How to do a soil analysis on a site. Can I do a soil test myself? What is chemical analysis of soil, what types are there?
For a good and healthy harvest, many factors must be taken into account. One of these is the quality of the soil that is used to grow plants. Also, such indicators as the health of humans and domestic animals depend on its quality. Even compliance with various instructions sometimes cannot give good results when growing various plants. In this case, the issue may lie precisely in the quality and composition of the land. It is often the culprit of soil damage.
Several main purposes of such analyzes can be identified. The most the main objective is to find out how suitable such soil is for Agriculture and human life. Finding out its composition can answer this question, as well as understand the type of soil. In case of violation of norms, such research acts as a way to find out the cause of pollution and eliminate it.
There are many reasons why soil becomes of poor quality and most often they are related to human activities. When conducting research in our laboratory, you will receive not only accurate results, but also subsequent consultation with a specialist. This way you will know about the condition of the soil and what actions need to be taken to improve it.
Causes of soil pollution
So what are the causes of soil pollution? There may be several of them, but human activity is the main factor. Often spending Natural resources, no one thinks that this is not an inexhaustible source and that they need to be restored. It is also common for people to turn a blind eye to environmental damage for their own benefit. After all, sometimes it is much cheaper to dump production waste without recycling it. Therefore, it is important not only to inspect the land for compliance with standards, but also to take measures to improve the condition of the soil.
Among the main reasons are:
- Industrial emissions of harmful substances. They can be discharged directly into the soil or into the air and water, where they ultimately harmful substances they still end up in the ground. They do not decompose naturally and such contaminated soil is not suitable for use. As a result of their activities, metallurgical enterprises emit various heavy metals. Machine-building plants can pollute the soil with such hazardous substances like arsenic and potassium cyanide. Pulp and paper mills and plastics manufacturing plants are emerging as sources of phenol emissions.
- Pollution from cars. As a result of the increase in the number of cars, a huge amount of harmful substances are released into the air. This is especially noticeable where there are large highways and polluted air accumulates. The heavy metals contained therein and chemical substances settle on the ground or cause destructive acid rain. As a result of this impact, severe damage is caused to the soil, which changes its properties and structure. Not only is it incapable of providing plants with the necessary nutrients, but it can also be downright dangerous. That is why it is not recommended to eat food that has grown close to highways and major roads.
- By monitoring the quality of grown plants and taking care of them, a person can also negatively affect the condition of the soil. Various chemicals and pesticides used on crops end up in the ground and accumulate there. Since they are not recycled, without human intervention these chemicals will remain in the soil and end up in The groundwater and poison both plants and humans.
- Household waste, which ends up in a landfill, pollutes not only environment. As a result of the large accumulation of various wastes under open air Harmful substances begin to be released, which eventually enter the soil and infect it.
But not only such basic causes of soil pollution pose a threat to humans. The soil is also an excellent breeding ground for various harmful microorganisms, which if entering the human body can cause serious consequences. Therefore, the method of soil analysis depends mainly on what kind of result is needed and what parameters will be studied.
Methods for analyzing soil for contamination
Depending on the final goal of the study, methods for analyzing soil samples are also selected. But despite the fact that the goals and objectives of the study may differ, in the end the results will still show how given soil complies with standards and is safe.
Therefore, each study of soil samples has its own specifics and allows the most complete and accurate assessment of soil quality. The following types are distinguished:
- Granulometric or mechanical soil analysis. It consists of sifting granules and microelements of the soil. Then they are weighed and counted. This method gives an idea of the content in the ground various metals, trace elements or minerals. As a result, based on the identified composition, conclusions can be drawn about the type of soil in question.
- Next comes a chemical analysis of the soil. It analyzes the composition of the soil more deeply. Thanks to this, not only the composition and appearance is established, but also various features. TO chemical features can be attributed: chemical composition, acidity, presence of chemical active substances and various poisons. Such analysis can be photometric, gravimetric and chromatographic. The photometric method is used to determine phenol and for this purpose the samples are treated with special reagents. Gravimetric or otherwise weight analysis is based on measuring the mass of a substance. The chromatographic method involves analyzing mixtures of a substance. This type of analysis is most often used when transferring soil from one category to another.
- In order to find out how suitable the land is for agriculture, agrochemical soil analysis is used. It is similar to chemical method, but aims specifically to identify the components necessary for plants in the soil, as well as the presence of harmful substances.
- The mineral composition of the soil is determined by mineralogical analysis. Thanks to it, you can find out what components are included in the soil. They affect its structure, moisture absorption and much more. Such research is carried out not only to find out whether the soil is suitable for agricultural needs, but also during construction.
- And the last of the main types of analyzes is radiological soil analysis. The purpose of the study is to detect radioactive substances in the soil. Such substances are very dangerous for humans and provoke various serious diseases. Therefore, it is important to control the soil nearby various industries and nuclear power plants. In this case, enterprises constantly undergo this test in order to detect the entry of hazardous particles into the soil. This type of pollution takes a very long time to remove from the soil and can have a detrimental effect on all living organisms.
Selection of soil samples in natural conditions and their preparation for laboratory research are the main issue of the methodology, on which the result of all subsequent determinations depends. It is necessary to correctly designate places for soil sampling, which would allow identifying areas that are subject to the greatest contamination and, conversely, those that are good in their sanitary condition. To do this, one or more sites are selected near existing sources of pollution, and the other - in a place remote from them. The depth of soil sampling is determined depending on the nature of the soil, the task and type of laboratory research.
To determine the mechanical and chemical composition of the soil, sampling is carried out at 3-5 points diagonally from an area of 25 sq.m. from a depth of 0.25 m, and if necessary - from a depth of 0.75 - 1 m and ],75 - 2 m. Samples are taken with a drill or shovel, mixed thoroughly and from the samples taken from each horizon, a single average sample is made for it weighing about 1 kg, which is placed in a jar with a stopper, a number is put on the label and sent to the laboratory with an accompanying document indicating the place and time of sampling, depth, meteorological features at the time of sampling and what should be determined in the soil.
In the laboratory, soils are weighed, mixed, sifted and, depending on the purpose of the study, analyzed in their natural form or in an air-dry state, for which the soil is dried in air at room temperature followed by additional sifting through a sieve with holes 1 mm in diameter. The analysis of natural freshly taken soil begins as soon as possible, since due to ongoing biochemical processes Significant changes may occur in the soil. If it is not possible to test the soil on the same day, you can store it in the refrigerator for several days or add preservatives.
For bacteriological analysis, soil samples in the amount of 200-300 g are taken with sterile instruments also at 3-5 points of an area of 25 sq.m., placed in sterile jars and an average sample is made from them. Samples are taken from the depth at which bacterial contamination is suspected. In populated areas, it is recommended to examine first of all the surface layers of soil to a depth of 20 cm. From areas of irrigation fields, samples are taken at a depth of 20 cm. When studying the effects of soil pollution on groundwater and open reservoirs, samples should be taken at a depth of 0.75 - 2 m. In the latter case, a Nekrasov drill is used for this, and if it is not available, a hole is dug and samples are taken from each side with a sterile spatula or knife. When monitoring the disinfection of household waste using the soil method, soil samples are taken from a depth of 25, 100 and 150 cm, depending on physical properties soil. Sterilization of instruments for taking soil samples is carried out at each new site by washing with water, wiping with alcohol and finally burning.
Jars with soil samples are closed with cotton plugs, wrapped in paper and bandaged. The jar is numbered, the necessary data is recorded (air and soil temperature, etc.) and immediately sent to the laboratory. If jars are not available, soil samples can be transferred in sterile plastic bags or sterile parchment paper. In the laboratory, the soil is poured onto sterilized drying cabinet paper, freed from roots, crushed stone, glass, etc., large lumps of soil are kneaded, mixed thoroughly and from here a sample of soil is taken for research. If, upon delivery of the samples to the laboratory, it is not possible to begin bacteriological research, they can be stored in the refrigerator at 1-5 degrees C for no more than 18 hours, since changes in the composition of the microflora occur over time.
For sanitary-virological analysis, samples of the arable layer are first taken, since under natural conditions enteroviruses are adsorbed mainly by the upper layers of soil. According to G.A. Bagdasaryan, samples are taken separately from ridges and furrows from a depth of 0-20 cm, to determine the penetration of enteroviruses deep into the soil - at a depth of 50 and 100 cm. The sampling technique is similar to that used when taking samples for bacteriological research; therefore, the same soil samples can be used for both analyses.
Primary processing of samples should be carried out on the day of sample collection immediately upon delivery to the laboratory. It is allowed to carry out the analysis on another day, no later than 24 hours later, provided that the samples are stored in the refrigerator at A gr.C. Longer storage entails a drop in the titer of enteroviruses and the possibility of their isolation decreases.
For helminthological analysis, soil samples are taken separately from the surface and from a depth of 2-10 cm, since, depending on the depth, helminth eggs survive for various terms. From each plot of 50 sq.m. take at least 10 samples weighing approximately 100 grams in different places along the diagonal and from them average samples weighing about 1 kg are made separately for each horizon.
Soil samples from surface layers they are taken with a metal spatula, a tablespoon or a scoop, and from the depths with a drill or a shovel. Samples are collected and transported in glass jars with a stopper or in plastic bags, providing the container with a label and noting, as usual, the time and place of sampling, external conditions and so on. Upon delivery to the laboratory, soil samples, if they were not in glass jars, are poured into glass jars, mixed thoroughly and large particles removed. The analysis is carried out within the next few days; if this is not possible, then the samples taken are filled with a 3% solution of formalin in saline solution or a 3% solution of hydrochloric acid and stored in open jars at a temperature of 18-24 degrees C, stirring frequently to improve aeration. When the soil dries out, add clean water.
For radiometric analysis, soil sampling is carried out in accordance with the task. To determine radioactive contamination of the soil in a given area, several areas with an area of approximately 50 sq.m. are selected. and in the middle of each of them on an area of about 1 sq.m. remove the grass cover and cut out the soil for testing in the form of a piece measuring 10x10 cm, 5 cm thick. The sample is packed in an oilcloth or plastic material and sent to the laboratory indicating the place where the sample was taken, date, etc. Vegetation is taken in quantities of about 75 g and packaged separately.
For chemical analysis of soil, the “Methodology for measuring the mass concentration of mercury in soil samples by the method of flameless atomic absorption with thermal decomposition of samples” PND F 16.1.1-96 is used. At the same time, a methodology is established for measuring the mass concentration of mercury in soil samples by atomic absorption analysis (flameless atomic absorption method.)
To assess the mechanical composition of the soil, a Knopp sieve is used, consisting of a set of individual sieves with holes. various sizes– from 0.25mm to 10mm. Each hole size corresponds to a specific sieve size. A sample of selected soil (200-300g) is passed through Knopp sieves, resulting in particles remaining on individual sieves different sizes. By weighing the contents of each sieve and determining their percentage composition in relation to the weighed portion of the entire sample, its mechanical composition is approximately estimated.
According to N. Kachinsky’s classification, particles retained on a particular sieve are classified as a specific type of soil:
On sieves with 3-10mm holes - stones and gravel;
On sieves with 1-3mm holes - coarse sand;
On sieves with holes 1-0.25 mm - medium sand;
At the bottom of the sieve - fine sand and dust.
You can do a soil analysis at home without special knowledge or equipment. So, to determine the composition of the soil, five tablespoons of a prototype are enough. You need to carefully select organic residues and stones from it, then fill it with water.
After this, you need to close the jar and shake the contents thoroughly for several minutes. Let the container sit still for up to a week, while noticing the levels of sediment that appear.
First, sand will fall, later - dust, after 5-7 days - clay. Humus does not settle, but remains floating in the liquid, turning it brown. Now, using a ruler, you can find out the relative amounts of the main components of the soil.
You can also try making a ring 2 mm in diameter from wet soil from a “sausage” 2 mm thick. If:
- the result is a strong and smooth ring - this is clay;
- It was not possible to roll a “sausage” - the soil is sandy;
- the ring is strong and the ends are stuck together, only the “sausage” is a little cracked - heavy loam;
- the ring is strong, but falls apart in some places - medium loamy soil;
- The “sausage” is rolled, but falls apart when you try to roll it into a ring - sandy loam soil.
How acidic is the soil?
In gardening stores you can purchase special kits for determining soil acidity at home and in the field, so doing an independent analysis is not difficult.
Soil acidity is an important indicator when choosing vegetable and garden crops, fertilizing for beds and flower beds. Paper indicator strips will help you easily determine the pH value according to the color of the scale.
For the experiment, you will need to lower a linen bag with a soil sample into water (water and soil at a ratio of 5:1). After 5 minutes, lower the indicator into the liquid. At pH 7 the soil is neutral, above seven it is alkaline, below it it is acidic.
Does the soil breathe well?
It is very important to find out soil aeration, since good gas exchange is necessary for normal plant development. The soil “breathes” due to the pores, but if they are filled with water, the penetration of oxygen stops. Usually problem areas on personal plot– heavy clay islands, layers, inclusions.
The amount of air is indicated by the color of the clay soil:
- blue – oxygen deficiency;
- reddish – oxygen is present.
Is the soil wet?
If you dig a hole in your garden plot and it fills with moisture, it means that they are located close groundwater. When growing plants, it is very important to know how moisture-loving they are and what the hydrological characteristics of the land in the country are.
The plants themselves, which feel great in a particular area of soil, help to guess the degree of soil moisture. So, wild rosemary, cinquefoil, snake knotweed, blueberry, and meadow geranium love very moist soil. Moderately wet - stone fruit, lingonberry, cornflower and meadow clover, and dry - bearberry, sedum, feather grass.
How fertile is the soil?
Careful observations of different plots of land at the dacha will help determine the degree of their fertility. Certain conclusions can be drawn based on the following characteristics.
- The more earthworms there are in the soil, the more fertile it is.
- Weeds such as white clover, chamomile, and daisy often grow on depleted soils.
- Yellow gorse bushes, sundews and cat's paws thrive on infertile soil.
- Horsetails and creeping buttercups stubbornly growing on the ground are a sign of heavy, loose, waterlogged soil.
- Fireweed, raspberry, celandine, woodlice and nettle are very fond of fertile soil saturated with nitrogen.
Depleted soil and excess fertilizer are equally harmful to garden crops, so an annual soil analysis will help give it exactly what it needs and get a good harvest.
The most accurate results can be obtained with a comprehensive analysis, which is offered by specialized laboratories. For this you only need to prepare the material, that is, the soil from your plot of land, for analysis, but this must be done correctly, since the degree of accuracy of the results largely depends on this.
A soil sample from the site should be taken before applying fertilizers and liming. In different places of the land you need to make holes to the depth of a spade bayonet or a little deeper. It is this depth that most plants need to freely accommodate and nourish the root system, therefore, the soil must be comprehensively examined in this area. In total, at least 15-20 holes should be dug, which will allow for greater objectivity of the analysis, and thus, at least 15-20 samples should be taken from 100 m2 of site area. Then, sequentially, from the wall of each of the holes you need to scrape off a thin layer of earth with a scoop in the direction from bottom to top and put it in a bucket, after which all the samples are thoroughly mixed in the bucket. At least 1 kg received soil mixture put in plastic bag and close it tightly.
When submitting soil for analysis to the laboratory, indicate the characteristics of your site, location and the main purpose for which you intend to use it. land plot(growing vegetables, fruit crops or anything else). Based on the analysis obtained, you will be able to accurately determine in which nutrients and microelements the soil especially needs, what fertilizers need to be applied and what measures should be taken to improve the composition of the soil.
An important role in assessing soil quality is played by its appearance, by which you can quite accurately determine the structure, some internal properties and quality of the soil. One of the most important external signs of soil is its color. If you dig a hole at least 1 m deep, you will get a soil profile, that is, the structure of the soil in cross-section. On the side wall of the pit, one can successively trace the alternation of soil layers and the change in their color towards the bottom of the pit. The color of the soil is directly related to such characteristics as the level of fertility.
This is a completely logical conclusion, since the appearance of the soil and its fertility are determined by numerous factors that influenced its formation. Dark soils, as a rule, are characterized by more high level fertility, as they represent Better conditions for the growth of plants and the activity of soil microorganisms than light soils. The color of dark soils is due to increased content they contain soil organic matter humus. It is humus good quality, contained in the soil in sufficient quantities, determines the rich dark color of the soil. However, not only humus provides one or another color of the soil, but also numerous chemical compounds, for example, iron oxides, which give the soil brown, reddish, reddish-rusty and yellowish shades. Plates of a bluish-gray or gray color may appear on the soil profile at different depths, which is a bad characteristic of the soil of the site, as it indicates the presence of constant waterlogging of the soil, which results in the formation of ferrous compounds. Such soil will require great efforts to improve, but a lot also depends on
depths of blue clay strata.
In addition to special analysis, there are a number of methods independent conduct soil analysis.
Of course, such methods will not produce a chemically accurate assessment of all the characteristics of the soil in a particular area, but they will give you an idea of its main parameters and allow you to make correct solution on further processing and fertilization of the soil. A home mini-laboratory will help with this, which is a set of reagents and indicators, equipped with a color scale for comparative analysis acid-base reaction of the soil using indicator paper and detailed description all possible soil tests. In addition, the soil can be examined visually. This will give you at least a fairly good idea of the structure and composition of the soil.
If you make a hole one or two shovels deep and examine the profile of the cut, then by the color of successive layers you can approximately determine what kind of soil you are dealing with. More often upper layer darker than subsequent ones, which indicates a higher content of organic matter or humus in it. Its thickness may vary, but it is advisable that it should not be less than 1015 cm, that is, the depth where plant rooting occurs. Peat soils They are almost black in color due to the high content of organic matter in them. The sandy layer of the earth has a yellowish
gray color, loamy layer - light brown with various shades, clay layer can be different colors- from brown and reddish to whitish.
Manual soil testing
If you are not entirely sure what the composition of the soil in your area is, you can check it in the following way: take a handful of damp, but not wet, soil and rub it between your fingers. If the soil texture is granular, if it does not stick together or roll into balls, you have sandy loam or sandy soil.
If the soil is grainy but rolls into a ball or clump, it is sandy loam.
If the soil has a grainy or sticky texture and you can roll it into a sausage between your palms, then you are dealing with oily sandy loam.
If the resulting sausage is flexible, it can be bent into a ring and it will not break, it is clay.
Knowing the structural properties of your soil can help you determine what steps you need to take to improve it.
When examining the soil manually, it is not difficult to see that individual soil particles are completely different from each other. In sandy soils or soils with a high sand content, solid particles are large and coarse and can be clearly felt by touch. The more the soil sticks together, the smaller and thinner its particles are, which indicates a high clay content in the soil. Good soil has a mixed composition of coarse and fine particles, which form into small loose lumps. Soil with a high humus content has a pleasant, healthy smell of forest soil, rotten leaves and grass.
Time to take a soil sample
The accuracy of the analysis also depends on time. A soil sample should be taken in early spring or late autumn, that is, before or after the growing season of plants. If the sample is taken in the spring, this must be done before applying fertilizers; if in the fall, then after at least 2 months have passed after the last application of fertilizers and before they are applied for autumn digging.
