreased in recent years: from 820 kg/ha to 560 kg/ha. On the other hand, average fertilizer consumption in Africa in 1993 was only 21 kg/ha, with 24 countries using 5 kg/ha or less.
Along with the positive effects, fertilizers also create environmental problems, especially in countries with a high level of their use.
Nitrates are hazardous to human health if their concentration in drinking water or agricultural products is higher than the established MPC. The concentration of nitrates in water flowing from fields is usually between 1 and 10 mg/l, and from unploughed land it is an order of magnitude lower. As the mass and duration of fertilizer use increases, more and more nitrates enter surface and groundwater, making them undrinkable. If the level of application of nitrogen fertilizers does not exceed 150 kg/ha per year, then approximately 10% of the volume of applied fertilizers gets into natural waters. At a higher load, this proportion is even higher.
In particular, the problem of groundwater pollution after nitrates have entered the aquifer is serious. Water erosion, carrying away soil particles, also transfers the compounds of phosphorus and nitrogen contained in them and adsorbed on them. If they enter water bodies with slow water exchange, the conditions for the development of the eutrophication process improve. So, in the rivers of the United States, dissolved and suspended compounds of biogens have become the main water pollutant.
The dependence of agriculture on mineral fertilizers has led to major shifts in the global cycles of nitrogen and phosphorus. The industrial production of nitrogen fertilizers has led to a disruption in the global nitrogen balance due to an increase in the amount of nitrogen compounds available to plants by 70% compared to the pre-industrial period. Too much nitrogen can change soil acidity as well as soil organic matter content, which can further leach soil nutrients and degrade natural water quality.
According to scientists, the washout of phosphorus from the slopes in the process of soil erosion is at least 50 million tons per year. This figure is comparable to the annual industrial production of phosphate fertilizers. In 1990, as much phosphorus was carried by rivers into the ocean as was applied to the fields, namely 33 million tons. Since gaseous phosphorus compounds do not exist, it moves under the influence of gravity, mainly with water, mainly from continents to oceans . This leads to a chronic lack of phosphorus on land and to another global geoecological crisis.
5. Environmental impact of fertilizers
The negative effect of fertilizers on the environment is primarily due to the imperfection of the properties and chemical composition of fertilizers. significant disadvantages of many mineral fertilizers are:
The presence of residual acid (free acidity) due to the technology of their production.
Physiological acidity and alkalinity resulting from the predominant use of cations or anions by plants from fertilizers. Long-term use of physiologically acidic or alkaline fertilizers changes the reaction of the soil solution, leads to humus losses, increases the mobility and migration of many elements.
High solubility of fats. In fertilizers, unlike natural phosphate ores, fluorine is in the form of soluble compounds and easily enters the plant. The increased accumulation of fluorine in plants disrupts metabolism, enzymatic activity (inhibits the action of phosphatase), negatively affects protein photo- and biosynthesis, and fruit development. High doses of fluorine inhibit the development of animals and lead to poisoning.
The presence of heavy metals (cadmium, lead, nickel). Phosphoric and complex fertilizers are the most contaminated with heavy metals. This is due to the fact that almost all phosphorus ores contain large amounts of strontium, rare earth and radioactive elements. The expansion of production and the use of phosphate and complex fertilizers leads to environmental pollution with fluorine and arsenic compounds.
With the existing acid methods of processing natural phosphate raw materials, the degree of utilization of fluorine compounds in the production of superphosphate does not exceed 20-50%, in the production of complex fertilizers - even less. The content of fluorine in superphosphate reaches 1-1.5, in ammophos 3-5%. On average, with each ton of phosphorus necessary for plants, about 160 kg of fluorine enters the fields.
However, it is important to understand that it is not the mineral fertilizers themselves, as sources of nutrients, that pollute the environment, but their associated components.
Soluble applied to the soil phosphate fertilizers are largely absorbed by the soil and become inaccessible to plants and do not move along the soil profile. It has been established that the first crop uses only 10-30% of P2O5 from phosphate fertilizers, and the rest remains in the soil and undergoes all kinds of transformations. For example, in acidic soils, the phosphorus of superphosphate is mostly converted into iron and aluminum phosphates, and in chernozem and all carbonate soils, into insoluble calcium phosphates. The systematic and long-term use of phosphorus fertilizers is accompanied by the gradual cultivation of soils.
It is known that long-term use of large doses of phosphate fertilizers can lead to the so-called "phosphating", when the soil is enriched with assimilable phosphates and new portions of fertilizers have no effect. In this case, an excess of phosphorus in the soil can upset the ratio between nutrients and sometimes reduce the availability of zinc and iron to plants. Thus, in the conditions of the Krasnodar Territory on ordinary carbonate chernozems with the usual application of P2O5, corn unexpectedly sharply reduced the yield. We had to find ways to optimize the elemental nutrition of plants. Soil phosphating is a certain stage of their cultivation. This is the result of the inevitable accumulation of "residual" phosphorus, when fertilizers are applied in an amount that exceeds the carry-over of phosphorus with the crop.
As a rule, this “residual” phosphorus in the fertilizer is more mobile and available to plants than natural soil phosphates. With the systematic and long-term application of these fertilizers, it is necessary to change the ratios between nutrients, taking into account their residual effect: the dose of phosphorus should be reduced, and the dose of nitrogen fertilizers should be increased.
Potassium fertilizer, introduced into the soil, like phosphorus, does not remain unchanged. Part of it is in the soil solution, part goes into an absorbed-exchange state, and part turns into a non-exchange, inaccessible form for plants. The accumulation of available forms of potassium in the soil, as well as the transformation into an inaccessible state as a result of long-term use of potassium fertilizers, depends mainly on soil properties and weather conditions. So, in chernozem soils, although the amount of assimilated forms of potassium under the influence of fertilizer increases, but to a lesser extent than on soddy-podzolic soils, since in chernozem fertilizer potassium is more converted into a non-exchangeable form. In a zone with a large amount of precipitation and during irrigated agriculture, potassium fertilizers may be washed out of the root layer of the soil.
In areas with insufficient moisture, in hot climates, where soils are periodically moistened and dry out, intensive processes of potassium fixation of fertilizers by the soil are observed. Under the influence of fixation, potassium of fertilizers passes into a non-exchangeable, inaccessible state for plants. Of great importance on the degree of potassium fixation by soils is the type of soil minerals, the presence of minerals with a high fixing ability. These are clay minerals. Chernozems have a greater ability to fix potassium fertilizers than soddy-podzolic soils.
Alkalization of the soil, caused by the application of lime or natural carbonates, especially soda, increases fixation. Potassium fixation depends on the dose of fertilizer: with an increase in the dose of applied fertilizers, the percentage of potassium fixation decreases. In order to reduce the fixation of potassium fertilizers by soils, it is recommended to apply potash fertilizers to a sufficient depth to prevent drying out and apply them more often in crop rotation, since soils that were systematically fertilized with potassium fix it weaker when it is added again. But the fixed potassium of fertilizers, which is in a non-exchange state, also participates in plant nutrition, since over time it can turn into an exchange-absorbed state.
nitrogen fertilizers on interaction with the soil significantly differ from phosphorus and potash. Nitrate forms of nitrogen are not absorbed by the soil, so they can easily be washed out by precipitation and irrigation water.
Ammonia forms of nitrogen are absorbed by the soil, but after their nitrification they acquire the properties of nitrate fertilizers. Partially, ammonia can be absorbed by the soil without exchange. Non-exchangeable, fixed ammonium is available to plants to a small extent. In addition, the loss of fertilizer nitrogen from the soil is possible as a result of volatilization of nitrogen in free form or in the form of nitrogen oxides. When nitrogen fertilizers are applied, the content of nitrates in the soil changes dramatically, since the compounds most easily absorbed by plants come with fertilizers. The dynamics of nitrates in the soil to a greater extent characterizes its fertility.
A very important property of nitrogen fertilizers, especially ammonia, is their ability to mobilize soil reserves, which is of great importance in the zone of chernozem soils. Under the influence of nitrogen fertilizers, soil organic compounds are more quickly mineralized and converted into forms that are easily accessible to plants.
Some nutrients, especially nitrogen in the form of nitrates, chlorides and sulfates, can enter groundwater and rivers. The consequence of this is the excess of the norms of the content of these substances in the water of wells, springs, which can be harmful to people and animals, and also leads to an undesirable change in hydrobiocenoses and damages the fish industry. The migration of nutrients from soils to groundwater in different soil and climatic conditions is not the same. In addition, it depends on the types, forms, doses and terms of fertilizers used.
In the soils of the Krasnodar Territory with a periodically leaching water regime, nitrates are found to a depth of 10 m or more and merge with groundwater. This indicates a periodic deep migration of nitrates and their inclusion in the biochemical cycle, the initial links of which are soil, parent rock, and groundwater. Such migration of nitrates can be observed in wet years, when soils are characterized by a leaching water regime. It is during these years that the danger of nitrate pollution of the environment arises when large doses of nitrogen fertilizers are applied before winter. In years with a non-leaching water regime, the entry of nitrates into groundwater completely stops, although residual traces of nitrogen compounds are observed along the entire profile of the parent rock to groundwater. Their preservation is facilitated by the low biological activity of this part of the weathering crust.
In soils with a non-leaching water regime (southern chernozems, chestnut soils), pollution of the biosphere with nitrates is excluded. They remain closed in the soil profile and are fully included in the biological cycle.
The harmful potential impact of nitrogen applied with fertilizers can be minimized by maximizing the use of nitrogen by crops. So, care must be taken that with an increase in the doses of nitrogen fertilizers, the efficiency of using their nitrogen by plants increases; there was not a large amount of nitrates unused by plants, which are not retained by soils and can be washed out by precipitation from the root layer.
Plants tend to accumulate in their bodies nitrates contained in the soil in excess quantities. The yield of plants is growing, but the products are poisoned. Vegetable crops, watermelons and melons accumulate nitrates especially intensively.
In Russia, MPCs for nitrates of plant origin have been adopted (Table 3). The permissible daily dose (ADD) for a person is 5 mg per 1 kg of body weight.
Table 3 - Permissible levels of nitrate content in products
vegetable origin, mg/kg
Product | Priming |
|
open | protected |
|
Potato | ||
White cabbage | ||
Beetroot | ||
Leafy vegetables (lettuce, spinach, sorrel, cilantro, lettuce, parsley, celery, dill) | ||
Sweet pepper | ||
table grapes | ||
Baby food (canned vegetables) | ||
Nitrates themselves do not have a toxic effect, but under the influence of some intestinal bacteria they can turn into nitrites, which have significant toxicity. Nitrites, combining with blood hemoglobin, convert it to methemoglobin, which prevents the transfer of oxygen through the circulatory system; a disease develops - methemoglobinemia, especially dangerous for children. Symptoms of the disease: fainting, vomiting, diarrhea.
New ways to reduce nutrient losses and limit environmental pollution :
To reduce nitrogen losses from fertilizers, slow-acting nitrogen fertilizers and nitrification inhibitors, films, additives are recommended; encapsulation of fine-grained fertilizers with shells of sulfur and plastics is introduced. The uniform release of nitrogen from these fertilizers eliminates the accumulation of nitrates in the soil.
Of great importance for the environment is the use of new, highly concentrated, complex mineral fertilizers. They are characterized by the fact that they are devoid of ballast substances (chlorides, sulfates) or contain a small amount of them.
Separate facts of the negative impact of fertilizers on the environment are associated with errors in the practice of their application, with insufficiently substantiated methods, terms, rates of their application without taking into account soil properties.
The hidden negative effect of fertilizers can be manifested by its effect on the soil, plants, and the environment. When compiling the calculation algorithm, the following processes should be taken into account:
1. Impact on plants - a decrease in the mobility of other elements in the soil. As ways to eliminate negative consequences, the regulation of effective solubility and effective ion exchange constant is used, due to changes in pH, ionic strength, complexation; foliar top dressing and the introduction of nutrients into the root zone; regulation of plant selectivity.
2. Deterioration of the physical properties of soils. As ways to eliminate negative consequences, the forecast and balance of the fertilizer system are used; structure formers are used to improve soil structure.
3. Deterioration of water properties of soils. As ways to eliminate the negative consequences, the forecast and balance of the fertilizer system are used; components that improve the water regime are used.
4. Reducing the intake of substances into plants, competition for absorption by the root, toxicity, changes in the charge of the root and root zone. As ways to eliminate negative consequences, a balanced fertilizer system is used; foliar plant nutrition.
5. Manifestation of imbalance in root systems, violation of metabolic cycles.
6. The appearance of an imbalance in the leaves, a violation of metabolic cycles, a deterioration in technological and taste qualities.
7. Toxication of microbiological activity. As ways to eliminate negative consequences, a balanced fertilizer system is used; increase in soil buffering; introduction of food sources for microorganisms.
8. Toxication of enzymatic activity.
9. Toxication of the animal world of the soil. As ways to eliminate negative consequences, a balanced fertilizer system is used; increase in soil buffering.
10. Decreased adaptation to pests and diseases, extreme conditions, due to overfeeding. As measures to eliminate negative consequences, it is recommended to optimize the ratio of batteries; regulation of fertilizer doses; integrated plant protection system; application of foliar feeding.
11. Loss of humus, change in its fractional composition. To eliminate the negative consequences, organic fertilizers are applied, the creation of a structure, pH optimization, regulation of the water regime, and the balance of the fertilizer system.
12. Deterioration of physical and chemical properties of soils. Ways to eliminate - optimization of the fertilizer system, the introduction of ameliorants, organic fertilizers.
13. Deterioration of physical and mechanical properties of soils.
14. Deterioration of the air regime of the soil. To eliminate the negative effect, it is necessary to optimize the fertilizer system, introduce ameliorants, and create soil structure.
15. Soil fatigue. It is necessary to balance the fertilizer system, strictly follow the crop rotation plan.
16. The appearance of toxic concentrations of individual elements. To reduce the negative impact, it is necessary to balance the fertilizer system, increase soil buffering, sedimentation and removal of individual elements, and complex formation.
17. Increasing the concentration of individual elements in plants above the permissible level. It is necessary to reduce fertilizer rates, balance the fertilizer system, foliar top dressing in order to compete with the entry of toxicants into plants, and introduce antagonists of toxicants into the soil.
Main reasons for the appearance of a latent negative effect of fertilizers in soils are:
Unbalanced use of various fertilizers;
Exceeding the applied doses in comparison with the buffer capacity of individual components of the ecosystem;
Directed selection of fertilizer forms for certain types of soils, plants and environmental conditions;
Incorrect timing of fertilizer application for specific soils and environmental conditions;
The introduction of various toxicants together with fertilizers and ameliorants and their gradual accumulation in the soil above the permissible level.
Thus, the use of mineral fertilizers is a fundamental transformation in the sphere of production in general, and most importantly in agriculture, which makes it possible to fundamentally solve the problem of food and agricultural raw materials. Without the use of fertilizers, agriculture is now unthinkable.
With proper organization and control of application, mineral fertilizers are not dangerous for the environment, human and animal health. Optimal science-based doses increase plant yield and increase production.
Conclusion
Every year, the agro-industrial complex more and more resorts to the help of modern technologies in order to increase soil productivity and crop yields, without thinking about the impact they have on the quality of a particular product, human health and the environment as a whole. Unlike farmers, environmentalists and doctors around the world question the excessive enthusiasm for biochemical innovations that have literally occupied the market today. Fertilizer manufacturers talk side by side about the benefits of their invention, without mentioning a word about the fact that improper or excessive fertilization can have a detrimental effect on the soil.
Experts have long established that an excess of fertilizers leads to a violation of the ecological balance in soil biocenoses. Chemical and mineral fertilizers, especially nitrates and phosphates, worsen the quality of food products, and also significantly affect both human health and the stability of agrocenoses. Ecologists are especially concerned about the fact that biogeochemical cycles are violated in the process of soil pollution, which subsequently leads to an aggravation of the general environmental situation.
List of used literature
1. Akimova T. A., Khaskin V. V. Ecology. Man - Economy - Biota - Environment. - M., 2001
2. V. F. Val’kov, Yu. A. Shtompel, and V. I. Tyul’panov, Soil Science (Soils of the North Caucasus). – Krasnodar, 2002.
3. Golubev G. N. Geoecology. - M, 1999.
