RU2728239C1 - Method for determining optimum dose of second nitrogen top dressing of winter cereals (winter wheat and winter barley) - Google Patents

Abstract

FIELD: agriculture.SUBSTANCE: method for determining an optimum dose of a second nitrogen fertilizer for winter cereal crops includes determining nitrogen content in plant biomass from the surveyed field, wherein the value of specific biomass of agrophytocenosis (APC) is further determined, and also take into account: amount of precipitation, which fell in March of current year, value of planned yield, dose of first nitrogen fertilizer carried out on surveyed field, content in soil of same nitrogen field of exchange ammonium (N-NHin 0–20 cm layer), movable phosphorus (PO) and exchange potassium (KO in layer of 20–40 cm).EFFECT: invention makes it possible to increase accuracy of determining the optimal dose of second nitric fertilizing of winter cereals based on weather conditions, APC state, effective soil fertility and planned crop capacity.1 cl, 3 tbl, 2 ex

Description

The invention relates to agriculture and is an element of improving the intensive technology of cultivation of winter crops (winter wheat and winter barley). It can be used to determine the optimal dose of the second nitrogen fertilization during the period of the beginning of plant stemming in fields differing in effective soil fertility, the state of agrophytocenosis (AFC), and planned yield.

The development of new, more accurate and effective methods for determining differentiated doses of nitrogen fertilizing is an urgent task, since nitrogen fertilizers occupy a significant place in the cost of crop production, especially given the tendency to increase their market value.

A known method for determining the nitrogen demand of plants of winter crops for spring feeding by calculating the difference between the amount required to obtain the planned yield, and its actual stock in a meter layer of soil. If a certain dose of nitrogen exceeds 60 kg / ha, then it should be applied in two steps: in the tillering phase (40%) and in the tubing phase (60%).

The main disadvantage of this method for determining the nitrogen demand of winter crops for spring feeding is its very high labor intensity (Agronomic notebook. Cultivation of grain crops using intensive technologies. - Moscow, Rosselkhozizdat, 1986; p. 97).

A known method for determining the dose of the second nitrogen fertilization to increase the yield and quality of winter wheat grain by tissue diagnostics. The method is as follows: one drop of 1% diphenylamine solution is applied to a thin section of the stem, placed on a glass slide, and covered with another glass, slightly pressing down, until the juice is released. The resulting color from the interaction of the juice with diphenylamine is compared with a reference color scale. In accordance with the gradations of the color scale, the need for foliar top dressing is established according to the average points, the doses and timing of fertilization are determined.

The main disadvantage of this method for calculating the dose of the second nitrogen feeding is that only one of the forms of nitrogen in plant tissues is taken into account - N-NO ₃ , especially since its level depends not only on the content of nitrates in the soil, but also on the activity of the enzyme nitrate reductase in plants, in addition, the content of other elements of mineral nutrition of plants is not taken into account. The disadvantages of this method can also be attributed to the following: the analysis is carried out only in the morning or evening hours, and the results obtained are reliable only if the plants are sufficiently supplied with phosphorus (Agronomic notebook. Cultivation of grain crops using intensive technologies. - Moscow, Rosselkhozizdat, 1986; p. 98- 99).

There is also known a method for determining the dose of the second nitrogen fertilization to increase the yield and quality of grain by means of modified tissue diagnostics - nitrate test (analogue of the method of VV Zerling). In order to obtain the necessary information for determining the doses and timing of nitrogen fertilization and assessing the effectiveness of the use of trace elements and nitrogen fertilizers, consecutive agrobiological observations were carried out: the density of seedlings of plants, spike-bearing stems and the degree of plant development were determined. During the stemming phase, the number of strong, potentially productive stems was counted.

This method of calculating the dose of the second nitrogen fertilization has a number of disadvantages, which entail an incorrect determination of the plant's need for nitrogen: it is very laborious, the assessment of the required dose of fertilizer nitrogen based on the content of N-NO ₃ in plants is not accurate, in addition, there is not enough information about plants and their needs for various food elements (Feofanov SN Abstract of the thesis for the degree of candidate of biological sciences. Regulation of winter wheat nutrition with intensive technology of its cultivation, Moscow, 1993; p. 1-18).

A known method for determining the dose of the second nitrogen feeding to increase the yield and quality of winter wheat grain by using the device N-tester (portable spectrophotometer) during the period of plant stemming.

Measurements are carried out directly on the field when passing along its diagonal at equidistant points in three replicates (30 plants in one sample) on each site with an area of 90-100 hectares. To determine the chlorophyll content (in relative units), fully developed leaves are selected. Measurements were carried out on the upper leaves (2-3 ^minutes) of different stems, giving the main preference. The middle of the sheet is inserted into the measuring head of the device and measurements are taken, the device shows the average value on the display. Further, the obtained indicators are interpreted according to a special table or graph.

The main disadvantage of this method for calculating the dose of the second nitrogen fertilization is that the readings of the device depend on many factors, in particular, on the ratio of chlorophyll forms in the leaves of a particular cultivar type, the phase of plant development, the level of plant availability with phosphorus, potassium, sulfur, the presence of water in the leaves. deficit. (Accurate application of nitrogen fertilizers. Recommendations. Use of the "N-tester" device on crops of grain crops. LLC "Hydro Agri Rus". Krasnodar, 2003; p. 6-17).

Known "Method for determining the dose of nitrogen fertilization of agricultural plants." It includes the determination of the actual level of chlorophyll content in the leaves, taking into account the varietal characteristics, with a portable device for leaf diagnostics ("N-tester"). Determine the optimal value of the level of chlorophyll content in the leaves and the number of kilograms of the active substance of nitrogen fertilizer (K), corresponding to one conventional unit of chlorophyll content in the leaves. According to, the difference between its optimal and actual values (P) is judged on the need for nitrogen fertilization, and the dose (N) is calculated by the formula: N = K × P, where: K is the number of kilograms of the active substance of nitrogen fertilizer, corresponding to one conventional unit of content chlorophyll in the leaves; P is the difference between the optimal and the actual value of the level of chlorophyll content in leaves, in arbitrary units.

The method makes it possible to increase the efficiency of determining the dose of nitrogen fertilization in the field.

The main disadvantage of this method is the lack of accounting for the content of such elements of mineral nutrition in plants as phosphorus, potassium and sulfur, which significantly affect the concentration of chlorophyll in plant leaves, and their ratio N: P: K: S ultimately determines the N- tester.

In addition, due to the frequent change of varieties, the experience in determining varietal amendments will have to be conducted constantly, which significantly increases the complexity of this method (http://www.findpatent.ru/patent/245/2453097.html © Find-Patent.ru - patent search, 2012-2016).

A known method for determining the dose of the second nitrogen fertilization to increase the yield and quality of grain by determining the concentration of amino acids in the juice of the leaves. Spring soft wheat varieties Moskovskaya 35 were grown under different regimes of plant nutrition with nitrogen, phosphorus and potassium; in the tube exit phase in the leaf juice, the concentration of amino acids forming colored compounds with the Folin reagent was determined, which was used to estimate the total concentration of all proteinogenic amino acids simultaneously consumed for the synthesis of structural and functionally active proteins. In mature wheat kernels, the total protein content was determined, which is the main indicator of grain quality.

A significant drawback of the method is its laboriousness, as well as incomplete information about plants and their need for nutrients, lack of complete information about effective soil fertility (plant physiology, microbiology, issue No. 5. A new method for diagnosing nitrogen nutrition and predicting the quality of wheat grain. 2017; p. 29-38).

A known method for determining the dose of the second nitrogen fertilization to increase the yield and quality of winter wheat grain by determining the content of gross nitrogen in plants and soil, taking into account the weather conditions of the area. The basis of this method is to use new levels of nitrogen in winter wheat plants that are significantly different from previously established ones. If earlier it was recommended to apply late foliar nitrogen fertilizing in the presence of 3.5-4.0% nitrogen in plant leaves, now the authors recommend 2.0-3.0%.

The main disadvantage of this method is the lack of an accurate description of the method for calculating the dose of the second nitrogen fertilization, aimed at increasing yields. At the same time, other necessary plant nutrients are not taken into account, the exact phase of sampling for analysis is not known. In the article, the authors talk about increasing the yield and quality of grain, but do not specify what exactly their method is aimed at (Agriculture, issue No. 8. Nitrogen fertilizing of winter wheat plants in the conditions of the Stavropol Territory. 2017; p. 18-20).

Also known "Method for determining the dose of the second nitrogen fertilization of winter crops" according to the level of nitrogen in the biomass of plants and the density of agrophytocenosis during the period of steming - the prototype. It consists in determining the total nitrogen content in the aboveground plant biomass and the actual density of APC at the V-VI stage of organogenesis. The calculation is made according to the formula:

D is the dose of the 2nd nitrogen fertilization, kg a.i. / ha; N _opt ,% - the optimal nitrogen content in the aboveground biomass of plants (N _opt for winter wheat - 4.0%; for winter barley - 3.8%); N _fact ,% - actual nitrogen content in plant biomass. An amendment for the density of the stalk, which is determined according to a special table, is added to the estimated dose of feeding.

The main disadvantage of the prototype (like all previous analogues) is the low level of accuracy in determining the optimal dose of the second nitrogen fertilization of winter crops during the period of their onset of stalking (determination ~ 30-35%). In addition, the dose of top dressing is not related to the planned yield and the content of nutrients in the soil, and "N opt." (for both crops) depends on the specific biomass of the APC at the time of analysis and the variety type, that is, it is not a real constant. ("Rational system for determining the dose and timing of nitrogen fertilization on winter crops in the spring." Recommendations. KNIISH. - Krasnodar, 2017; p. 10-11).

The inventive method is based on the multiple nonlinear regression dependence of the optimal dose of the second nitrogen fertilization of winter cereal crops on the level of effective soil fertility in the spring, the specific biomass of the APC during the onset of steming (V-VI stages of organogenesis according to Kuperman F.M. ), and the gross nitrogen content in it (in% per dry matter), the dose of the first nitrogen fertilization, the amount of precipitation in March and the planned yield.

The objective of the invention: increasing the efficiency of cultivation of winter crops.

The purpose of the invention is to improve the accuracy of determining the optimal dose of the second nitrogen fertilization of winter crops, taking into account weather conditions, the state of the AFC, effective soil fertility and the planned yield, as well as increasing the payback of nitrogen fertilizers.

This goal is achieved by the fact that in the known method, including the determination of the nitrogen content in the biomass of plants from the surveyed field, according to the invention, the value of the specific biomass of the APC is additionally determined, the planned yield and the dose of the first nitrogen fertilization carried out in this field, the amount of precipitation that fell in March of this year, the content of exchangeable ammonium nitrogen (N-NH ₄ in the 0-20 cm layer), mobile phosphorus (Р ₂ О ₅ ) and exchangeable potassium (К ₂ О in the 20-40 cm layer) in the soil of the same field, and the optimal dose of the second nitrogen fertilization of winter crops is calculated by the formulas:

a) for winter wheat:

b) for winter barley:

Y is the dose of the second nitrogen fertilization, kg of nitrogen in a.i. / ha,

d _n = x _n - K _n (the difference between the value of each factor and the value of its constant),

x - factor,

K - factor constant (average long-term factor level),

x ₁ - dose of the 1st nitrogen fertilization, kg a.i. / ha,

x ₂ - specific biomass of APC (at the V-VI stage of organogenesis), g / m ² ,

x ₃ - nitrogen content in biomass,%,

x ₄ - the content of N-NH ₄ in the soil in the spring (layer 0-20 cm), mg / kg,

x ₅ - the content of P ₂ O ₅ in the soil in the spring (layer 20-40 cm), mg / kg,

x ₆ - the content of K ₂ O in the soil in the spring (layer 20-40 cm), mg / kg,

x ₇ - the amount of precipitation in March of the current year, mm,

x ₈ - planned yield, kg / ha,

at the same time, if the first nitrogen fertilization in the surveyed field was not carried out or its dose was calculated without taking into account the effective soil fertility, then additionally soil samples are taken [near the counting sites from which plants are taken (at a distance of 2-5 meters)] from two horizons - 0-20 cm and 20-40 cm, agrochemical analysis of the soil for the content of N-NH ₄ in it (from the 0-20 cm horizon) and for the content of Р ₂ О ₅ and K ₂ O (from the 20-40 cm horizon), mg / kg according to the Machigin method, the results are used to calculate the optimal dose of the second nitrogen fertilization of winter crops.

Determination of the dose of the second nitrogen fertilization of winter crops according to the formulas specified in the application (for winter wheat and winter barley) provides an increase in the accuracy of determining the dose of fertilizing and the recoupment of fertilizer nitrogen, since it allows taking into account the influence of eight factors of the system: "soil - plants - atmosphere - man" and their interactions.

Comparative analysis of the proposed technical solution with the prototype allows us to conclude that the inventive method for determining the optimal dose of the second nitrogen fertilization of winter cereal crops differs from the known one by additional actions: selection of plant biomass from registration sites on the surveyed field, calculation of the specific biomass of the AFC and taking into account information about the planned yield, the dose of the first nitrogen fertilization, the amount of precipitation that fell in March of the current year, the content of exchangeable ammonium (N-NH ₄ - in a layer of 0-20 cm), mobile phosphorus and exchangeable potassium (P ₂ O ₅ and K ₂ O - in a layer of 20-40 cm).

Thus, the claimed technical solution meets the criterion of patentability "NOVELTY."

Investigating the state of the art in the process of conducting a patent search for all types of publicly available information in print, we did not identify technical solutions that have distinctive features of the proposed method, as well as solutions related to the systemic analysis of the effect of the set of the Declared characteristics on the dose of the second nitrogen fertilization of winter crops.

Therefore, the claimed technical solution complies with the criterion of patentability "INVENTIVE LEVEL".

The claimed technical solution also meets the criterion of patentability "INDUSTRIAL APPLICABILITY", as it can be used in agriculture. And, in addition, the description of the invention presents means and methods with which it is possible to implement the method for determining the optimal dose of the second nitrogen fertilization of winter crops in the form in which it is described in the independent claim.

The method is carried out as follows.

On the surveyed field, where the first nitrogen fertilization was carried out and the second nitrogen fertilization is supposed to be carried out, to obtain the planned harvest, the following actions are performed: determine the specific biomass of the agrophytocenosis (AFC) for which plant samples are taken [dig all the plants of the surveyed culture with roots from two registration sites (0.25 m ² ) from every 25-30 hectares], in the laboratory, the upper green part of the plant stems is separated from the lower (white underground, with roots), the green aboveground part of the plants is weighed and the specific biomass of the agrophytocenosis (AFC), g / m ² . Then, in terms of suspended biomass (~ 50 g), the content of gross nitrogen (in% per dry matter) is determined in an agrochemical laboratory.

In preparation for the calculations, already known information is used:

- about the size of the planned yield in the surveyed field;

- about the dose of the first nitrogen fertilization;

- about the amount of precipitation that fell in March of the current year (according to the data of the nearest meteorological post);

- about the level of effective soil fertility [about the content of nitrogen exchangeable ammonium (N-NH ₄ ) in it from the layer 0-20 cm, mobile phosphorus (Р ₂ О ₅ ) and exchangeable potassium (К ₂ О) from the layer 20-40 cm] from the information on calculating the dose of the first nitrogen fertilization in this field.

The dose of the second nitrogen fertilization for winter ear crops in kg of nitrogen (in a.i./ha) is calculated by the formulas:

a) for winter wheat:

b) for winter barley:

Y is the dose of the second nitrogen fertilization, kg of nitrogen in a.i. / ha,

d _n = x _n - K _n (the difference between the value of each factor and the value of its constant),

x - factor,

K - factor constant (average long-term factor level),

x ₁ - dose of the 1st nitrogen fertilization, kg a.i. / ha,

x ₂ - specific biomass of APC (at the V-VI stage of organogenesis), g / m ² ,

x ₃ - nitrogen content in biomass,%,

x ₄ - the content of N-NH ₄ in the soil in the spring (layer 0-20 cm), mg / kg,

x ₅ - the content of Р ₂ О ₅ in the soil in spring (layer 20-40 cm), mg / kg,

x ₆ - the content of K ₂ O in the soil in the spring (layer 20-40 cm), mg / kg,

x ₇ - the amount of precipitation in March of the current year, mm,

x ₈ - planned yield, kg / ha.

Examples of specific execution of the method.

1. The optimal dose of the second nitrogen fertilization for winter wheat was determined in the scientific experiment of the agrotechnological department of the Krasnodar Research Institute of Agriculture (Table 1) in 2015 on the variety "Yuka" (the predecessor of corn for grain) during the period of the beginning of steming (stage V of organogenesis according to Kuperman F.M. .).

At the beginning of April, on those variants of the experiment, where the first nitrogen fertilization was carried out and the second was planned, plant samples (from the ^1st and ^3rd replicates) were taken from the registration plots of 0.25 m ² from each plot, the plants were cleared of the ground, placed in plastic bags with a label and delivered to the laboratory;

- in the laboratory, with scissors, they cut off the upper green part of the plant stems from the lower (white underground, with roots);

- weighed the green aboveground part of the plants and determined the specific biomass of the APC; it turned out to be equal to 750 g / m ² ;

- further, a part of the suspended biomass (~ 50 g) was taken for analysis for the content of total nitrogen in it;

- in the agrochemical laboratory in this biomass, the content of gross nitrogen was determined (in% per dry matter); it turned out to be equal to 2.99%.

In addition, in preparation for calculating the optimal dose of the second nitrogen fertilization of winter wheat, the information already known to us was used:

- about the level of the planned yield in the experiment - 75 kg / ha;

- about the dose of the first nitrogen fertilization - 50 kg a.i. / ha;

- about the content in the soil of the experimental site: exchangeable ammonium nitrogen (N-NH ₄ ) - 6.5 mg / kg; easily assimilated phosphorus (P ₂ O ₅ ) - 70 mg / kg; exchangeable potassium (K ₂ O) - 514 mg / kg.

- about the amount of precipitation that fell in March 2015 (according to the meteorological post KNIISH) - 35 mm.

The optimal dose of the second nitrogen fertilization of winter wheat was calculated by the formula:

Y is the dose of the second nitrogen fertilization, kg of nitrogen in a.i. / ha;

d _n = x _n - K _n (the difference between the value of each factor and the value of its constant);

x - factor;

K - factor constant (average long-term level of the factor);

x ₁ - dose of the 1st nitrogen feeding, kg a.i. / ha; (K ₁ = 50.3);

x ₂ - specific biomass of APC (at the V stage of organogenesis), g / m ² ; (K ₂ = 856);

x ₃ - nitrogen content in biomass,%; (K ₃ = 3.45);

x ₄ - the content of N-NH4 in the soil in early spring (layer 0-20 cm), mg / kg; (K ₄ = 6.8);

x ₅ - the content of P ₂ O ₅ in the soil in early spring (layer 20-40 cm), mg / kg; (K ₅ = 49.4);

x ₆ - content of K ₂ O in the soil in early spring (layer 20-40 cm), mg / kg; (K ₆ = 380);

x ₇ - the amount of precipitation in March, mm; (K ₇ = 78);

x ₈ - planned yield, kg / ha; (K ₈ = 66.2).

As a result of the calculation, it was found that the second nitrogen fertilization calculated by the inventive method should be 49 kg a.i. / ha, in fact, 50 kg of nitrogen was added to a.i. / ha, which in terms of ammonium nitrate is 145 kg f.w. / ha.

The biological yield on this variant of the experiment turned out to be equal to 72.4 c / ha, while according to the prototype, the dose of the second feeding was 38 kg a.i. / ha, and the yield was 66.5 c / ha, which is 5 , 9 kg / ha less (Table 1).

The payback of the yield increase from the second nitrogen fertilization of winter wheat, the dose of which was calculated by the method we proposed, turned out to be very good and amounted to 49.2 kg of grain / 1 kg of fertilizer nitrogen (Table 1).

2. The optimal dose of the second nitrogen fertilization for winter barley was determined in a joint scientific experiment of the agrotechnological department and the department of selection and seed production of barley of Krasnodar Research Institute of Agriculture (Table 2) in 2016 on a promising variety (selection of KNIISH) "Serp" (predecessor - peas) during the beginning of stemming (at the VI stage of organogenesis according to FM Kuperman).

On those variants of the experiment, where the first nitrogen feeding was carried out and the second was planned, plant samples were taken (from the 2nd and 3rd field replicates) from the registration plots (0.25 m ² each) from each plot, placed in plastic bags with a label and delivered to laboratory;

- in the laboratory, with scissors, they cut off the upper green part of the plant stems from the lower (white underground, with roots);

- weighed the green aboveground part of the plants and determined the specific biomass of the APC; it turned out to be equal to 1062 g / m ² ;

- further, a part of the suspended biomass (~ 50 g) was taken for analysis for the content of total nitrogen in it;

- in the agrochemical laboratory in this biomass, the content of gross nitrogen was determined (in% per dry matter); it turned out to be 2.85%.

In addition, in preparation for calculating the optimal dose of the second nitrogen fertilization of winter barley, the information already known to us was used:

- about the level of the planned yield in the experiment - 87 c / ha;

- about the dose of the first nitrogen fertilization - 40 kg a.i. / ha;

- about the effective fertility of the experimental site [the content of nitrogen exchangeable ammonium (N-NH ₄ ) in the soil - 4.5 mg / kg; easily assimilated phosphorus (P ₂ O ₅ ) - 25.0 mg / kg; exchangeable potassium (K ₂ O) - 268 mg / kg], as well as:

- about the amount of precipitation that fell in March 2016 (according to the meteorological post KNIISH) - 33 mm.

The dose of the second nitrogen fertilization of winter barley was calculated using the formula:

Y is the dose of the second nitrogen fertilization, kg of nitrogen in a.i. / ha;

d _n = x _n - K _n (the difference between the value of each factor and the value of its constant);

x - factor;

K - factor constant (average long-term level of the factor);

x ₁ - dose of the 1st nitrogen feeding, kg a.i. / ha; (K ₁ = 31);

x ₂ - specific biomass of APC (at stage VI of organogenesis), g / m ² ; (K ₂ = 1448);

x ₃ - nitrogen content in biomass,%; (K ₃ = 2.31);

x ₄ - the content of N-NH ₄ in the soil in early spring (layer 0-20 cm), mg / kg; (K ₄ = 6.4);

x ₅ - the content of P ₂ O ₅ in the soil in early spring (layer 20-40 cm), mg / kg; (K ₅ = 28.6);

x ₆ - content of K ₂ O in the soil in early spring (layer 20-40 cm), mg / kg; (K ₆ = 355);

x ₇ - the amount of precipitation in March 2016, mm; (K ₇ = 60);

x ₈ - planned yield, kg / ha; (K ₈ = 76.2).

As a result of the calculation, it was found that the second nitrogen fertilization of winter barley should be 45.2 kg a.i. / ha, in fact, 45 kg a.i. / ha, or 158 kg of ammonium nitrate in f.w. / ha were added. ... After harvesting winter barley on the variant of the experiment where the claimed method was used, a biological yield of 93.4 c / ha was obtained (Table 2), while according to the prototype, the dose of top dressing turned out to be 35 kg a.i. / ha, and the yield was 83.1 c / ha.

As follows from the presented results of the experiment (Table 2), the application of the proposed method for calculating the dose of the second nitrogen fertilization on winter barley contributed to a significant (by 10.3 c / ha) increase in its yield compared to the prototype, while the nitrogen consumption of fertilizers increased by only 10 kg of ae / ha, and its payback turned out to be very high - 103.0 kg of grain / kg of nitrogen of ae. fertilizers. All this indicates the high efficiency of the proposed method.

In addition, we have determined the significance of the factors that determine the dose of the second nitrogen fertilization of winter crops in the calculation of the prototype and the claimed method (Table 3).

As follows from this table, the total significance of factors determining the accuracy of determining the dose of the second nitrogen fertilization of winter crops according to the claimed method is almost three times higher than according to the prototype, which indicates a significant advantage (95.0; 98.1 and 34, 0% respectively) of the proposed method.

Comparative analysis of the results of experiments both for winter wheat (Table 1) and winter barley (Table 2) convincingly speaks of the advantage of the "Method" we declare.

So, as follows from the above, the use of the claimed method for determining the optimal dose of nitrogen fertilization of winter crops during the stalking period makes it possible to increase the accuracy of its determination and the payback of nitrogen fertilizers, which makes it possible to achieve the set goal and solve the problem.

Claims (24)

1. A method for determining the optimal dose of the second nitrogen fertilization of winter cereal crops, including determining the nitrogen content in the biomass of plants from the surveyed field, characterized in that it additionally determines the specific biomass of agrophytocenosis (AFC), and also takes into account: - the amount of precipitation in March this year; - the size of the planned yield; - the dose of the first nitrogen fertilization carried out on the surveyed field; - the content in the soil of the same field of nitrogen of exchangeable ammonium (N-NH ₄ in the 0-20 cm layer), mobile phosphorus (Р ₂ О ₅ ) and exchangeable potassium (К ₂ О in the 20-40 cm layer), and the optimal dose of the second nitrogen fertilization of winter crops is calculated by the formulas: a) for winter wheat:

b) for winter barley:

Y is the dose of the second nitrogen fertilization, kg of nitrogen in a.i. / ha, d _n = x _n - K _n (the difference between the value of each factor and the value of its constant), X Factor, K - factor constant (average long-term factor level), x ₁ - dose of the 1st nitrogen fertilization, kg a.i. / ha, x ₂ - specific biomass of APC (at the V-VI stage of organogenesis), g / m ² , x ₃ - nitrogen content in biomass,%, x ₄ - the content of N-NH ₄ in the soil in spring (layer 0-20 cm), mg / kg, x ₅ - content of Р ₂ О ₅ in the soil in spring (layer 20-40 cm), mg / kg, x ₆ - the content of K ₂ O in the soil in spring (layer 20-40 cm), mg / kg, x ₇ - the amount of precipitation in March of the current year, mm, x ₈ - planned yield, kg / ha. 2. The method according to claim 1, characterized in that if the first nitrogen fertilization in the surveyed field was not carried out or its dose was calculated without taking into account the effective soil fertility, then before calculating the optimal dose of nitrogen fertilization carried out during the period of stalking of winter crops, the following actions are performed : - soil samples are taken from two horizons - 0-20 cm and 20-40 cm [near the counting sites from which plants are taken (at a distance of 2-5 meters)]; - an agrochemical analysis of this soil is carried out for the content of N-NH ₄ in it (from the 0-20 cm horizon) and for the content of P ₂ O ₅ and K ₂ O (from the 20-40 cm horizon), mg / kg by the Machigin method, and the results of the analysis are used to calculate the optimal dose of nitrogen fertilization of winter crops.