Karyopteris - there is nothing simpler and more beautiful. How to normalize the acid-base balance of the soil? How to make soil alkaline at home

Soil acidity is an important agrochemical parameter that characterizes the suitability of the substrate for growing certain crops. Beginning gardeners often make the mistake of adjusting the pH throughout the entire plot, when it is necessary to create optimal conditions for each plant individually. Let's consider the connection between acidity levels and soil fertility and crop yields.

Regardless of soil acidity levels, the entire planet is covered in vegetation - to each his own

Soil acidity and pH indicators

Soil acidity or pH is a biochemical indicator that characterizes its ability to exhibit (neutralize) the properties of acids. During the exchange of hydrogen ions with soil minerals and organic matter, acids and bases (alkalis) are formed in the fertile layer. pH indicates their balance in the soil solution; it is designated by numbers from 1 to 14. The lower the pH number, the more acidic the environment. What determines soil acidity?

The determining factor is the original material from which the soils are formed: on sandstone, granite - more acidic, on limestone - alkaline.

A gradual increase in acidity occurs in regions with frequent heavy rainfall. Moisture, accumulating in the soil, washes minerals and salts from the root layer.

Leaching may be caused by intensive watering with low pH (acidic) water.

Acidification occurs when excessive application of plant residues, organic and mineral fertilizers to the soil.

Poor air permeability of the soil contributes to an increase in acidity. If organic matter decomposes without access to oxygen, organic acids and carbon dioxide released as a result of a chemical reaction remain in the soil.

Interesting! In the Russian Federation, approximately a third of agricultural land is acidic and requires regular liming. This is most of the soddy-podzolic, soddy and gray forest soils of the middle zone and Siberia. In Western Europe there are almost 60% of such lands.

Let's consider the optimal soil acidity indicators for plants, and below in the table we specify them in the context of garden and vegetable crops.

The most acceptable acidity level for most cultivated plants is in the range from 5.5 to 7.5 - these are slightly acidic (5-6), neutral (6.5-7) and slightly alkaline (7-8) soils. A pH below 5 means a medium to strongly acidic reaction, above 8 means an alkaline reaction. An acid-base balance above 9 indicates that we have saline-carbonate soils or even saline soils.

Optimal acidity range for common horticultural crops

Harm from excess acidity and alkalinity

Soil acidification negatively affects its fertility and negatively affects the growing season of most plants.

Due to the strong concentration of organic acids in the cells, protein metabolism is disrupted, root development slows down, and their gradual death occurs.

Excessive acidity inhibits the movement of phosphorus into the above-ground part of the plant, which provokes phosphorus starvation.

In an acidic environment, the availability of nutrients, especially phosphorus, potassium, calcium, and magnesium, decreases. But the concentration of iron, aluminum, boron, and zinc reaches a level that is toxic to the roots.

Unlike neutral soil, increased acidity of the soil inhibits the activity of beneficial microorganisms that enrich the fertile layer with nitrogen. At the same time, it provokes the growth of pathogenic microflora (fungi, viruses, pathogenic bacteria).

An excessively alkaline environment (pH>7.5–8) is no less destructive for plants. In it, most of the microelements necessary for growth (phosphorus, iron, manganese, boron, magnesium) turn into insoluble hydroxides and become unavailable for nutrition.

Signs of acidic soil

You can determine the acidity level of the soil on a site by external signs, using a special device or laboratory tests.

Signs of acidic soil on the site.

After rains, the water standing in the depressions takes on a rusty hue, a dark yellow sediment forms in it, and a rainbow film forms on the surface.

After the snow melts, a whitish or gray-green coating is noticeable on the surface.

Immediately below the fertile layer lies a podzolic horizon with a thickness of 10 cm. It can be identified by characteristic whitish spots similar to ash.

A relatively reliable indicator of acidity is wild flora. Weed plants characteristic of acidic soil are woodlice, horsetail, ranunculus, plantain, horse sorrel. Overgrown wheatgrass, sow thistle, and chamomile indicate a slightly acidic reaction.

Signs of an alkaline environment

The alkaline nature of the soil is determined by sodium salts, so the process of increasing alkalinity is also called salinization. One of the main reasons for the increase in pH above 8 is intensive irrigation in arid regions, as a result of which it floats, does not allow air to pass through well, and its porosity deteriorates.

Alkaline soil is more difficult to identify by external signs.

Among the weeds, they are preferred by field bindweed (birch), quinoa, and field mustard (colts).

Chlorosis (yellowing) of leaves often appears on garden plants and trees. This occurs due to a lack of iron, which becomes unavailable in alkaline bases.

Note! If nettles, clover, and quinoa grow happily on your site, you are in luck. This is evidence of a neutral pH reaction optimal for agriculture.

Optimal acidity for different groups of plants

Before adjusting the pH level, it is important to understand which plants like acidic and slightly acidic soil, and select a list of crops for which the acid-base balance needs to be brought to neutral. There is a group of plants that prefer an alkaline environment.

Acidic soils

In acidic and strongly acidic soil (pH<5) обычные микроорганизмы развиваются плохо, зато хорошо разрастаются микроскопические грибки. В процессе эволюции ряд растений образовали прочный симбиоз с ними. Грибница, проникая в корни растений, выступает проводником органических веществ и минералов. В свою очередь корневая система растений изменилась настолько, что получать питание другим способом уже не может.

The group of plants for acidic soil includes:

coniferous trees and shrubs;

heathers, rhododendrons, azaleas;

forsythia;

rowan, aralia;

lingonberries, blueberries, cranberries, blueberries.

In order to choose the right substrate, lovers of decorative gardening need to know which flowers like acidic and slightly acidic soil, including indoor ones.

Garden flowers include lily of the valley, ranunculus, viola, camellia, and lupine.

Indoor crops include gardenia, monstera, cycas, ferns, fuchsia. They prefer a slightly acidic environment - begonia, asparagus, violet, pelargonium, ficus.

Subacid

Soils with a pH level in the range of 5–6 units are considered slightly acidic. Plants adapted to growing in such an environment are sensitive to a lack of magnesium and iron. Increasing the acid-base balance to neutral parameters leads to the fact that crops cease to absorb these elements. Their leaves turn yellow (chlorosis), and the flowering time is sharply reduced.

Low acidity of the soil is optimal for potatoes, cucumbers, cauliflower, tomatoes, and radishes.

Flowering plants in this group include irises, primroses, lilies, roses, and gladioli.

The acidity of the soil for berry crops - strawberries, raspberries, gooseberries, blackberries - should be within these limits.

Neutral

Mineral components are well absorbed from a substrate with a pH level of 6–7 units. Soil bacteria develop in it, which in the process of life enrich the soil with nitrogen in an accessible form. This environment is resistant to fungal infections.

Neutral and slightly alkaline soils love root vegetables (beets, carrots, celery), cabbage, and onions.

Note! For legumes (peas, beans, asparagus, alfalfa), neutral soil acidity is not only desirable, but vitally important. On the roots they form nodules - bacteriosis (symbiosis of roots with bacteria), due to which they absorb atmospheric nitrogen. In an acidic environment (pH<6) бактерии не живут.

Slightly alkaline

A slightly alkaline environment has an acidity level of 7–8 units. For most cultures this is already a lot.

A slightly alkaline (but not higher!) indicator is suitable for growing fruit trees - apricot, quince, walnut, mulberry, peach.

Some deciduous plants grow well on alkaline soils - acacia, catalpa, Norway maple, hawthorn, plane tree, Japanese sophora.

Regulate soil acidity using lime (lower) and gypsum (increase) materials. But this should not be done completely, but taking into account the needs of the plant, individually, adjusting the substrate in the zone of action of the root system.

Plants that indicate soil acidity:

Soil alkalinity – the ability of soils to neutralize acidic components and alkalize water. There are actual and potential forms of silkiness.

Actual alkalinity. Actual alkalinity is associated with the presence in the soil solution of hydrolytically alkaline salts, upon dissociation of which hydroxyl non is formed:

Na 2 CO 3 + 2HOH ↔ H 2 CO 3 + 2 Na + + 2OH -

Anions of weak acids play a certain role in the formation of soil alkalinity. Almost all weak acid anions present in the soil solution can participate in the formation of soil alkalinity, forming conjugate acid-base pairs.

The real contribution of a particular compound to soil alkalinity is determined not only by the value of the basicity constant, but also by the concentration of ions in soil solutions. Usually, when characterizing the actual alkalinity of natural waters, aqueous extracts and soil solutions, total alkalinity, alkalinity from normal carbonates and alkalinity from bicarbonates, which differ in the boundary pH values, are distinguished. They are determined by titrating the extract with acid in the presence of various indicators. The results are expressed in mEq/100 g of soil. Alkalinity from normal carbonates is due to the presence of Na 2 CO 3, CaCO 3, MgCO3. Alkalinity from bicarbonates is associated with NaHCO 3 and Ca(HCO 3) 2. In most soils with an alkaline reaction, carbonates predominate, which determine the corresponding reaction of the environment. In this regard, the carbonate-calcium system and the carbonate-calcium equilibrium are distinguished. The calcium carbonate system includes CaC0 3 of the solid phase, ions in the PPC, nones of the soil solution: Ca 2+, Ca HCO 3 +, CO 3 2- OH -, H +, H 2 CO 3, as well as CO 2 of the soil solution located in equilibrium with CO 2 of soil air. This system is very mobile and includes several equilibria:

As the partial pressure of CO2 decreases, the equilibrium shifts towards the formation of CO groups. In this case, a sparingly soluble compound CaCO3 is formed, which precipitates, and the pH of the soil solution increases, since CO is a stronger proton acceptor than HCO 3 - and alkalizes the environment to a greater extent. As a result, against the background of an increase in pH, the value of carbonate alkalinity decreases. An increase in the partial pressure of CO2 leads to a decrease in pH and an increase in carbonate alkalinity as a result of an increase in solubility.
capacity of CaCO 3.

Calculations show that the pH of a solution in equilibrium with CaC0 3 of the solid phase and CO2 of the atmosphere is 8.2-8.3. When free access to CO2 is difficult, pH values ​​reach 9.8-10.0.

Potential alkalinity is due to the presence in the PPC of an exchange-absorbed sodium ion, which, under certain conditions, can pass into the soil solution with the formation of carbonates and bicarbonates, causing its alkalization. For example, when carbonic acid is formed due to plant respiration and the decomposition of organic residues, calcium carbonate transitions into more soluble bicarbonate, followed by ion exchange:

Carbonic acid can directly interact with the absorption complex of soils containing exchangeable sodium to form soda (sodium carbonate):

Soils with an alkaline reaction environment are formed in regions with a deficiency of atmospheric precipitation, where the removal of weathering and soil-forming products from soils and soil-forming rocks is limited. The alkaline reaction of the environment is typical for chestnut and light chestnut, brown semi-desert and gray-brown desert soils, gray soils of carbonate varieties of chernozems and dark chestnut soils; soda solonetzes and solonchaks are especially high in alkalinity.

High soil alkalinity is unfavorable for most crops. In an alkaline environment, plant metabolism is disrupted, the solubility and availability of phosphates, compounds of iron, copper, manganese, boron and zinc are reduced. During an alkaline reaction, substances toxic to plants appear in the soil solution, in particular soda and sodium aluminates. In the event of a sharp increase in pH, plant root hairs experience an alkaline burn, which negatively affects their further development and can lead to death. highly alkaline soils are characterized by pronounced negative agrophysical properties, which is associated with strong peptization of soil colloids and dissolution of humic substances. Such soils become structured, become highly sticky when wet and hard when dry, and are characterized by poor filtration and unsatisfactory conditions. Highly alkaline soils are infertile.

An effective method for increasing the fertility of soils with an alkaline reaction is chemical reclamation. Gypsum and various substances are widely used as an ameliorant.

When adding gypsum to alkaline soils, on the one hand, the soil solution is neutralized by the salt, and on the other hand, exchangeable sodium is displaced from the PPC:

After gypsuming soda soils, as well as in natural carbonate soils, the reaction of the environment will be at a level determined by the presence of CaCO3 and MgCO3 (pH 8.2-8.6). If it is necessary to further reduce the pH, acidic ameliorating substances are used, in particular sulfuric acid. Acidification of soda soils is a highly effective method. During acidification, not only complete neutralization of alkalinity occurs, but also the displacement of sodium from the PPC:

An important condition for effective chemical reclamation of alkaline soils is the removal of neutralization and metabolic reaction products, most often sodium sulfate. Although sodium sulfate is less harmful to plants than, for example, soda, its presence in the soil is still undesirable. In addition, reverse absorption of sodium by soil PPC is possible. To remove easily soluble sodium salts formed during chemical reclamation, soil leaching is used.

How to independently determine the type of soil on your site, and what to do with it so that it pleases you with good fertility.

Land question: why do we need to be able to determine the type of soil on which we want to get excellent yields?

The type of soil on the site worries many beginning gardeners. This question is also asked by those who have recently purchased a new plot of land and are faced with the problem of choosing fertilizers.

Very often, gardeners come across advice like “if you have acidic soil, then...”, but how do you find out what kind it is?

And here we see a real Chinese script, collected from chemical formulas, PH level indicators and incomprehensible definitions.

What does acidic, normal and alkaline soil mean?
If you measure the PH of the soil in a special laboratory, then acidic soil will have a value from 4 to 5. Alkaline soil will have a value from 7 and above, and normal soil - from 5 to 7. Moreover, in some sources, a value from 5 to 6 is called slightly acidic, and from 6 to 7 – slightly alkaline. But they are favorable for the growth of cultivated plants, so they can be combined into “normal” types of soil.

Accordingly, special substances (fertilizers) are added to acidic and alkaline soil for normalization. But what if you don’t have the opportunity to take a soil sample to the laboratory? Then focus on indirect signs that will help you determine the type of soil on your plot of land or use strips to determine PH.

Determining acidity in plants
By plants we mean wild herbs, affectionately called weeds by gardeners. For example, increased acidity of the soil is indicated by: horsetail, heather, wild rosemary, sedge, fern, plantain. Indicators of slightly acidic soils are: clover, coltsfoot, and nettle. Slightly alkaline - sedge and bindweed. Alkaline soil is favorable for field mustard, poppy and quinoa.

PH strips
If you purchase strips for determining PH, you can find out a more or less accurate indicator without laboratories. To do this, take 10 grams of earth and dilute it in 30 ml of water. As soon as a precipitate forms, place the strip. The color will indicate the PH level (what color, what it means, is indicated in the instructions).

Acidic soil
Excessive soil acidity leads to poor development of cultivated plants. The reason is a violation of nitrogen nutrition. This means that plants do not receive minerals such as phosphorus, calcium, and magnesium. Even if they are theoretically present there, the acidity prevents them from being released to feed the plants. The second disadvantage of acidic soils is unfavorable microflora, which allows fungi and other pathogenic microorganisms to quickly spread.

Normalization of acidic soil
It is better to apply the listed fertilizers and microelements in the fall, at the time when you are digging up the soil and preparing the area for winter.

So, this will help you:

Liming;

Adding magnesium;

Planting plants of the legume family - they slightly normalize the soil index;

Fertilizer with dolmite flour;

Fertilizer with chalk and wood ash.

Alkaline soil
Alkaline soil has low magnesium and iron content. Due to the lack of these substances, plants often experience early yellowing of foliage, deformed fruits, and often the death of the majority of the crop.

Normalization of alkaline soil
Alkaline soil needs to be “acidified.” On the territory of Russia, most often there are deviations towards an acidic environment, but there are exceptions. To normalize the alkaline environment use:

Fertilizers with an acidic reaction - potassium, sulfur, ammonium;

Organic fertilizers - rotted oak leaves, pine needles;

Rotten sawdust;

Addition of iron chelate.

The last point relates not so much to correcting the pH of the environment, but to replenishing the iron deficiency from which all alkaline soils suffer.

Mechanical composition
In addition to the acidity level, it is important to know another indicator - the mechanical composition.

The main types are light, heavy and loamy.

1. Light soils are rich in sand and have an “airy texture.” If you try to mold something from such soil, you will not succeed; it literally crumbles in your hands.
Their disadvantage is that they do not retain water well enough, thereby depriving the plants of some nutrients. Positive properties - they warm up quickly and have good gas exchange.

What to do?

The main task is to make light soil more dense and moisture-absorbing. To do this, it is necessary to add clay mass. Even swamp mud will do. Humus and compost also compact the soil well.

2. Heavy soils are better enriched with nutrients, have high density and moisture capacity. But this also has its disadvantages: stagnation of water after rain (which means waterlogging of crops), slow decomposition of organic matter (which means there is a possibility of nutritional deficiency).

What to do?

The task is the opposite - to loosen. Sawdust and sand will work well with it. Green manures with a developed root system, for example, cereals, will also have a beneficial effect on soil looseness.

As for loamy soils, they represent a conditional norm and do not require additional actions to loosen and compact. However, this does not mean that it does not need other fertilizers. What are the characteristics of such soil? If you try to roll a sausage out of a handful of soil, it will roll (unlike “light”), but when rolled into a ring it will crack and fall apart (unlike “heavy”).

Approach gardening work wisely and knowledgeably, and you will certainly have a good harvest! published If you have any questions on this topic, ask them to the experts and readers of our project.

In chemistry, pH is an index that shows how acidic or alkaline a certain substrate is. pH values ​​range from 0 to 14: if the pH value is approximately 0, it indicates a very acidic environment, if it approaches 14, it indicates an alkaline environment. A pH value of 7 indicates a neutral environment. In gardening and horticulture, the pH of the soil in which plants are grown can have a major impact on plant growth and health. Although most plants grow well at a pH of 6.5-7, there are some species that grow much better at certain soil acidities, so serious gardeners should learn the basics of managing soil acidity. Start with step one and you will learn how to lower the soil pH in your garden.

Steps

Part 1

Check the pH level of the soil. Before you add anything to the soil to change its acidity level, be sure to check how different the pH is from what you need. You can purchase a DIY pH test kit from a gardening supply store, or see if you can have your soil tested by a professional.

Dig 5 small holes in the area. The easiest way to determine the pH of the soil in your area is to use a special pH test kit. These kits are usually inexpensive and are available at many hardware and gardening stores. Start by taking soil samples from the area where you want to test the pH. Dig five small holes, 15-20 cm deep. The location of the holes should be random within the site - this will give you an “average” pH value for your soil. You won't need the soil you took out of the holes now.

• Please note that we are only providing very general instructions in this section - you will need to follow the instructions that came with your pH test kit.

1. Take a soil sample from each hole. So, take a bayonet or shovel and cut out a narrow “slice” of soil from the side of each hole. This "slice" should be half-moon shaped and 1/2 inch thick. Place the samples in a clean, dry basket.

   • Try to take enough soil from each hole so that the total sample volume is approximately 0.94 liters or more. For most methods this is sufficient.

2. Mix the soil in a basket and spread a thin layer on newspaper to dry. Let the soil dry until it feels dry when you touch it.

   Use the kit to determine the exact pH level of your soil. The determination method will depend on your specific test kit. For most kits, you need to place a small amount of soil in a special test tube, add a few drops of a special solution to it, shake thoroughly and let the resulting suspension settle for several hours. After a certain time, the color of the solution should change, and by comparing the resulting solution with the color chart included with the test, you will be able to determine the pH of your soil.

   • There are other soil pH test kits available, so follow the instructions that came with your kit. For example, some modern electronic devices for determining pH measure the indicator almost instantly, using a metal sample.

Part 2

1. Add organic materials. Many organic materials, such as compost, composted manure, and acidic mulches (such as pine needles), can gradually lower soil pH over time. As organic materials decompose, bacteria and other microorganisms grow and feed on them, releasing acidic byproducts. Since organic materials take a long time to decompose and change the soil, this method is well suited for long-term purposes. However, if you are looking for quick results, this method will not meet your expectations. Many gardeners choose to add organic materials to the soil annually to slowly gradually lower the soil pH.

   Add aluminum sulfate. In order to quickly lower soil pH, it is not necessary to rely on the gradual, slow decomposition of the organic substrate. On the contrary, in any gardening store you can find a wide selection of additives that quickly acidify the soil. Among these additives, you can choose aluminum sulfate - one of the fastest-acting substances. Aluminum sulfate releases acid into the soil as it dissolves, which in gardening terms means it works almost instantly. Therefore, aluminum sulfate will help you if you need to quickly lower the pH of the soil in your garden.

   Add sulfur. Another substance that is added to the soil to lower the pH is sublimated sulfur. If we compare this additive with aluminum sulfate, it is somewhat cheaper, less of it is required per unit area, but it acts somewhat slower. Because the sulfur must be absorbed by soil bacteria, which then convert it into sulfuric acid, this process takes some time. Depending on soil moisture, bacterial counts, and temperature, it may take up to several months for sulfur to begin to have a significant effect on soil acidity.

   Add granular urea coated with sulphur. Like aluminum sulfate and sulfur, soil amendments containing urea coated with sulfur can gradually increase the acidity of the mail (lower its pH). Additives containing urea act quite quickly, and the effect begins to appear 1-2 weeks after adding the substance to the soil. Sulfur-coated urea is a common ingredient in many fertilizers, so if you plan to feed your plants fertilizer, you can avoid wasting time and money on this additive and immediately choose a fertilizer that contains this substance.

   • The content of sulfur-coated urea varies depending on the type of fertilizer chosen, so carefully read the instructions for the fertilizer to determine how much of the substance will be needed for your garden needs.

2. Add other acidic additives. In addition to the additives listed above, there are many other substances that are sold both separately and as part of complex fertilizers. The amount of fertilizer and the timing of its application greatly depend on the type of fertilizer, so carefully read the instructions on the product packaging or ask for advice from a consultant at a gardening store. Here are some amendments that can lower the pH level of your soil:

   • Ammonium hydrogen phosphate
   • Copper sulfate
   • Ammonium nitrate

3. Grow plants adapted to alkaline soils. If your soil is too alkaline to grow plants that need acidic soils, growing plants that prefer alkaline soils can significantly lower the pH for almost the duration of their life. As plants grow, mature, and die, the organic substrate that gets into the soil causes bacteria to grow and the soil pH gradually decreases (the same principle applies here as when adding organic material in the form of mulch or manure). This method is one of the slowest ways to lower pH because the plants must first grow before they begin to supply organic material to the soil. Here are some examples of plants that prefer alkaline soil:

   • Some deciduous shrubs (such as lilac, rose hips, clematis and honeysuckle)
   • Some evergreen shrubs (such as boxwood)
   • Some perennials (such as chrysanthemums)

Part 3

1. Lower the soil pH for shrubs such as rhododendron or azalea. Some types of flowering shrubs, such as rhododendron and azalea, require fairly acidic soil to grow well. These plants originate from areas where there is a lot of rainfall (such as the Pacific Northwest region of the United States), and high rainfall contributes to soil acidification. For these plant species, the optimal pH value varies from 4.5 to 5.5. However, they can grow in soils whose pH reaches 6.0.

   Lower the pH for flowers such as petunia or begonia. Many brightly flowering plants, such as petunias and begonias, grow best in acidic soils. For some of these colors the acidity changes from slightly acidic before Very acidic can lead to a visible change in flower color. For example, if you grow hydrangea in an area where the soil pH level is 6.0-6.2, the plant will produce pink flowers. If you lower the pH to 5.0-5.2, then you will grow flowers with blue or purple petals.

   Lower pH levels for evergreen trees. Many evergreen conifers grow in slightly acidic soils. For example, spruce, pine and fir thrive if the soil pH level is 5.5-6.0. In addition, the needles of these tree species can be added as organic material to alkaline and neutral soils. As the needles decompose, the pH level will slowly decrease.

   Lower soil pH for certain berry crops. Probably the most famous berry plant that requires acidic soil is blueberries, which grow well in very acidic soils (ideal pH values ​​are 4.0-5.0). There are other berries that prefer acidic soils. For example, cranberries grow well at a pH of 4.2-5.0, and cloudberries, currants and elderberries grow well at a pH of 5.05-6.5.

   For ferns, you need to reduce the acidity of the soil only slightly below neutral. Most varieties of garden ferns prefer soils where the pH is slightly below 7.0. Even those that prefer alkaline soils can tolerate slightly acidic substrates quite well. For example, maidenhair, which prefers soils with a pH of 7.0-8.0, can do quite well at a pH of 6.0. Some ferns can even tolerate acidic soils where the pH level is 4.0.

   Find specialist gardening resources for a comprehensive list of plants that prefer acidic soil. The list of plants that can or prefer to grow in acidic soils is too extensive to include in this article. For more complete information, we can refer to special botanical reference books. They can usually be found in gardening stores or purchased in the special section of any bookstore. Alternatively, you can find information on the Internet. For example, the official website of The Old Farmer's Almanac magazine contains a table that shows the soil acidity preference for many plants (you can find it

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23.10.2017

When growing most cultivated plants, it is necessary to take into account many different factors: weather and climatic conditions, soil fertility, humidity, soil composition, groundwater level, etc.

High alkalinity, like increased soil acidity, can also create very unfavorable conditions for the growth and development of most crops, since they have a direct impact on the degree of penetration of heavy metals into the internal tissues of plants.

To determine the acidity of the soil, the pH indicator is used ( acid-base balance), the values ​​of which usually range from three and a half to eight and a half units. If the “pH” of the soil is neutral (within six or seven units), then heavy metals remain bound in the soil and only a tiny amount of these harmful substances enters the plants.

How to determine soil acidity and improve its “pH” can be read .

Alkaline soil has low fertility because the soil is usually heavy, viscous, poorly permeable to moisture and poorly saturated with humus. Such soil is characterized by a high content of calcium salts (lime) and elevated pH values.

According to their characteristics, alkaline soils can be divided into three main types:

· Weakly alkaline soils (pH value of about seven or eight units)

· Moderately alkaline (pH value about eight, eight and a half units)

· Strongly alkaline (pH value above eight and a half units)

Alkaline soils are very different - these are solonetz and solonetzic soils, lands that contain a large part of stony loam, as well as heavy clay soils. In any case, they are all calcareous (that is, saturated with alkali).

To determine the presence of lime in the soil, just pour a little vinegar onto a lump of soil. If lime is present in the soil, an instant chemical reaction will occur, the earth will begin to hiss and foam.

The easiest way to determine the exact “pH” value is to use litmus paper (a standard indicator specially designed for this purpose that shows the acidity of the soil). To do this, you should prepare a small amount of an aqueous solution in the form of a liquid suspension (at the rate of one part earth to five parts water), and then dip a litmus indicator into the solution and see what color the paper turns.

Some plants can also indicate the presence of alkaline soil, for example, chicory, bellflower, thyme, spurge, and woodlice.

Calcareous soils are most often located in the southern part of the steppe and forest-steppe zones of Ukraine and are alkaline chestnut and brown soils with poor vegetation. These soils are characterized by a low humus content (no more than three percent) and low humidity, therefore, in order to successfully grow crops on these lands, it is necessary to oxidize the soil and provide additional irrigation.

As for solonetzes and solonchaks, these are extremely problematic, infertile lands, which also have a high salt content. These soils are characteristic of the southern steppes, present on the sea coasts and in the coastal areas of large and small rivers in our country.

Ways to Improve Alkaline Soil

The pH value of alkaline soils can be improved through reclamation measures and the addition of calcium sulfate, which is popularly called gypsum, into the soil. When regular gypsum is added, calcium displaces the absorbed sodium, as a result of which the structure of the solonetz horizon improves, the soil begins to pass moisture better, as a result of which excess salts are gradually washed out of the soil.

The effect of adding gypsum is not limited only to increasing the amount of sulfur in the soil, since it first of all improves the structure and quality of the soil, helping to increase the content of bound sodium in it.

Granular sulfur is also used as an excellent soil oxidizer, which should be applied gradually (about twenty kilograms per hectare of area), with an interval of three or more months. But it should be remembered that the result from adding sulfur can be expected only after a year or even after several years.

To improve alkaline soil, it is recommended to perform deep plowing, but without ameliorating additives it is usually less effective.

To neutralize alkalinity caused by the presence of sodium carbonates and bicarbonates in the soil, weak solutions of various acids, most often sulfuric, should be used. A similar effect is exerted by acidic salts, which form acids due to the hydrolysis reaction (for example, iron sulfate is often used as a component for the reclamation of alkaline soils).

In practice, to improve soil alkalinity, farmers sometimes use waste from the phosphorus mining industry, that is, phosphogypsum, which in addition to calcium sulfate contains impurities of sulfuric acid and fluorine. But recently, scientists have sounded the alarm, since phosphogypsum, although it neutralizes increased alkali, also pollutes the soil with fluorine. Plants can react differently to a given substance (for example, it has been proven that high levels of fluoride in plants intended for animal feed can be quite toxic).

In slightly alkaline soils, the structure of the fertile horizon is improved by plowing with the introduction of increased doses of organic fertilizers, which acidify the soil. The best of them is rotted manure, to which you should add ordinary superphosphate (about twenty kilograms per ton of manure) or phosphorus flour (about fifty kilograms per ton of humus). To reduce soil alkalinity, you can also add peat moss or bog peat to the soil. The needles of pine trees, which are often used as a basis for mulching the soil, acidify the soil quite well. Compost made from rotted oak leaves gives a good result for normalizing alkalinity.

In arid areas with little monthly rainfall, additional irrigation is required.

Alkaline soil is significantly improved by planting green manure plants, which are an excellent source of biological nitrogen. As green manure crops, crops such as lupine (containing a large amount of protein substances) and other plants of the legume family, as well as seradella, clover, sweet clover, white mustard, rye and buckwheat are used.

When using mineral fertilizers, you should choose those that acidify the soil, but do not contain chlorine (for example, ammonium sulfate).