How to Formulate Base Fertilizer for Cotton? A Detailed Guide to Scientific Ratio Methods
The ratio of base fertilizer (nitrogen, phosphorus and potassium fertilizers) for cotton is generally 1:0.3:1. According to measurements, a yield of 100 kg of cotton per mu requires the absorption of 12 kg of nitrogen, 4 kg of phosphorus pentoxide and 12 kg of potassium oxide, and the fertilizer requirement is 5-6 times that of cereal crops. In addition, an appropriate amount of compost, waterlogged manure, night soil and urine fertilizer, etc. must be applied to promote high cotton yields.
Key points of fertilization for each growth stage of cotton:
1. Seedling fertilizer
Seedling fertilizer is the first topdressing carried out during the planting process. Proper topdressing of seedling fertilizer can effectively promote the development of the plant roots, extend and expand the roots, enhance the absorption capacity, speed up transport and improve the growth of the seedlings. When topdressing seedling fertilizer, nitrogen fertilizer is mainly used, but care must be taken not to over-apply it. The specific application amount is determined by the growth of the seedlings and the fertility of the soil. If the base fertilizer is insufficiently applied and the seedlings grow weakly, a high-nitrogen compound fertilizer can be used to promote growth. If the soil fertility is sufficient and the seedlings grow strongly, the application of seedling fertilizer can be stopped.
2. Flower bud fertilizer
After flower buds appear on the cotton plant, the demand for nutrients becomes relatively large, so nutrient supplementation must be strengthened at this time. Reasonable topdressing during the flower bud stage is conducive to the later plant growth. It can not only keep the plant growing both vegetatively and reproductively, but also speed up the growth rate of the plant so that it fruits as early as possible. Compound fertilizer can be used for flower bud fertilizer, digging a trench around the plant and using the trench application method. However, care must be taken not to let the plant come into contact with the fertilizer, especially the roots; otherwise the fertilizer will burn the roots, causing root damage and hindering nutrient absorption and transport.
3. Flower and boll fertilizer
It was mentioned earlier that when flower buds appear on cotton, the fertilizer demand gradually increases. When cotton growth enters the flower and boll stage, this is the period of greatest fertilizer demand during the planting process. Therefore, at this time, sufficient nutrients must be ensured for plant growth, and compound fertilizer can also be used instead. The topdressing time is determined by the growth situation. If the soil fertility is relatively low and the cotton growth weakens, fertilization can be appropriately advanced. It is mainly applied after the plant flowers. When the flowering rate of the plant reaches 4/5, select 1-2 plants with strong growth and begin topdressing.
4. Topping fertilizer
The main purpose of topdressing topping fertilizer is to prevent premature senescence caused by a lack of nutrients during the later fruiting and maturity stage of cotton. Topping fertilizer can enhance the resistance of the plant, maintain the growth rate of the plant, reduce the incidence of pests and diseases, and also help increase yield and improve quality. The method and time of fertilization are mainly to topdress outside the roots of the plant after topping, and different fertilizers are used according to the plant's nutrient deficiency. For example, urea should be applied when nitrogen is deficient, and potassium dihydrogen phosphate should be applied when phosphorus is deficient. This can effectively prevent yellowing and leaf drop and premature senescence in the later stage of the plant.
The above is the relevant introduction to the base fertilizer ratio for cotton. I hope it is helpful to everyone.