Alkaline soils: identifying, improving properties and correcting problems. How to Lower Soil pH What Vegetables Grow in Alkaline Soil

The composition of the soil largely determines the normal vegetation of plants throughout the season and a bountiful harvest in the fall. The ratio of acidic and alkaline components is especially important. Depending on the pH value, all soils are divided into three large groups: alkaline, neutral and acidic. For the vast majority of crops, areas with a neutral or slightly alkaline reaction are most preferable. Unfortunately, reality does not always correspond to the wishes of gardeners, who often have to take additional measures to achieve the required level of acidity. In particular, in areas that are too alkaline or too acidic, plant growth and development are significantly slowed down due to poor absorption of nutrients. In this regard, it is necessary to regularly carry out liming activities on the site.

Signs of acidic soils

Before you begin to carry out alkalization activities, you should make sure that the soil on your site has a pH level below 6.5. How to do it? There are several methods, both scientific and folk.

• The most accurate acid-base balance of your site can be determined by sending soil samples from different points to a special laboratory. But such analysis costs money and is not always available.
• You can set up a mini-laboratory right at home. To do this, you need to purchase a kit to determine the level of soil acidity and carry out testing according to the attached instructions.
• Another home option is to buy special litmus paper and prepare a soil solution by mixing 20 grams of soil in 50 grams of water. Dip the indicator strip into the solution. If it acquires a reddish tint, then the soil reaction is acidic, and if it turns green, it is neutral. Blue color indicates an alkaline reaction.
• If you have just acquired a plot of virgin land for use, it is easy to determine the acidity by the plants covering it. On acidic soils, horsetail, coltsfoot, sedge and sorrel predominate.
• There are other home remedies for testing. Prepare an infusion of equal parts of currant and bird cherry leaves. A pinch of acidic soil dropped into this composition will turn it pink: the more intense the shade, the lower the pH value. You can approximately determine the acidity level by observing the color of the beet tops. On alkaline and neutral soils, the leaves of this crop become green, but the redder they are, the lower the pH value.

How to change the acid-base balance

Too acidic soils inhibit plant development. This happens due to excess iron, manganese and aluminum, which tend to accumulate, and also because acidification prevents beneficial microorganisms and worms from multiplying. Therefore, in soils with a low pH value, it is difficult for fruit, berry and vegetable crops to absorb calcium and magnesium.

To increase the fertility of acidic soils, they are regularly limed with slaked lime, dolomite flour, crushed chalk, wood ash and other materials. The frequency of treatment, depending on the mechanical composition of the soil, varies from 3–4 years for sandy soils, to 5–6 years for clays and loams.

As a result of liming, the nutritional value of soils increases and plants begin to better absorb substances useful for growth: nitrogen, calcium, phosphorus, molybdenum and magnesium. For liming to work properly, some prerequisites must be met:

• Alkalinization activities should be carried out regularly. The interval depends on the mechanical composition of the soil.
• When applying lime fertilizers, you need to pay attention to the presence of such an important element as magnesium. It is the optimal balance of calcium and magnesium that is the key to the successful development of plants after liming the soil, since in the absence of the latter the positive effect of lime will be neutralized. If the fertilizer does not contain magnesium, then it must be added additionally.
• The effectiveness of liming is significantly increased by organic and mineral fertilizers. Manure, potash and boron fertilizers, as well as superphosphate will be especially useful.
• It should be noted that only acidic soils with a pH below 5.5 need liming, but on slightly acidic and neutral soils the effect of such measures will be very weak. In addition, liming is necessary to improve the health of soils after their technogenic pollution, even if, according to other indicators, they are quite suitable for growing plants and obtaining a good harvest.
• The dose of lime always depends on two main indicators: pH level and soil structure. The more acidic the soil, the more fertilizer is required, but at the same pH value, heavy loams and clays need more CaCO3. At a pH below 4.5, for light soils the dose of fertilizer should be 8–9 kg per hundred square meters, and for heavy soils – 9–12 kg, and at a pH of about 5 – already half as much.
• A single application of a full dose of CaCO3 works most effectively. However, if necessary, you can divide the total amount into several doses, adding at least half the first time.
• The timing of liming coincides with the autumn or spring digging of the soil. The effectiveness of the event increases with the simultaneous application of mineral fertilizers and organic matter, and you should always start with CaCO3.
• It is better to use crumbly (without lumps) fertilizer, and carry out activities in calm and dry weather.

Heathers and ferns, lingonberries and blueberries, hydrangeas and rhododendrons grow in your garden. In this case, in addition to generally accepted agrotechnical care techniques, you need to know how to acidify the soil. For many, including the above plants, the acidic reaction of the soil solution (pH<5,5) – важнейшее условие жизнедеятельности и здоровья. Чем это обусловлено, в каких ситуациях и как увеличить кислотность почвы, рассмотрим в этой статье.

Reasons for soil acidification

The vast majority of garden and vegetable crops prefer a neutral or slightly acidic soil reaction. In numerical terms, this is the pH range from 5.5 to 7.5 units. Acidification of the soil is required if the pH is beyond the upper limit of the fork (>7.5) or the plant needs an environment that is more acidic than that available on the site to grow.

Why don't crops like alkaline soil?

Saline soils formed on a limestone base in arid steppe and forest-steppe regions have an alkaline reaction. They often border on southern chernozems; their mechanical composition is clayey or loamy. A pH of the environment above 7.5–8 units has an adverse effect on fertility and agrophysical properties.

• As a result of the alkaline reaction, such important trace elements as iron, manganese, boron, phosphorus, zinc turn into insoluble hydroxides and become unavailable for nutrition. In this case, even organic matter and mineral fertilizers do not help - the plants feel a lack of vitamins in the alkaline soil, their growth slows down, and they acquire a yellowish tint (leaf chlorosis).
• Water-physical properties deteriorate. When dry, the substrate is too dense and poorly aerated; after rain or watering, it becomes viscous and floats.

When working with alkaline soil, the first thing to do is loosen it and bring the acidity to neutral levels. Let's look at how below.

Note! Take your time to acidify the soil under fruit trees - apricot, peach, mulberry, quince. They prefer a pH around 7-8 units. Some ornamental plants do not like an acidic environment - maples, hawthorn, honey locust, plane tree, clematis, peonies.

When is neutral soil not suitable?

Neutral soil is considered to be one in which acids and alkalis are maximally balanced and neutralize each other. This is the optimal environment for the development of beneficial soil microflora and the absorption of nutrients by plants. Ideal for growing most root vegetables and legumes.

Neutral acidity of the soil can be a reason for acidification if it is necessary to create conditions for crops that require a slightly or moderately acidic environment. Potatoes need slightly acidic soil (pH between 5 and 6). Taking into account the fact that, as a rule, a large plot of the garden is allocated for this crop, it makes sense to lower the neutral acidity by 1–1.5 units, which will ensure better absorption of nutrition and increase productivity.

A slightly acidic soil environment is a guarantee of potato health

What plants like acidic soil and why?

Acidophilic plants are fans of medium and strongly acidic soils. Their natural habitat is wetlands, peat bogs, and coniferous forests.

Over the years of evolution, the root system of plants has adapted to absorb nutrients from an aggressive soil environment. A distinctive feature of acidophytes is the absence of suction root hairs. They are replaced by microscopic fungi that penetrate into the root tissue and act as a supplier of moisture and microelements. This symbiosis in botany is called mycorrhiza - mushroom + rhizome (rhizome). They cannot live and develop normally without each other, and the condition for the existence of the mycelium is an acidic environment.

Gardening and decorative acidophytes

The group of gardening and ornamental plants that need soil acidification is quite extensive:

• shrubs – heathers, azaleas, rhododendrons, wild rosemary;
• conifers - spruce, pine, juniper, fir;
• berry crops – cranberries, blueberries, blueberries, lingonberries;
• perennials - primroses, gravilat, dicentra, ferns.

Indoor decorative acidophytes

Many indoor plants come to us from tropical and subtropical regions. Heat and high levels of humidity provoke rapid decomposition of organic matter and a predominantly acidic soil environment. This determines which flowers love acidic soil, including indoor crops. Among those who prefer a pH in the range of 4.5–5 units are azaleas, camellias, fuchsia, monstera, and cyclamen. Saintpaulias (violets), representatives of the large myrtle family, love acidic soil.

The substrate for indoor plants of this group is prepared on the basis of peat, plant compost obtained from rotted pine and leaf (preferably oak) litter. Sphagnum moss is added as an acidifier.

Note! High-moor peat is suitable for acidification. Its distinctive feature is brown color. Lowland peat has a higher degree of humification and is much darker.

Methods for soil acidification

There are several ways to make the soil acidic. Which substance (material) to use as an acidifier depends on a number of factors:

• soil structure and mechanical composition;
• the initial pH of the soil solution;
• speed of obtaining results;
• acidification areas.

Let's look at the most effective options.

Organic materials

The following organic materials give an acidic reaction:

• high peat;
• rotted pine litter, sawdust;
• leaf compost;
• sphagnum moss;
• fresh manure (acidic reaction due to excess nitrogen).

Organics are suitable for acidifying loose, well-aerated, permeable substrates. As practice shows, it acidifies the soil slowly as it decomposes, but it starts this process for a long period. An additional advantage is the preservation of a loose structure, enrichment with humus and mineral nutrients. Adding 10 kg of humus or 3 kg of fresh manure per 1 m² increases the acidity per pH unit.

Advice! To use organic matter effectively, it should be placed in the root zone of the plant, and not scattered around the site. For planting, prepare an acidic substrate, which is placed in the hole. Subsequently, organic materials are used to mulch the tree trunk circle.

This method is not suitable if you need to achieve quick results.

Mineral compounds

Acidification of heavy clay soils is more effective with the help of minerals.

• Colloidal sulfur. Used when you need to change the acidity significantly - adding 1 kg of granular substance per 10 m² reduces the pH by 2.5 units. It is recommended to apply sulfur before winter, to a depth of 10–15 cm. Chemical processes with this element start gradually, so the result will be in 8–12 months.
• Iron sulfate. The substance acts softer, but faster. If you carry 0.5 kg of powder per 10 m², within a month the pH value will decrease by one, and accordingly the acidity will increase.
• If the substrate needs to be slightly acidified, use ammonium nitrate (in spring), ammonium sulfate (for autumn digging), and potassium sulfate (in autumn).

Note! Some mineral fertilizers are used, on the contrary, to deoxidize the soil. This effect is produced by calcium nitrate and sodium nitrate.

Acid solutions

Acid solutions are used if you need quick results.

• The best option is sulfuric acid or unused electrolyte (diluted H₂SO₄). 50 ml of electrolyte is diluted in 10 liters of water, the resulting volume of solution is used per 1 m² of crop area.
• Citric acid is taken in the proportion of 1–2 teaspoons of a crystalline substance per bucket of water.
• 9% vinegar is also used - 100 ml per 10 liters of water. But this is the worst option - the effect is short-lived and destroys the soil microflora.

Green manure

Once the acid-base balance is adjusted to the needs of the crop, it must be maintained in optimal condition. In this case, the pH is adjusted with acidic organic fertilizers. A good option is to plant green manure that acidifies the soil. Incorporation of green fertilizer into the soil and rotting of the root system provides plants with available nitrogen and acts as a light acidifier. Such green manures include white mustard, rapeseed, oats, colza; legumes such as lupine, soybean, and vetch are effective in maintaining pH balance.

How to acidify blueberries:

The magnificent wrinkled rose (Rosa rugosa) thrives in alkaline soil. Sometimes it grows and can form a low hedge.

Gardeners who have the opportunity to cultivate magnificent rhododendrons and other garden plants that prefer acidic soil consider themselves very lucky. However, if you look at the list of species that grow well in alkaline soil, you will be surprised to find that there are no less of them than calcephobes. By creating thoughtful compositions from them, you can design a garden that will be no less beautiful than the one in which plants from acidic soils are planted.

Plants that prefer alkaline soil, with a pH of 7.0 or higher, are called calciphiles. Use a soil acidity test kit to find out how the soil in your garden reacts.

When choosing plants to decorate an area with alkaline soil, you will be surprised to find that both trees and shrubs will grow well on it, including clematis, honeysuckle, rowan and viburnum, which love such conditions.

Clematis does well in alkaline soil.
Honeysuckle in bloom is also a calcephile.
Rowan also grows well in alkaline soil.
Viburnum in bloom will decorate your garden.
Viburnum is also good in the fall.

Flax Linum narbonense is a charming perennial that displays blue or dark blue flowers in summer. It prefers light soil. To these can be added herbaceous perennials, as well as members of the legume family, such as cistus, gorse, honey locust, sweet pea and black locust.

In some areas the soil layer is very thin, barely covering the massive limestone outcrops. Of course, in such conditions, gardening turns into hard work. After all, even planting plants can be very difficult, and the roots of the seedlings simply have nowhere to develop. Due to these reasons, there are few trees in gardens. However, some tree species, such as European beech (Fagus sylvatica), are capable of forming shallow but widely branched root systems and adapt to the almost complete absence of soil.

Such a thin soil layer can hold very little moisture during dry periods, so its upper part dries out greatly. However, plants adapted to such living conditions have roots that penetrate even soft stones.

During rare rains, they absorb quite a lot of moisture before it seeps through the soil and goes into the rocky layer. It is best to apply organic fertilizers immediately after heavy rainfall.

Typically, the soil reaction on a site is not the same. There are always places on it where it is more alkaline than in other parts. This is usually due to the accumulation of construction debris - for example, near the walls of a house or patio.

This situation is especially common in urban gardens, where fences are often made of stones held together with lime mortar. This solution can quickly turn acidic soil into distinctly alkaline soil. In this case, plants that can grow only in acidic soils should be moved, and calciphilous species should be planted in their place. This could be, for example, clematis.

However, in this case, you should remember that their roots must be protected from the hot sun. Typically, gardeners avoid replanting plants, especially in the summer. These fears are in vain: if you dig up a bush or tree with a large lump of earth and place it in a deep and wide planting hole. in most cases, they tolerate the transplant procedure quite satisfactorily.

Completely depends on the presence of alkaline elements in it. Depending on this parameter, soil can be of three types. There are acidic, alkaline and neutral soils. Despite the fact that some representatives of the plant world love soil with a high level of this indicator, such soil is the least preferable.

Acidity index

Soil acidity is a certain property that depends on the concentration of hydrogen ions. It is designated as the pH of the solution, that is, the liquid phase of the soil itself. The value is expressed in gram equivalents per liter.

Acidic soil (as defined above) is characterized by a pH value below seven, that is, the number of H+ ions is less than OH- ions (with a neutral reaction, their number is equal, which is expressed by the number 7).

How to determine acidity?

It is quite easy to set this indicator at home. To do this, in a specialized store you need to buy a kit for measuring soil acidity, which includes a certain number of litmus papers. In addition, you need to prepare a so-called soil extract (add five parts of water to one part of the soil). The container with this extract needs to be shaken thoroughly and left alone for a while to allow it to settle. Now you can place litmus paper in the liquid that is located above the sediment. Upon contact with liquid, it changes its color, which is compared with the template.

Acidic soil, the symptoms of which are described in this article, is characterized by the following colors on a piece of paper: green, blue-green and blue.

What plants indicate acidic soil?

Acidic soil (how to determine it at home is indicated above) is loved by many plants, despite the fact that its presence in the garden or personal plot can cause many problems.

Plants that live exclusively on such soils are called acidophiles. Knowing which wild herbs love such soil, you can determine acidity without chemical tests. On such soils the following most often grow:

• horsetail;
• small sorrel;
• caustic buttercup;
• blueberry;
• sorrel;
• on slightly acidic soils you can find heather, cornflowers and ferns.

However, it is worth considering the fact that many plants are indifferent to small fluctuations in this indicator, that is, they are able to adapt to edaphic factors (the combination of the chemical properties of the soil and its physical characteristics). Therefore, for a more accurate result, it is recommended to determine the amount of alkaline elements in the soil using a litmus test.

If we talk about gardening crops, then acidic soil (its signs are very easy to remember) will not be to the taste of any of the famous representatives. It is possible for some of them to grow at a pH closer to neutral, for example, quince, various varieties of apple trees, raspberries and blackberries, as well as tomatoes, sorrel, zucchini, potatoes and pumpkin. Knowing the signs of acidic soil in the garden, improving the condition of the soil is quite easy. This is possible by adding certain substances. Among the flower representatives of the plant world, acidic soil (how to deal with it can be found in the article) is suitable for irises, delphiniums, some lilies, conifers and most roses.

Other detection methods

A special Alyamovsky device can help in determining acidity. This is a set of special reagents, the main purpose of which is to analyze soil extracts (for comparison, two extracts are taken: salt and water). It also includes an indicator, potassium chloride solution, test tubes and samples. The analysis is similar to that used with litmus strips.

There is also a device that is designed to determine the acidity of the soil, while performing several functions at once:

• determination of acidity;
• humidity;
• temperature;
• soil illumination.

There are also traditional methods. For example, using cherry or currant leaves. They need to be brewed with boiling water and then cooled. Next add some soil. The acidity of the soil is determined by the color of the liquid. If the water changes its color to red, then the soil is acidic.

How does soil acidity affect plants?

To obtain a large amount of harvest, soil acidity is a very important parameter that should be taken into account when choosing plants. This is necessary to ensure that plant nutrition is not disrupted, as well as the process of assimilation of elements necessary for full development. If unadapted specimens are planted on acidic soils, this risks nitrogen starvation, especially under unfavorable climatic conditions, in particular during rains and low temperatures. A manifestation of this is considered to be that it begins to absorb the plant from the veins, and then moves on to adjacent tissues. In order not to be confused with natural aging, remember that the latter begins with the tissues between the veins, and the veins themselves remain green for some time.

In addition, acidic soil (what grows on it is indicated above) is characterized by the transition of aluminum and iron into salts, and this can lead to the fact that plants simply cannot absorb it. A high amount of these salts in the soil can lead to the fact that calcium, potassium, phosphorus, magnesium and molybdenum practically do not penetrate into plant tissues and contribute to a decrease in yield. Other elements, such as copper, boron and zinc, also become phototoxic. Plants that are not adapted to grow in acidic soil develop poorly, root branching is suspended, the absorption of water and other nutrients is significantly deteriorated, signs of acidic soil on the site prove this.

In addition, such soil can become waterlogged, and the lower the pH level, the greater the likelihood of waterlogging.

Acidic soil: how to combat it with fertilizers?

One of the ways to quickly reduce soil acidity is to apply fertilizers. For these purposes, potassium or ammonium sulfate is usually taken; potassium chloride, sodium or superphosphate are also suitable. This is due to the fact that when the specified types of fertilizers are applied, plants growing on acidic soils receive anions, not cations. During this process, positive cations remain in the soil, which leads to its alkalization.

By using such fertilizers at regular intervals, you can ensure that the soil pH level is normalized.

If different methods indicated that you have spring? You can use a tool that is universal. It is suitable for absolutely any type of soil (if you are not sure that your garden has acidic soil, the symptoms of which are described above). And this is urea. In this case, it can be used to achieve a certain degree of alkalization of the soil.

But it is better not to use ammonium nitrate, because you can get the opposite effect.

Use of lime

The most common method of combating high soil acidity is still liming. This is due to the fact that lime is able to displace hydrogen and aluminum from fertile soil layers, replacing them with magnesium and calcium. The lower the pH, the more the soil needs liming.

This procedure consists of adding lime flour (you can safely replace it with dolomite) to a depth of no more than 20 cm. After this, fill the soil with plenty of water. The frequency of liming should be about once every 5 years (in some cases it can be done less often or more often depending on the acidity level). Clay soils require the greatest amount of applied lime, sandy soils require the least.

The advantages of this procedure are obvious:

• neutralization of soil acidity, which leads to the development of microorganisms that live in the soil and are directly involved in the formation of many plant nutrients, such as nitrogen or phosphorus;
• compounds of manganese and aluminum pass into their inactive form, as a result of which the toxic effect of these elements on plants is significantly reduced;
• the absorption of potassium, phosphorus and molybdenum is activated;
• increases the efficiency of applying other fertilizers, such as manure.

Along with the application of limestone, fertilizers enriched with boron are required, since boron and manganese compounds lose their mobility.

The safest way to reduce acidity

Acidic soil, the symptoms of which are described at the beginning of the article, will improve if green manure plants are planted on it. They are able to increase the pH value.

Such plants include:

• rye;
• oats;
• representatives of legumes;
• lupine;
• phacelia.

For this method to be effective, sowing must be done several times a year for several years in a row.

This method is considered safe, since it does not harm either microorganisms that live in the soil and suffer from large amounts of calcium and lime, or plants that will subsequently grow in this area, or groundwater.

Other remedies for acidic soil

• crushed chalk (it needs to be ground, sifted, and then added to the soil at the rate of 300 g of chalk per 1 m 2 of soil, subject to strong acidification);
• peat ash (the amount of this preparation should be significantly more than chalk);
• wood ash (suitable for sandy, sandy loam and peat soils).

How to get acidic soil

In some cases, the gardener is faced with the question not of how to reduce the acidity of the soil, but, on the contrary, how to increase it. This is due to the fact that some garden crops do well on such soils. To do this, swampy peat is used as a fertilizer, which can significantly lower the pH level.

Even if there are no particular problems with soil acidity at the moment, you still need to check it periodically. This is necessary in order to take timely measures to increase soil fertility. Knowing the signs of acidic soil in the garden makes it much easier to do this.

Alkaline soils are common in areas close to chalk or limestone. Although they may be among the most productive agricultural soils in different areas, they can become a problem in the garden. Alkaline soils are often rocky and free-draining. Therefore, added organic matter can decompose quickly, making it difficult to maintain fertility. Poor growth and yellowed leaves (chlorosis) result from plants being unable to absorb iron and manganese through their roots.

About which soils are alkaline, what to do and how to counteract them

We will discuss the negative factors on alkaline soils in our material.

1. What soils are alkaline?

Alkaline soils vary greatly from gravel to clay. The clay-like element may be mostly fine calcium carbonate, making it unsuitable for plant growth. However, when true clay is present in the soil, nutrient levels can be higher and water retention capacity greater. Alkaline soils can be identified as follows: chalky or lime-rich soils, primarily composed of calcium carbonate and are highly alkaline (they have a pH of 7.1-8.0), if the soil foams when poured into a jar of vinegar, then it contains free calcium carbonate (chalk) or limestone and rich in lime, highly alkaline soils may contain pieces of small, white stones and are often large, with sharp edges that can be easily broken. Calcareous soils contain chunks of limestone.

2. Features of gardening

Naturally, lime-rich soils contain chalk and limestone in abundance and are often associated with lowlands, grass-rich pastures and chalk and limestone forests. Very often such soils are full of stones, they can be too dry in the summer, and they are often poor in nutrients and microelements. Thus, manganese and iron can be “locked” in the soil and are not available to plants. But, this type of soil has several advantages: flooding rarely occurs on light alkaline soils due to their elevation and porosity, if well fertilized, they can be moderately fertile and ideal for growing a wide range of plants, plants of the Brassica family are less likely to suffer from the conditions growing in chalk soils.

3. What to do if the soil is alkaline

Amend the soil with plenty of organic matter to improve moisture retention and humus levels in the soil (this condition can disappear very quickly due to the nature of the soil). Chalky and calcareous soils generally allow the roots of trees and shrubs to easily find moisture, but in some cases it may be irreversible to break down the subsoil to obtain sufficient depth for planting woody plants. Apply fertilizer, use mulch with added organic matter to retain moisture, Use “green manure” to help correct nitrogen levels in the garden.