RU2805255C1 - Method for reclamation of clay and loamy lands in the taiga zone, contaminated with highly mineralized waters - Google Patents

Abstract

FIELD: environmental protection.

SUBSTANCE: biological reclamation of soils and land contaminated with highly mineralized sulfate waters. The reclamation is carried out over a two-year period, for this, in the first year in spring, a plot of cultivated contaminated land is plowed up, sawdust of hardwoods is introduced into it. Next, carbamide is applied at the rate of 6-8 kg of urea per 1 m³ of sawdust applied, followed by cultivation of the topsoil. In the second year, in spring, sphagnum peat with a weak acid medium is introduced into the soil, at the rate of 25-30 m³ per 1 ha, and then a complex mineral nitrogen-phosphorus-potassium fertilizer is applied at the rate of 200 kg per 1 ha. The upper soil layer is cultivated to a depth of 10-15 cm, then after 2-3 weeks a vegetation cover is formed on the cultivated lands by sowing the soil with a grass mixture consisting of timothy grass, red clover, meadow fescue and red fescue, taken at a mass ratio of 1:1:2.8:1.2, respectively. Moreover, the ratio of the volume of sawdust with carbamide introduced into the soil in the first year to the volume of sphagnum peat introduced into the soil in the second year is 1:0.125÷0.150, respectively.

EFFECT: increase in the efficiency of reclamation of disturbed lands in the taiga zone by improving the water and physical properties of the soil, reducing the content of sulfate salts in it, reducing the alkalinity of the soil, reducing the content of gypsum, while increasing the content of organic matter and mineral elements in the soil.

5 cl, 2 dwg

Description

The invention relates to environmental protection, in particular to the biological remediation of soils (soils) contaminated

highly mineralized sulfate waters, for example, as a result of accidents and operational losses during production, and can be used in the potash and oil industries.

Land reclamation is a set of works aimed at restoring the productivity and national economic value of disturbed lands, as well as improving environmental conditions in accordance with the interests of society.

The main objects of reclamation at mining fields are most often saline soil areas that have lost their economic value due to their pollution. As a result of economic activity, the condition of the soil is disturbed and an excess of salts, in particular sulfates, is formed, which has a detrimental effect on the biocenosis. It should be noted that pollution in potash mining and oil production is usually sodium chloride. However, when the flow of mineralized water stops, chlorides are quickly washed out under leaching conditions, and sulfates remain in the soil, which subsequently ensure sulfate salinization of the land and gypsum formation. Sulfates can act as poisons on plants, causing salt poisoning, and the roots lose their ability to absorb water from the soil. There can be no talk of soil fertility and high yields on saline soils - the basis of fertility - humus is lost, mineralized, soil moisture is bound, the physical properties of the soil become unfavorable for plants, and the activity of soil organisms is inhibited. That is why the problem of reclamation of such contaminated soils, especially in the taiga zone, is urgent.

And given that a large number of industrial potash and oil production facilities, which are the main sources of soil pollution with sulfate formation waters, are located in the taiga zone, the search for new methods of reclamation of taiga lands is of paramount importance.

Usually, for the purpose of reclamation in conditions of salt pollution, a biological method of reclamation is used, which involves sowing perennial grasses with the application of fertilizers that promote the rapid overgrowth of disturbed and saline soils and the activation of self-purification processes.

The traditional method of reclamation is to backfill the mined-out quarry with a layer of peat, followed by disking it and mixing it with the top layer of sand, and then planting forest crops or sowing perennial grasses (GOST 17.5.3.05-84 “Nature conservation. Land reclamation. General requirements for land development”).

There is a known method for recultivating disturbed soils by covering the reclaimed surface with an organic substrate. In this case, a layer of sawdust is first laid, and then a layer of sludge from treatment facilities. An additional disinfectant, such as bleach, is added to the organic substrate, and after laying the sludge, it is treated with ammonia. (Auth. St. USSR N 1360615). The disadvantage of this method is its low efficiency due to the labor intensity of the formation of the fertile layer, the low survival rate of plants on the substrate and, as a result, the duration of the process of reclamation of disturbed soils.

There is a known method for the biological reclamation of fertile lands contaminated with mineralized formation waters ("Temporary recommendations for the reclamation of lands contaminated with oilfield formation waters. Agro-Industrial Committee of the Tatar Autonomous Soviet Socialist Republic. Kazan Order of Lenin "Badge of Honor" Agricultural Institute named after M. Gorky, Kazan, 1987) , including such technological operations as desalinization, namely the implementation of moisture-accumulating agricultural practices in the form of deep plowing, retention of melt water, washing with water, desalinization by adding a chemical ameliorant to the soil, sowing salt-tolerant crops. However, the method carried out according to this technique does not have a clear, consistent technologies for performing work, the degree of pollution and the time of technological operations are not taken into account depending on the start of work by season, there is no dependence between the stages of work and the types and sequence of agricultural practices and phytomeliorative measures, there are no necessary technological operations such as the application of mineral and organic fertilizers.

There are known methods for removing inorganic and organic water-soluble compounds from soil and grounds, based on the use of sorbents containing sphagnum (RF Patent No. 2019943) or hydrolytic lignin (RF Patent No. 2147165). The disadvantage of this method is the difficulty of mechanical removal from the surface of soils and ground, and limited application.

It is also known that the removal of inorganic and organic compounds from soils can be enhanced by using a solution of humic substances as a chelating agent (RF Patents No. 2109425 and No. 2108016).

From the RF patent No. 2113094 there is known a method for the biological reclamation of sandy lands contaminated with drilling wastewater in desert and semi-desert zones. According to the known method, the land is cultivated, reclamation is carried out in stages over three years, and in the first year the land is cultivated by loosening to a depth of 22-25 cm, then chiseling is carried out to the same depth and chemical ameliorants are applied, after which plowing is carried out to a depth of 25-25 cm. 27 cm, in the second year phytomeliorative measures are carried out in the form of planting shrubs and subshrubs, in the third year shrubs, subshrubs and grasses are also planted, and in the first year, before loosening, sorbents are applied to the surface of the earth, after applying sorbents, loosening is carried out to a depth of 25- 27 cm with subsequent rinsing by sprinkling. However, this method is applicable only in desert conditions on sandy soils.

From the prior art (RF patent No. 2459398) a method is known for recultivating soils contaminated with mineralized waters. This method includes intensive loosening, application of sorbent, chemical ameliorant, intensive sprinkling and planting of crops. In this case, dry pressed briquettes of excess sludge are used as a sorbent. Spent briquettes are removed from the soil by sifting the latter on vibrating screens. Crumbly wet excess sludge is used as a chemical ameliorant. When the salt content in the soil is more than 10 wt. %, carry out preliminary removal and washing of saline soil with fresh water. Water consumption for irrigation by sprinkling is 450-500 m ³ /ha. Halophytic plants, for example, amaranth and wormwood, are used as plant crops. The method is not suitable for reclamation of lands with sulfate salinization and may cause a rise in groundwater levels.

There is a method for the reclamation of saline soils (RF patent application No. 97109011), which consists in sowing halophytes on saline soil: European saltwort and/or knobby sarsazan, and sowing is carried out together with xeroform plants - kokpek and/or biyurgun with their subsequent harvesting. Known method Suitable for clay soils confined to arid conditions and with chloride type of salinity. Sulfate salinity is not taken into account.

At the same time, the prior art has not identified known methods for the reclamation of clayey and loamy lands in the taiga zone contaminated with highly mineralized sulfate waters, so it is not possible to select the closest analogue to the claimed object.

The technical objective of the invention is to develop a method for reclamation and restoration of stable grass cover on clay and loamy soils of the taiga zone, after soil contamination with highly mineralized sulfate waters.

The technical result is to increase the efficiency of reclamation of disturbed lands in the taiga zone by improving the water-physical properties of the soil, reducing the content of sulfate salts in it, reducing soil alkalinity, reducing the gypsum content, while simultaneously increasing the content of organic matter and mineral elements in the soil.

The stated technical result is achieved by the proposed method of reclamation of clay and loamy lands in the taiga zone, contaminated with highly mineralized waters, according to which reclamation is carried out over a two-year period, for this purpose, in the first year in the spring, a plot of cultivated contaminated land is plowed up, sawdust of deciduous trees is added to it, then urea is added at the rate of 6-8 kg of urea per 1 m ³ of applied sawdust, followed by cultivation of the top layer of soil; in the second year in the spring, high-moor peat, which has a slightly acidic environment, is added to the soil at the rate of 25-30 m ³ per 1 ha, and then a complex mineral nitrogen-phosphorus-potassium fertilizer is applied at the rate of 200 kg of this fertilizer per 1 ha, the top layer of soil is cultivated to a depth of 10-15 cm, then after 2-3 weeks a vegetation cover is formed on the cultivated lands by sowing the soil with a grass mixture consisting of meadow timothy, red clover, meadow fescue and red fescue, taken in a mass ratio of 1:1:2.8:1.2, respectively, and the ratio of the volume of sawdust with urea added to the soil in the first year to the volume of topsoil applied to the soil in the second year peat is 1 to 0.125-0.150, respectively.

Hardwood sawdust is added to the cultivated soil at the rate of 200 m ³ per 1 ha at 15-20% humidity.

Cultivation of the top layer of soil after adding sawdust and urea is carried out to a depth of 10-15 cm.

Complex mineral nitrogen-phosphorus-potassium fertilizer includes nitrogen: phosphorus: potassium in the ratio of 16%: 16%: 16%.

Sowing of the soil with a grass mixture is carried out at the rate of meadow timothy 15 kg/ha, red clover 15 kg/ha, meadow fescue 42 kg/ha and red fescue 18 kg/ha. The specified technical result is achieved due to the following.

It should be noted that land reclamation always involves restoration work, which, as a result of its implementation, should increase the fertility of the soil and return it to its former natural qualities. There are two stages of reclamation: technical and biological. Typically, to restore saline soils, biological reclamation is used, which includes a range of agrotechnical work carried out to restore fertility and other soil indicators.

At the same time, methods of biological reclamation for different types of land, as a rule, differ from each other. This is due to the fact that different soils differ in composition, physical parameters, and structure. For example, the reclamation of saline sandy lands is aimed not only at restoring their fertility by removing toxicants, but also provides technological methods to prevent wind erosion of sandy soil; land reclamation in the Far North involves techniques aimed at preserving heat in the soil so that the planted plants do not freeze, for example, seed granulation, etc.

The main feature of the taiga zone, the soil of which is to be reclaimed by the proposed method, is the presence of wetlands due to low evaporation. The main feature characteristic of taiga soils is the presence of silica. Because of this, a washout horizon is formed. As a result, the soil from above is washed away and settles below, forming a dense horizon of stormy color. All taiga soils are united by the absence of a deep fertile layer. The top layer is thin and infertile. There is especially a lack of calcium and nitrogen. Low temperatures slow down the process of decomposition of organic substances (https://karatu.ru/pochva-tajgi/#i-30). Based on this, the set of features of the proposed method has its own peculiarity, in contrast to known methods of reclamation on other soils, and is aimed at the reclamation of taiga lands contaminated with sulfate compounds.

A feature of soil salinization by highly mineralized waters in taiga landscapes and leaching water regime is the formation of gypsum-containing soils (soils), which are characterized by unfavorable mechanical properties and an alkaline reaction.

Due to the fact that reclamation using the proposed method is carried out over a two-year period and during each period the soil is treated with a certain reclamation material, a guaranteed reduction in sulfate salts is ensured. It is important that the reclamation materials in the first and second years of treatment differ in composition and are simultaneously used in a strictly stated ratio, namely: the volume of sawdust with urea added to the soil in the first year to the volume of high-moor peat introduced into the soil in the second year is 1 to 0.125-0.150, respectively. It was experimentally established that with a different ratio of these mixtures, the reduction in the content of sulfate salts in the soil of the taiga zone occurs less effectively, which does not allow the fertility of the land to be fully restored in two years.

In addition, it was also established experimentally that during the reclamation of soils in the taiga zone contaminated with sulfate salts, an important point was the selection of grasses when sowing the soil with a grass mixture. Taking into account the peculiarities of the structure of taiga lands, the proposed grass mixture should consist of meadow timothy, red clover, meadow fescue and red fescue, taken in a mass ratio of 1: 1: 2.8: 1.2, respectively. Timothy grass, meadow fescue and red fescue are cereal plants. And red clover goes with legumes. All of these perennial plants are winter-hardy. Leguminous plants with a tap root are able to extract nutrients and water from the deep layers of the soil, cereals - from the upper layers. Nutrients and moisture are used evenly throughout the root layer, which makes it possible to obtain a significantly larger yield than when cultivating these crops separately. That is, in the presence of legumes, cereal plants grow better. Moreover, as it turned out, when using exactly the declared qualitative and quantitative composition of the grass mixture, a simultaneous reduction in the content of sulfate salts in the soil and a decrease in soil alkalinity are ensured.

The introduction of sawdust with urea (urea) into the soil and the subsequent application in the second year of high-moor peat with complex nitrogen-phosphorus-potassium fertilizer in the stated ratios of sawdust and peat ensures an increase in the content of organic matter and mineral elements in the soil, while simultaneously reducing the content of sulfates.

Thanks to the set of agro-reclamation techniques of the proposed method, high efficiency of reclamation of lands in the taiga zone contaminated with mineralized sulfate waters is ensured, and fertility restoration is ensured.

As a result of the implementation of the proposed method, a new mini-ecosystem is formed that has the ability to self-heal, bind, neutralize and decompose toxic sulfate compounds.

Additional studies were carried out on an experimental plot, the soil of which was also characterized by the presence of large amounts of sulfates.

Reclamation was carried out with the difference that the amount of sawdust with urea (urea) at the first stage and the subsequent introduction of high-moor peat at the second stage was in a different volumetric ratio, namely 1 to 0.09, respectively. The remaining operations were performed in accordance with the claimed method. The following results were obtained: reduction of sulfates by 10% compared to the original; The pH remained virtually the same; the seeds of the grass mixture sprouted in patches, unevenly, i.e. there was no uniform vegetation cover. This proves the significance of the claimed feature in terms of the ratio of reclamation materials used in the first and second years of reclamation. The connection of this characteristic with the proposed composition of the grass mixture is also significant.

Thus, the proposed invention is characterized by a set of interdependent features, which all participate in ensuring the achievement of a technical result, because this result only appears when using this technical solution as a whole.

In addition, any definitions used in this application should be considered as illustrative and not as limiting of the present invention.

The proposed method is illustrated by the following figures:

- in Fig. 1. shows the dynamics of the content of sulfate ions and calcium ions in the water extract of the studied soil in the taiga zone (0-10 cm layer);

- in Fig. 2. The acidity of the soil during different periods of reclamation is given. An example of the implementation of the proposed method.

The proposed method was used for the reclamation of an area in the taiga zone that was saline as a result of an emergency brine spill.

Before reclamation, the soil was characterized by an alkaline reaction (pHwater = 8.2), the content of sulfate ions and calcium ions in the water extract of the root layer of the contaminated soil was 17.6 mmol/100 g and 9.5 mmol/100 g, respectively. There is no chloride salinity at the site.

Soil reclamation was carried out in two stages in the following sequence.

In the first year, in the spring (late April - early May), the top layer of soil was plowed, after which sawdust was added, which was evenly placed over the site, then urea (urea) was added. Sawdust and urea were mixed with the top layer of soil by cultivating to a shallow depth (about 10-15 cm). In this case, hardwood sawdust was used at the rate of 40 tons (200 m ³ ) per 1 ha at 15-20% humidity. The calculation of the required amount of carbamide (urea) to acidify sawdust and eliminate nitrogen deficiency in the root layer of soil was calculated by volumetric mass, and this amount in a specific example was 6 kg of urea per 1 m ³ of the specified sawdust (the proposed method in optimal cases involves the use of urea in an amount 6-8 kg per 1 m ³ of sawdust).

In the second year, in the spring, high-moor peat, which has a slightly acidic environment, was added to the site at the rate of 25 m ³ per 1 ha (the proposed method in optimal cases involves the use of high-moor peat in an amount of 25-30 m ³ kg per 1 ha), then nitrogen was added - phosphorus-potassium mineral fertilizers in the form of NPK, nitroammophosphates, which include nitrogen: phosphorus: potassium, for example, (but not limited to this), in the ratio of 16%: 16%: 16%, at the rate of 200 kg per 1 ha. At the same time, it was taken into account that the ratio of the volume of sawdust with urea added to the soil in the first year to the volume of high-moor peat introduced into the soil in the second year was 1 to 0.125, respectively (the proposed method in optimal cases provides for the ratio of the volume of sawdust added to the soil in the first year with urea to the volume of high-moor peat introduced into the soil in the second year 1 to 0.125÷0.150, respectively).

Next, the top 10-15 cm layer of soil was cultivated.

After 2-3 weeks, a grass mixture was sown, consisting of meadow timothy, red clover, meadow fescue and red fescue, taken in a mass ratio of 1:1:2.8:1.2, respectively. Sowing of grasses was carried out by uniformly distributing seeds over the surface of the soil using the scattering method. After scattering the seeds, the surface layer of soil was cultivated. The specific composition of the grass mixture was as follows: meadow fescue 42 kg/ha, red fescue 18 kg/ha, timothy 15 kg/ha and red clover 15 kg/ha (but not limited to this optimal option). To calculate the seeding rate, a coefficient of 1.5 was used, since it meant the restoration of soil and vegetation cover specifically in the taiga zone and under the negative influence of climate in this zone.

After reclamation, the following effect was observed:

- reduction in the amount of sulfate ions by 60% (was 17.6 mmol/100 g of soil; now 10.5 mmol/100 g of soil) (see Fig. 1);

- decrease in pH value from 8.2 to 7.7 (i.e., the soil has practically become neutral) (see Fig. 2).

Also noteworthy is the improvement in the water-physical properties of the soil and an increase in the content of organic matter.

Before reclamation, the soil contaminated with sulfates in the taiga zone was characterized by a very dense composition, clay composition, and the content of organic matter was less than 1%. Mechanical treatment of the surface layer, the introduction of sawdust and urea at the first stage, and complex fertilizer at the second stage - high-moor peat, contributed to the appearance of a lumpy structure to a depth of 10-12 cm and an increase in the content of organic matter to 6.3%.

The content of gypsum in the surface layer of the cultivated soil increased slightly, however, the combination of reclamation measures of the proposed method reduced the negative water-retaining effect of gypsum on vegetation, which was confirmed by the presence of a continuous surface cover of sown grasses.

Based on the results of the second year of reclamation work for reclamation crops, good germination and plant growth are observed until the seeds ripen.

Thus, the proposed technology is effective for the reclamation of mineralized soils of the taiga zone contaminated with sulfates, and allows for the complete restoration of the fertility of disturbed lands in two years.

The need for watering is noted if summer weather conditions are characterized by high temperatures and low precipitation.

The inventive method can significantly reduce soil phytotoxicity, increase soil fertility, optimize mechanical properties and ensure stable plant cover.

Claims (5)

1. A method for the reclamation of clayey and loamy lands in the taiga zone, contaminated with highly mineralized waters, characterized by the fact that reclamation is carried out over a two-year period; for this, in the first year in the spring, a plot of cultivated contaminated land is plowed up, sawdust of deciduous trees is added to it, then urea is added from calculating 6-8 kg of urea per 1 m ³ of sawdust applied, followed by cultivation of the top layer of soil; in the second year in the spring, high-moor peat, which has a slightly acidic environment, is added to the soil at the rate of 25-30 m ³ per 1 ha, and then a complex mineral nitrogen-phosphorus-potassium fertilizer is applied at the rate of 200 kg of this fertilizer per 1 ha, cultivation is carried out top layer of soil to a depth of 10-15 cm, then after 2-3 weeks a vegetation cover is formed on the cultivated lands by sowing the soil with a grass mixture consisting of meadow timothy, red clover, meadow fescue and red fescue, taken in a mass ratio of 1:1:2 .8:1.2, respectively, and the ratio of the volume of sawdust with urea added to the soil in the first year to the volume of high-moor peat introduced into the soil in the second year is 1:0.125÷0.150, respectively. 2. The method according to claim 1, characterized in that hardwood sawdust is added to the cultivated soil at the rate of 200 m ³ per 1 hectare at 15-20% humidity. 3. The method according to claim 1, characterized in that the cultivation of the top layer of soil after adding sawdust and urea is carried out to a depth of 10–15 cm. 4. The method according to claim 1, characterized in that the complex mineral nitrogen-phosphorus-potassium fertilizer includes nitrogen:phosphorus:potassium in the ratio 16%:16%:16%. 5. The method according to claim 1, characterized in that the soil is sowed with a grass mixture at the rate of meadow timothy 15 kg/ha, red clover 15 kg/ha, meadow fescue 42 kg/ha and red fescue 18 kg/ha.