Soil Pollution Control, Lime Fertilizers

2024 Author: Sebastian Paterson | [email protected]. Last modified: 2023-12-16 13:47

Read the previous part ← Combined application of organic and mineral fertilizers

Waste, or so-called "waste" in the soil, appears during the operation of the soil, when growing plants. This rule is aimed at creating optimal conditions for plant growth and at the radical improvement of the soil through the use of fertilizers.

A certain amount of "garbage" always appears in the soil during its use. Excess "debris" is not needed and must be removed to return the soil to its original state.

Such wastes can be residues from the use of fertilizers, various excretions from plant roots, sediments from the functioning of industrial enterprises and transport, etc.

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It is known that plants do not feed on fertilizers, they absorb only those nutrients from the soil - the ions that they need, and other elements from fertilizers that are used by plants in small amounts remain in the soil as waste. When interacting with fertilizers (mechanically, physically, chemically, physicochemically and biologically), the soil acidifies, a certain excess of hydrogen ions accumulates in it, and this is already garbage.

In addition, plants, when absorbing cations NH4 +, K +, Ca ++, Mg ++, through the equivalent exchange, release hydrogen ions H + into the soil through the roots, which also acidify the soil and are also waste. In acidic soil, the solubility of compounds of aluminum, iron, manganese and a number of other elements increases strongly, up to toxic concentrations for plants. Therefore, the excess of hydrogen, aluminum, iron and manganese, as an undesirable phenomenon, must be destroyed, and this is done by liming the soil.

Among organic and mineral fertilizers, lime fertilizers occupy a special place; in addition to providing plants with calcium and magnesium, they also fight “waste” and ensure a radical improvement of the soil. They remove heavy metals, radioactive substances and toxic elements from the soil. Lime, when interacting with acid, neutralizes it, and the soil becomes neutral. At the same time, readily soluble compounds of aluminum, iron, manganese and other elements precipitate, turn into compounds inaccessible to plants, and "garbage" disappears.

A distinctive feature of plants is that they are able not only to absorb, but also to release certain substances into the environment - they are called excreta. Plants have a special process for this - excretion, the process of releasing organic and mineral substances into the external environment. Excretion - the liberation of organisms from the end products of biosynthesis is considered a biologically necessary phenomenon, since these substances are physiologically not only no longer needed by the plant, but sometimes even dangerous for itself.

But they don't have a special excretory system. Plants are freed from many harmful substances by dropping individual organs, for example, during leaf fall. It uses the sheet as a container to remove unwanted substances.

The process of excretion of plants, on the one hand, is useful, but on the other, it leads to some negative phenomena: to fatigue of the soil, to the accumulation of compounds in it in toxic concentrations. Many plants cannot grow on such soils. This forces the gardener not to place them in one place for many years in a row, not to plant them where they or their ancestors have already grown, otherwise the new plants will not take root. To combat soil fatigue, crop rotation and a fertilizer application system are used.

Therefore, it is very important to deal with soil pollution and the accumulation of debris. To do this, it is necessary to correctly apply organic and mineral fertilizers to the soil, carry out regular liming of the soil, maintaining an optimal acid-base balance in the soil. And the "garbage" will disappear by itself. Organic, mineral and lime fertilizers not only increase the content of nutrients in the soil, but also destroy the so-called "garbage".

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Liming in suburban areas is still poorly carried out. Therefore, almost all soils in our region are acidic and littered with waste. The fight against soil acidity is either not carried out at all or is carried out in violation of technology. Most often, gardeners and vegetable growers only create the appearance that liming is being carried out. They know how to sprinkle something somewhere with lime. But how to properly liming the soil is forgotten.

First, when liming, the dose is important, it should be equal to the acidity and the amount of "garbage" that has accumulated in the soil. Therefore doses of lime range from 400 to 1200 g / m². The average dose is 600-700 g, which allows you to shift the soil pH by 0.5 towards the neutral reaction, that is, from pH = 5 to pH = 5.5. For plants, this is the most favorable environment for growth and development, there will be much less "waste" in such soil.

There are two options for applying lime fertilizers: the entire dose of lime, for example, 1200 g, can be applied in one step for five years, or it can be applied every year for 300-400 g.

Secondly, when liming, the physical form of the fertilizer is important. All lime materials have a high fineness of grinding, this is necessary in order for the neutralization reaction to take place at the fastest rate, since plants cannot wait, they cannot grow in acidic soil, and they need a neutral environment right now. Each smallest particle of fertilizer enters into a neutralization reaction much faster, and liming efficiency increases.

Thirdly, the technology of this technique is also important. Lime fertilizers must always be applied for plowing and mixed well with the soil so that all soil particles come into contact with the fertilizer particles. In this case, the neutralization reaction is more successful in the entire arable horizon, and not in its individual parts.

Fourthly, the timing of the introduction is also important. The best time for application is spring, since at this time the soil has optimal moisture, it easily crumbles and is easily mixed with lime. Therefore, the neutralization reaction will take place under optimal conditions and more quickly.

Thus, to combat the accumulation of compounds undesirable for plants and soil in the soil, to create optimal acid-base conditions for plants, it is necessary to regularly use, along with the introduction of organic and mineral fertilizers, lime materials, in particular dolomite flour.

Firstly, fertilizers should always be applied to the moist root layer of the soil, and this layer is from 13 to 20 cm, that is, the depth of application of 15-18 cm is considered optimal for both fertilizers and plant roots. Secondly, it is necessary to apply fertilizers no shallower and no deeper than this optimal layer. With their deeper embedding, there will be a lack of oxygen for the successful decomposition of organic fertilizers and for the respiration of plant roots and microorganisms. In this case, organic fertilizers are poorly decomposed, and mineral fertilizers sometimes turn into acidic toxic forms.

With high moisture content of these soil layers and with abundant precipitation, nutrients can easily be washed out of this arable horizon. With a shallow incorporation, organic fertilizers decompose very quickly, rapid mineralization creates a certain excess of easily soluble compounds, which leads either to a quick waste of organic fertilizers or to the loss of elements in the form of gaseous products

Mineral fertilizers with shallow incorporation, for example, when applied for cultivation, are often irreversibly fixed by the soil, passing into compounds that are difficult to reach for plants. This is enhanced especially with the alternating moisture and drying of this layer, which happens in the warm season. At the same time, potash and ammonia nitrogen fertilizers easily penetrate into the inter-package spaces of clay minerals together with water, the clay swells quickly, and when the soil dries up, the packages of minerals shrink, potassium and nitrogen get stuck in the inter-package space and cannot get out of there for many years. Potash and nitrogen fertilizers are simply inaccessible to plants.

Phosphates from phosphorus fertilizers also precipitate faster in the upper drying horizon in the form of poorly soluble compounds and also become inaccessible to plants. Nitrogen fertilizers are quickly lost from the upper soil layers in the form of gaseous compounds - ammonia, nitrogen, nitrous gases and nitrogen gas. In these cases, only the impression is created that fertilizers have been applied, but the expected effect - an improvement in plant nutrition - does not occur, and as a result, a decrease in yield.

The effectiveness of fertilizers is always higher when they are accompanied by regular watering, good agricultural technology, soil mulching, the use of various reclamation techniques to improve the physical and chemical properties of the soil - clay or sanding with deepening of the arable horizon or other measures. Fertilizers are a food link, and agrotechnical measures will only help to improve the nutritional regime of plants and increase productivity. Reclamation measures without fertilization are ineffective, they can sharply reduce soil fertility, which is undesirable, therefore, their combined application guarantees both an increase in soil fertility and the receipt of planned crop yields.

Nutrients are well absorbed by plants only from moist soil. Therefore, regular watering will facilitate the absorption of nutrients from the soil by plants.

Mulching the soil keeps the soil moist and fertile. Under the mulch, the soil remains moist for a long time, which sharply slows down the process of fixing nutrients in the form of hard-to-reach compounds. In addition, mulch suppresses the growth of weeds, improving the availability of nutrients to the main crop, it fights well against pests and plant diseases. When mulching, gardeners spend less energy on weeding, watering and other work.

It is good to use peat, mowed grass from the lawn, sawdust, fallen leaves, and so on as mulch. In the garden, on the trunk circle, black plastic wrap, stones can be used as mulch, laying them in the form of a beautiful pattern.

The main purpose of this rule is to provide plants with good availability of nutrients throughout the growing season. Therefore, the loss of fertilizers can be very different: these are mechanical, physical, chemical, physicochemical and biological losses of nutrients.

At the first stage, that is, immediately after fertilizing the soil, all fertilizers, both organic and mineral, must be retained by the soil mechanically without loss, like peas on a sieve. Such mechanical absorption of fertilizers by the soil is a positive process, but only if it occurs according to the rules for applying fertilizers. That is, if the fertilizer is applied to the wet soil layer, if it is applied to a depth of 18 cm and applied in the physical form in which it was purchased, it was stored. But gardeners are trying to "improve" something, for example, to dissolve it in water to better "feed" the plants. If you dissolve fertilizers in water and apply them in the form of a solution, then the losses will only increase due to leaching into deeper soil layers.

The physical absorption capacity of the soil is the absorption of whole molecules of fertilizers, it depends mainly on the dispersion of the soil, on the presence of a large total surface of solid soil particles. The more finely dispersed particles in the soil, the greater their total surface, on which the absorption of fertilizers occurs. It can be positive or negative. Organic fertilizers, their alcohols, organic acids and bases, high molecular weight organic compounds and alkaline substances are positively absorbed, all of them are well kept by the soil from leaching.

For mineral fertilizers, mainly negative absorption is characteristic, that is, whole molecules of mineral fertilizers are not absorbed by the soil, they are simply pushed out of it and therefore mineral fertilizers are easily washed out of the soil and are easily lost.

Chemical absorption capacity is the ability of the soil to retain fertilizers as a result of the formation of compounds that are insoluble or hardly soluble in water. Chemical absorption depends on the acidity of the soil, on the ability of the soil to form sparingly soluble salts with calcium, iron, aluminum. Chemical absorption of fertilizers is an undesirable phenomenon for the gardener, for the soil and for plants. The loss of phosphorus fertilizers is especially high in acidic soils, which form poorly soluble phosphates with calcium, magnesium, iron and aluminum.

In neutral soils, phosphorus fertilizers do not lose their solubility and the phosphate regime in these soils will be quite favorable for plants. Intensive chemical absorption of phosphorus fertilizers must be foreseen and actively prevented by introducing them together with dolomite flour, reducing acidity, precipitating iron and aluminum in the form of insoluble salts.

The physicochemical or exchange absorptive capacity of the soil is most clearly manifested in the absorption of cations such as ammonium, potassium, calcium, magnesium and other nutrients. This is the positive ability of soil colloids to keep nutrients available to plants. Mineral and organic colloidal particles take part in the exchange absorption of cations; their total amount is called the soil-absorbing complex (AUC).

In different soils, the amount of AAC is different, most of all in clay and loamy soils, and sandy soils are poor in colloids, fertilizers are poorly absorbed in them and to a large extent washed out. Therefore, on sandy soils, losses are very high and on these soils it is necessary to apply clay and organic fertilizers in order to increase the absorption capacity of these soils and the effectiveness of mineral fertilizers.

The exchange reaction between soil and fertilizer proceeds in equivalent amounts, as many cations were introduced with fertilizers, so much cations previously absorbed by the soil were released into the soil solution. For example, 100 g of potassium chloride was added, respectively, 100 g of hydrochloric acid appears in the soil solution. The soil solution will become highly acidic, the roots of plants will not be able to live in hydrochloric acid. Therefore, the task of the gardener is to anticipate this and, together with potassium chloride, add 100 g of dolomite flour to neutralize the acid that has appeared.

The biological absorption capacity of the soil is the absorption of nutrients by the plant roots. It is very important in the application of fertilizers. Fertilizers should be applied precisely in the expectation of good absorption of nutrients by the plant roots. Therefore, fertilizers are never applied in autumn, when the plants are no longer there, there is no biological absorption. They are never applied in winter, when there are also no plants, and the snow does not need to be fertilized accordingly; they are never applied long before sowing plants, since fertilizers without growing plants can be easily washed out, become insoluble or evaporate into the air in the form of gaseous compounds.

The biological absorption capacity of the soil must be constantly maintained, that is, the soil must not be left without plants for a long time. And after harvesting the main crop, try to occupy the field with another crop so that nutrients are not lost from the soil of this field.

We hope that our tips and rules will help you avoid mistakes in summer cottage farming, let them decrease.

Gennady Vasyaev, Associate Professor, Chief Specialist of the

North -West Regional Scientific Center of the Russian Academy of Sciences, [email protected]

Olga Vasyaeva, amateur gardener

Photo by E. Valentinova