The transition to a market-oriented economy requires a fundamental revision of cotton cultivation technologies. Under the current conditions of Tajikistan, taking into account the fertility characteristics of soils and the agroecological conditions of the country's regions, the efficient use of mineral and organic fertilizers, adherence to scientifically based application rates, timing and methods of micronutrient application, timely implementation of agronomic practices, and proper irrigation management are the key factors for obtaining high and stable yields under changing climatic conditions. These requirements should be scientifically substantiated and introduced into the practices of farms engaged in cotton production. The implementation of these recommendations will contribute to increased productivity, improved fiber quality, a reliable supply of raw materials for the textile industry, and strengthened national food security.
Before fertilizer application, it is recommended to conduct an agrochemical soil analysis to determine the actual nutrient content and prevent excessive fertilizer application.
Depending on the soil and climatic conditions of different regions of the country, the following annual nutrient application rates are recommended. Cotton is a crop with a high demand for nutrients and a long nutrient uptake period. Therefore, determining the correct annual fertilizer rate is of primary importance.
According to scientific research, the production of 1 centner (100 kg) of seed cotton requires, on average:
Nitrogen (N): 5.0–6.0 kg;
Phosphorus (P₂O₅): 3.0–4.0 kg;
Potassium (K₂O): 6.0–8.0 kg.
To obtain a high-quality cotton yield of 30–35 centners/ha (3.0–3.5 t/ha), the following fertilizer rates are recommended.
Nitrogen (N): 150–250 kg/ha (active ingredient);
Phosphorus (P₂O₅): 120–140 kg/ha;
Potassium (K₂O): 60 kg/ha.
Nitrogen (N): 220–250 kg/ha;
Phosphorus (P₂O₅): 140–150 kg/ha;
Potassium (K₂O): 60–80 kg/ha.
Nitrogen fertilizers: Ammonium nitrate or urea;
Phosphorus fertilizers: Single or double superphosphate;
Potassium fertilizers: Potassium sulfate (especially on saline soils, since potassium chloride may adversely affect fiber quality).
Fertilizers should be applied according to the following schedule.
Before primary tillage, it is recommended to apply:
the entire annual rate of organic manure (15–20 t/ha);
60% of the annual phosphorus fertilizer rate (P₂O₅), or up to 90% if the annual phosphorus rate exceeds 60 kg/ha;
the entire annual potassium fertilizer rate (K₂O).
If the potassium rate is less than 60 kg/ha, it is preferable to apply it at planting and during the second and third top dressings (before flowering).
On light-textured and stony soils, as well as during rainy spring conditions on long-irrigated lands, 30–45 kg/ha of nitrogen should be applied during pre-planting soil preparation.
To promote rapid establishment and early growth of seedlings with an underdeveloped root system, apply simultaneously with sowing:
Nitrogen: 10–15 kg/ha;
Phosphorus: 15–20 kg/ha.
The fertilizer should be placed 4–5 cm away from the seed and at a depth of 7–8 cm.
On medium-textured soils, three top dressings are recommended, while on light sandy soils up to four applications may be required.
First application: At the 2–3 true-leaf stage.
Second application: At the beginning of the squaring (flower bud formation) stage.
Third application: At the beginning of flowering.
Nitrogen and phosphorus fertilizers are applied during the first and second top dressings, while nitrogen, phosphorus, and potassium are applied during the third. The largest nitrogen dose (up to 70 kg/ha) should be applied during the second top dressing.
Where reduced nitrogen rates are used (after alfalfa or green manure crops), nitrogen should be applied only during the first and second top dressings following alfalfa, and during the second and third top dressings following green manure crops.
First top dressing: 10–12 cm from the plant row at a depth of 8–10 cm;
Second top dressing: 15–20 cm from the row at the same depth;
Third top dressing: In the inter-row furrows at a depth of 5–6 cm.
The final top dressing should be completed no later than July 10, or July 20 on stony soils.
During the squaring and flowering stages, foliar application of fertilizers containing boron (B) and zinc (Zn) is recommended. These micronutrients help reduce flower bud shedding and improve cotton fiber quality.
On farms equipped with drip irrigation systems, the application of fully water-soluble fertilizers through irrigation water (fertigation) can increase nutrient use efficiency by 30–40%.
Excessive application of nitrogen fertilizers may cause secondary soil salinization and nitrate contamination of groundwater. Therefore, scientifically established fertilizer application rates should be strictly observed.
The recommended fertilization technology should be energy-efficient, cost-effective, and economically viable while ensuring high cotton yields and compensating production costs through increased productivity.
