Nº 1 (2023)

In a stationary field experiment on soddy-podzolic light loamy soil, the influence of fertilizer systems (organic, mineral, organo-mineral) and liming on the balance of nutrients, changes in the agrochemical parameters of the soil and the productivity of grain-grass crop rotation was studied. At the end of the 1st rotation of the five-field crop rotation, a medium-strength correlation (0.51) was revealed between the potassium balance and the change in its content in the soil, determined in an extract of 0.2 n. HCl (according to Kirsanov method). It was established that liming at 1.0 H_a of slightly acidic soil increased the productivity of crop rotation by 10%, which in turn led to an increase in the removal of nitrogen, phosphorus and potassium with crop yields by 10-14%. A positive balance of phosphorus was achieved only in the variant with an organo-mineral fertilizer system when applying manure and mineral fertilizers in full dose. It should be emphasized the need to take into account the return of nutrients with straw, in case of plowing in the field. It was revealed that in the organo-mineral fertilizer system, the share of biological nitrogen entering during the plowing of the clover layer is 26-28%, and about 20-23% more N is supplied during the plowing of straw. It was noted that when calculating the nitrogen balance, it is necessary to take into account its supply not only with mineral fertilizers, but also due to biological nitrogen fixation, when incorporating straw, etc. Failure to take into account these sources can lead to serious miscalculations. The organo-mineral system provided the highest productivity of the grain-grass crop rotation - 5.16 t of grain units/ha on an unlimed background and 5.73 t of grain units/ha with liming. On a slightly acidic background, the organic and mineral fertilizer systems ensured an equal crop rotation productivity of 4.28 t of grain units/ha, while liming had a slight advantage for the mineral system.

In the central zone of the Krasnodar Territory of the Russian Federation, on the pre-Caucasian low-leached heavy-duty chernozem on the basis of the P.P. Lukyanenko National Grain Center, for more than 15 years, new, more effective methods for calculating optimal doses of nitrogen fertilizing of winter wheat, characterized by high payback, have been studied. The methodological basis of the study was the assumption that when calculating optimal doses of nitrogen fertilizers, it is necessary to take into account the initial level of effective soil fertility, the state of agrophytocenosis and the planned yield. The solution of this problem is possible only with the help of a systematic analysis of the relationship of winter wheat yield with the above factors, the construction of a regression multiple nonlinear mathematical model and mathematical modeling of various situations in the search for optimal doses of top dressing. As initial information, the data obtained in long-term multifactorial field experiments were used, which resulted in the development of 2 new methods for determining the optimal doses of nitrogen fertilizing of winter crops (first and second) that meet the above requirements. The results of 3-year field experiments to study the effectiveness and payback of nitrogen fertilizing of winter wheat, depending on the methods of their calculation, are presented. The agro-climatic conditions at the time of the research, although they were different, but in general turned out to be relatively favorable for obtaining a good harvest of winter wheat. In 2015 and 2016, comparative tests of the effectiveness and payback of 2 new methods for calculating the optimal doses of the 1^st and 2^nd nitrogen fertilizing of winter wheat were carried out. For comparison, 2 well-known, widely used in practice, “tabular” methods were selected (prototypes 1 and 2). In 2015, the study was carried out with the Grom variety (predecessor - corn for grain), in 2016 - with the Yuca variety (predecessor - winter wheat). It is shown that the use of original methods for calculating optimal doses of 1^st and 2^nd nitrogen fertilizing of winter wheat significantly increased their efficiency and payback (both 1^st and 2^nd in total) compared with the prototypes (by 35-200%), at the same time, the payback of nitrogen top dressing, the doses of which were calculated from the prototypes, was ~12- 14 kg/kg (on average for 2 years), and the payback of top dressing calculated according to the original methods was 22-24 kg/kg in 2021 (forerunner - soy, Adel and Bagrat varieties) studied the effectiveness and payback of nitrogen fertilizing when calculating their doses only by original methods. It was shown that even with a high level of yield of winter wheat in the control (~60 c/ha on average for both varieties), the use of 2 nitrogen fertilizing, the doses of which are calculated according to the original methods, allowed to achieve a yield of winter wheat of 80-90 c/ha with a payback of ~22 kg grains/kg of N fertilizers.

Anticoagulant rodenticides occupy a leading position in the practice of regulating the number of harmful rodents. The study of resistance to anticoagulants has been developed to a greater extent in relation to rodent commensals. In the conditions of field application of rodenticides in plant protection, the problem of resistance has features that are reflected in the methodology of studying this problem. The recommendations are intended to assess the resistance of the common vole (Microtus arvalis Pall), one of the most important plant pests in the Russian Federation. The results of the study will help to identify resistance and make timely changes to the regulations for the use of rodenticides or reasonably change plant protection products.

In 2 vegetation experiments laid on acidic sod-podzolic light loamy soil, a comparative study of the fertilizing value and reclamation properties of finely ground dolomite flour (DF) particles used for road construction and blast furnace slag (FS) of a metallurgical plant was carried out. It was found that 1 year after liming, DF, introduced in doses equivalent to FS in terms of neutralizing ability, contributed to a greater shift in pH_KCl and a greater accumulation of the sum of the exchange bases Ca²⁺ + Mg²⁺. In terms of the effect on the productivity of wheat straw, variations with FS, introduced in equal amounts with DF, were not inferior to the latter. The effect of liming DF on wheat grain yield was more significant than with FS. The relationship between the content of mobile Ca²⁺ + Mg²⁺ cations in reclaimed soil and the productivity of wheat grain was revealed. Empirical dependences describing the effect of increasing doses of meliorants on the transition of calcium, magnesium, zinc, iron and manganese into straw and grain of plants have been developed. It is concluded that at the first stage of the dissolution of meliorants, their chemical nature was the leading factor in achieving the effect of curing. The degree of grinding of lime materials was of secondary importance.

In the conditions of climate warming, the frequency and intensity of droughts have increased, therefore, the development of methods that increase the resistance of crops to water scarcity is of great importance. The aim of the work is to study the effect of salicylic and succinic acids on growth indicators, photosynthetic activity indicators and on the content of pigments in the leaves of plants grown under conditions of irrigation and water scarcity. Wheat plants were grown under laboratory conditions. The seeds were pre-soaked in distilled water (control), in a solution of 0.05 mM salicylic acid or in a solution of 0.05 mM succinic acid. After the appearance of the first roots on the 3rd day, the germinated seeds were transferred to 200 ml vegetative vessels filled with soil and grown at 22-24°C in natural light and daily watering. On day 5, the plants were divided into groups “watering” and “water shortage”. The “water shortage” group was stopped watering until the end of the experiment. On day 11, the indicators of the maximum and effective quantum yield of photosystem II, photochemical and non-photochemical quenching and electron flux density were determined using a FRAME-fluorimeter. On the 16th day of growing plants, the quantitative content of chlorophyll a and b and carotenoids was determined, the relative water content in shoots and roots was calculated. The relative water content in plants hardly changed when treated with acids under irrigation conditions, but in case of water deficiency, treatment with succinic acid reduced the water content in the root by 6%. In conditions of lack of moisture, acid treatment increased the effective quantum yield of photosystem II, the photochemical quenching coefficient of chlorophyll and the electron flux density by an average of 17-20%. Under irrigation conditions, treatment with salicylic and succinic acids caused a decrease in the content of chlorophyll a (by 11 and 32%, respectively), carotenoids (by 57 and 32%) and an increase in the content of chlorophyll b (by 49 and 23%). When treated with succinic acid, the total content of chlorophyll a + b decreased by 14%. In conditions of water deficiency, treatment with salicylic acid increased the relative content of chlorophylls and carotenoids by an average of 2.6 and 3.3 times, when treated with amber - by 3.5 and 2.0 times, respectively, compared with the control in terms of raw weight. The use of the studied acids can be recommended for potential use in agriculture.

The effect of retardants on tobacco plants in the seedling and field periods has been studied. It was found that two-time treatment of seedlings with the Athlete retardant in the phases “ears” and “suitable for planting seedlings” at a dose of 3.0 ml/m² and a single treatment at a dose of 3.5 ml/m² in the phase “suitable for planting seedlings” contributed to the suspension of plant growth. There was a decrease in the length of tobacco plants by 3-17, a thickening of the stem diameter by 14-19, an increase in the mass of stems by 4-11 and the mass of roots by 44-50%. The yield of standard seedlings in the versions treated with a retardant increased by 5-6%. The degree of development of the root system of plants, established by the ability to retain a nutrient mixture, increased by 61-100%. A single application of the fertilizer with the retardant properties of Cultifort Raiz at a dose of 3.0 ml/m² in the phase “suitable for planting seedlings” contributed to a reduction in the length of tobacco plants by 2-8, an increase in the diameter of the stem by 5, the mass of stems by 8, roots by 68%. The ability of the root system to retain the greenhouse mixture increased by 118%. An increase in the yield of standard seedlings by 2% was noted. During the field period, the retardant effect of the applied agrochemicals persisted for 45 days after disembarkation. The best result in obtaining an additional yield of 6.2 c/ha (by 21%) was noted against the background of the use of the Athlete drug at a dose of 3.0 ml/m² with double treatment. When using the Athlete retardant at a dose of 3.5 ml/m² with a single treatment, the additional yield was 5.4 c/ha (by 18%). The use of Cultifort Raiz fertilizer at a dose of 3.0 ml/m² (once), contributed to an increase in the yield of raw materials by 3.9 c/ha (by 13%). In the application of the standard, the highest yield increase was obtained - 9.0 с/ha (by 30%). The accumulation of dry matter (materiality) in tobacco raw materials increased with increasing doses of agrochemicals. The use of retardants contributed to the improvement of the chemical composition of tobacco raw materials, namely, an increase in the number of Schmuck (carbohydrate-protein ratio).

The long-term dynamics of the gross content and concentration of mobile forms of heavy metals (TM) in the soil of a microfield experiment laid in 1984 on sod-podzolic gleevate sandy loam soil on moraine loam (Vladimir region) is considered. Various large doses of municipal sewage sludge (MSS) and lime (dolomite flour) were introduced as meliorants. Despite the duration of the field experiment, sampling to compare the variants of the experiment on the content of TM in the soil turned out to be insufficiently systematic. Therefore, comparisons were made only on the basis of 3-4 years, and with insufficient comparability of analytical data. As a result, if in some years a significant dependence of the TM content in the soil on the doses of meliorants was obtained, then in the long-term plan, basically we can only talk about trends. From the point of view of contamination of the arable soil layer, it was found that the gross content of Cd, Zn, As was greater than the standard of approximate permissible concentration (APC) in all variants of the experiment (including control); the same is shown for Cu in all variants except control, and for Ni at maximum doses of MSS. Soil contamination in the control appears to be associated with lateral transport. Most of the total Cd and Cu content was extracted with mononormal acids. The content of mobile copper (AAB pH 4.8) (compared with acidsoluble) reacted poorly to the introduction of ameliorants.