Development of the mineral fertilizer application system for cotton yards under different soil-climatic conditions of Uzbekistan

. Today, in order to develop cotton production in Uzbekistan, all attention is paid to the use of modern, promising ways of farming, in particular, to free up cotton fields for other crops and to increase the gross yield by planting cotton varieties with high fiber yield and high quality in relatively small areas, in each province and farm in the region where cotton is grown. - breeding of varieties suited to climatic conditions is being focused on. The cultivation of high and quality cotton depends primarily on the yield potential of cotton varieties and the compliance of cotton fibers with standard requirements. Therefore, creating new cotton varieties and placing the most promising ones in accordance with the different soil and climatic conditions of Uzbekistan remains an urgent task of scientists and specialists. Care of different cotton varieties, taking into account the fact that their requirements for nutrients, water, soil and climatic conditions and other agrotechnical factors are different depending on their biological characteristics, it is considered very necessary to develop specific recommendations and put them into practice.


Introduction
No matter how promising the new variety is, it is important to study its alternative agrotechnics [1]. Because not knowing the agrotechnics of the new variety has a negative effect on the growth and development of cotton. Taking into account the main factors in these agrotechnical processes, it is very important to leave cotton varieties with fertilizer and water standards, standard planting per hectare [2].
Among all agrotechnical activities, the importance of mineral and local fertilizers is important in increasing the yield of cotton [3]. Nitrogen, phosphorus and potassium from mineral fertilizers are of great importance in obtaining a high yield of cotton. The importance of nitrogen, which occupies the first place among them, for plants and all living beings is determined by its inclusion in the protein composition [4]. Protein is a component of protoplasm, that is, a living cell. It consists of several amino acids (20-25) whose structure is impossible without nitrogen. Nucleic acids are the main part of the protoplasm and the cell nucleus, in which nitrogen is in the form of nucleoproteins [5]. Nitrogen is part of chlorophyll, which participates in the process of plant photosynthesis. In addition, nitrogen is needed throughout the entire life cycle of the cotton plant [6].
If there is a lack of nitrogen element, the growth of the plant slows down, the leaves are crushed and turn light green. In this case, the stems are also thin, and fruiting slows down. When the plant is well supplied with nitrogen, the stems and leaves take on a dark green color, the formation of the pods is improved, and as a result, the productivity increases [7].
Phosphorus, in turn, is part of the substance phytin. It accumulates in seeds and serves as a reserve substance [8]. Phytin is very important during plant growth. Phosphorus is also a component of RNA and DNA substances involved in reproduction, protein synthesis, and growth and reproduction [9].
Potassium is in a mobile state in plants, and it is especially abundant in vegetative and young parts [10]. Potassium plays an important role in the growth of biocalciums. It also enhances the hydration of biocolloids and increases hydrophilic properties, which causes good water retention in the plant, low evaporation, and mild drought tolerance.

Materials and methods
The field experiment devoted to the study of the effectiveness of the application of fertilizers in different periods is being conducted in the field of the Fergana branch in the field of grassy, heavy sand, low salinity, nitrogen water level at a depth of 1. According to the analysis of the soil cross-section, the soil has a degree of salinity. According to the quantities of soil volume mass, it corresponds to the definitions in the soil cross-section ( Table 1). The amount of dry residues in the soil increased as the section deepened. According to the mechanical composition of the soil, the entire section is heavy sandy. Table 1 shows that the soil moisture content increased with the deepening of the section. When plowing the land in the experimental field, phosphorus and potash fertilizers were first applied in lumps according to the experimental scheme on October 21, 2022. On October 23, the field was plowed. Land leveling was completed on April 5, 2022. Then it was stormy, and on April 9 is was cultivated. Seed planting was carried out on April 10, during which "Uzbekistan Institute of Cotton Breeding (UICB)-2201" cotton seed was planted.
During the growing season, cotton inter-row processing, i.e. cultivation, was performed 4 times. Cotton was spun 2 times and spun 1 time. 1 treatment against agricultural pests was carried out on June 12. Cotton was fed according to the experimental scheme.
Irrigation water was applied 3 times. Cotton threading was held on June 20. Cotton harvesting was done 3 times -on September 8, 18 and 27.

Results and discussion
The amount of humus, that is, nitrogen, phosphorus and potassium in the soil. Soil samples were taken from the 0-30 and 30-50 cm layers of each variant of the soil in the experimental area in spring and autumn, and humus, total nitrogen, phosphorus and potassium were analyzed. The results of the analysis are presented in Table 2. According to the received data, the amount of humus in the 0-30 cm layer of the soil in spring was 1.94-1.97%, and it was almost the same according to the options. In the 30-50 cm layer under cultivation, their amount was equal to 1.63-1.62%.
By the autumn months, the amount of hummus has not changed much. Total nitrogen content was 0.198-0.200% in the 0-30 cm soil layer in spring, 0.197-0.200% in autumn and 0.156-0.164% in the 30-50 cm layer. The amount of phosphorus and total amount of potassium was almost the same in spring and autumn, it was around 1.490-1.510% in the cultivated layer and 1.495-1.500% in the under-cultivated layer. The soils of the experimental field are very rich in reserve nutrients and fertile soils.

Amount of reactive nitrogen, phosphorus and potassium in the soil
The amounts of nitrate nitrogen, mobile phosphorus and exchangeable potassium that plants could absorb from the soil samples were analyzed in the agrochemical laboratory. Table 3 presents the results of the analysis. In the spring, according to experimental options, the amount of nitrate in the soil in the 0-30 cm layer is 19.1-22.4 mg per 1 kg of soil, and if this soil is at an unsatisfactory level with nitrate, it is 10.3-12.6 mg in the 30-50 cm soil layer. forming, the soil is at the level of low nitrate supply. By the autumn months, their amount has increased slightly. This increase is especially noticeable in nitrogen fertilizer variants applied in large quantities at the same time.
The amount of mobile phosphorus in layers 0-30 at the average level of provision according to the options did not change until autumn. Phosphorus is insufficiently supplied in the 30-50 cm layer under cultivation. The amounts of exchangeable potassium are also moderately supplied in the cultivated and sub-cultivated soil layers. In the autumn months, their amounts did not change much.

Growth and development of cotton in the experimental field
On June 1, July 1, August 1, and September 1, plant height, crop branch, crop elements, pods, and the number of opened pods were counted. For this, 50 plants from each part of the experiment were marked and phenological observations were made every month. Data obtained during phenological observations are presented in Table 4. According to the obtained results, in the observation on June 1, there was almost no difference between the true leaf and height options. In July 1st observations, there was a significant difference in plant height, crop crown, and crop marks. In the traditional option 1, compared to other (2-3) options, the cotton was taller, the crop crown was more, and the crop mark was more.
In the 2-3 options, which were not fertilized during the flowering period of cotton, the plant was behind in terms of height, yield, and yield elements. This process continued until the end of phenological observations. In particular, in option 2, which was fertilized with nitrogen fertilizers once in the growing season, the growth of cotton was much behind compared to the conventional option 1.

Cotton seedling thickness, wilt damage and cotton weight per cocoon
In the experimental field, the thickness of cotton seedlings was determined in two periodsat the beginning of the growing season and in the fall after the operation. According to the calculation on May 30, the thickness of the cotton seedlings was 91.8-93.6 thousand per hectare. In the variety UICB-2201, when cutting the root neck of cotton stalks, it was 1.2-1.4%.
The cotton weight of one boll of this variety was 5.72-5.84 grams. Compared to option 1, the weight of cotton in the bag is significantly reduced in options 2-3. The reason is that no fertilizer was applied before flowering (Table 5).

Cotton yield
The cottons in the experimental field were picked by hand 3 times according to the prescribed procedure for all returns and options and determined by weighing. My first skin started on September 8th. More than 70% of the total harvest of cotton was harvested according to the options. The highest cotton yield was obtained from option 1. Table 7 shows cotton yield by harvest. The second harvest was on September 18, during which 7.5-8.4 tons/ha of cotton was harvested from the variants. The next third skin was held on September 27. On this day, 2.3-4.5 centners of cotton per hectare were harvested. The least cotton yield was obtained from the 2nd option, i.e. when all nitrogen fertilizers were applied during the growing season.
The highest gross yield was 43.5 t/ha, and was obtained from option 1, i.e., the traditional option with uniform distribution of fertilizers. The least cotton yield was obtained from the 2nd option, i.e., the option given in the period of application of all nitrogen fertilizers (200 kg/ha). A cotton yield of 40.3 ha was harvested from the 3rd option, where half of this fertilizer rate was applied in 2-4 leaves, and half in combing.
So, compared to the traditional 1st option, 4.3 tons less cotton was harvested from the 2nd option, and 3.2 tons less than the 3rd option. Statistical processing of cotton yield by Peregudov method was E = ± 0.39 q/ha, P = 95%, and the average yield was 41.0 q/ha (Table 6).

Conclusions
According to the data of the conducted one-year field experience, the following conclusions were drawn. The highest cotton yield of 43.5 t/ha was obtained from cotton variety UICB-2201 in option 1, where mineral fertilizers were applied to cotton in the traditional way in conditions of grassy, heavy sandy, low salinity soils of Fergana region. At least 39.2 q/ha yield was obtained in option 2, in which all phosphorus and potassium fertilizers were applied before plowing, and nitrogen fertilizer was applied during the cotton picking period, and 4.3 q/ha less cotton yield was obtained compared to option 1. Phosphorus and potash fertilizers were applied before plowing, half of nitrogen fertilizer was applied in 2-4 leaves, and half during tillering, i.e. in the 3rd option, the yield of cotton was 40.3 q/ha and 3.2 q/ha less than in the 1st option.