Full process fertilization plan for cotton

To complete the normal growth and development process of cotton, it is necessary to absorb 16 elements from the environment, including carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, copper, iron, manganese, zinc, boron, molybdenum, and chlorine. The minimum nutrient rate refers to the fact that the yield of cotton is mainly determined by the most deficient element among the 16 elements, and each element is equally important and irreplaceable. Cotton requires different types and amounts of nutrients during different growth and development stages, so it is necessary to scientifically fertilize according to the fertilizer requirements of cotton to promote high yield.

1. Fertilization requirements of cotton

(1) The role of nitrogen, phosphorus, and potassium in cotton growth and development

The effect of nitrogen on cotton is most significant and lasts the longest. From the seedling stage to the flowering and boll setting stage, an appropriate amount of nitrogen supply is required. Appropriate nitrogen supply, dark green cotton leaves, robust plants, multiple buds and bolls, high yield, and good quality. If there is too much nitrogen supply in the early stage, it will cause cotton to grow excessively. If there is insufficient supply in the middle stage of growth, the cotton leaves will turn yellow and small, shed more, and age early in the later stage, resulting in low yield; If there is excessive supply in the middle and later stages, it will cause cotton to grow excessively, reduce production in the later stages, and lower quality. Phosphorus can promote root development in the early stages of growth, promote early emergence of strong seedlings, and play an important role in early emergence of buds and early flowering; In the later stage of growth, it can promote cotton ripening and increase boll weight. Potassium can play a role in strengthening branches and increasing resistance to adverse factors; When potassium deficiency occurs, plants are susceptible to diseases, their leaves turn red, and they wither prematurely. The red leaf stem blight of cotton is mainly caused by potassium deficiency.

(2) The Fertilization Characteristics of Cotton

From the above table, it can be seen that the overall trend of fertilizer demand for cotton throughout its growth period follows a dynamic pattern of "less more less". During the seedling stage, there is less absorption, but after budding, the absorption significantly increases. It reaches its peak at the flowering and boll stage, and enters the shedding stage to decline. The absorption capacity of the root system weakens, resulting in a rapid decrease in absorption. The absorption characteristics of nitrogen, phosphorus, and potassium in cotton at different growth stages are also different. The peak of nitrogen fertilizer absorption occurs before (from the initial flowering period to the peak flowering period), while the peak of phosphorus and potassium fertilizer absorption occurs after (from the peak flowering period to the boll opening period). This is beneficial for the application of phosphorus and potassium nutrients to multiple bolls and promote early maturity.

(3) Fertilization principles for cotton

For every 50 kilograms of lint produced, cotton absorbs approximately 13.35 kilograms of nitrogen, 4.65 kilograms of phosphorus, and 13.35 kilograms of potassium from the soil. The ratio of nitrogen, phosphorus, and potassium is 1:0.3:1. But as the yield increases, there is a decreasing trend in fertilizer demand. Therefore, the increase in cotton yield is not solely dependent on fertilizer factors, but rather the result of the comprehensive effect of various cultivation techniques and measures. The fertilization principle for cotton should be based on base fertilizer as the main method and supplemented by topdressing; Organic fertilizers are the main component, with chemical fertilizers as a supplement. Traditional fertilization techniques are based on the application of sufficient base fertilizer, and according to the fertilizer requirements of cotton at different growth stages, the principles of "light application of seedling fertilizer, stable application of bud fertilizer, heavy application of flower and boll fertilizer, and supplementary application of top cover fertilizer" are mastered. Simplified fertilization techniques eliminate seedling fertilizer, bud fertilizer, and top cover fertilizer, and the fertilization measures are "sufficient application of base fertilizer, heavy application of flower and boll fertilizer".

2. High yield fertilization technology for cotton

(1) Apply sufficient base fertilizer

Apply compound fertilizer, organic fertilizer, and trace element fertilizer as base fertilizer. It is best to choose balanced or high nitrogen and potassium nutrient rich fertilizers for compound fertilizers, such as San'an 18-18-18, 20-5-20 and other nutrient allocation ratios (three numbers respectively represent the percentage of nitrogen, phosphorus, and potassium content). Compound fertilizers with nutrient content above 50% should be used at a rate of 40-50kg per mu, compound fertilizers with nutrient content between 40% and 50% should be used at a rate of 50-60kg per mu, and compound fertilizers with nutrient content below 40% should be used at a rate of 60-75kg per mu; Organic fertilizers should be selected with high organic matter content, thorough fermentation, and a large amount of beneficial bacteria, such as pure plant-based soybean 60 and 70 organic fertilizers, with a dosage of 400-500kg per mu; Additionally, 1-2 kg/acre of zinc sulfate and boron fertilizer (borax) should be applied. Compound fertilizer, organic fertilizer, zinc, and boron fertilizer are evenly spread on the ground, followed by tillage or deep rotary tillage, and then sowing.

(2) Staged fertilization

On the basis of applying sufficient base fertilizer and according to the law of cotton fertilizer demand, the principle of cotton top dressing is to apply seedling fertilizer lightly, steadily apply bud fertilizer, attach importance to flower and boll fertilizer, and apply top cover fertilizer.

① Light application of seedling fertilizer

After the emergence of cotton seedlings, the nutrients stored in the seeds themselves are basically consumed. In addition, the soil temperature is low at this time, the nutrient decomposition is slow, and the lateral root absorption ability is poor. Therefore, applying a certain amount of chemical fertilizer has certain benefits in promoting strong seedlings. During the seedling stage, nitrogen fertilizer is generally used as the main fertilizer, and can also be mixed with phosphorus fertilizer and decomposed cake fertilizer for topdressing. For example: 30-5-5 high nitrogen fertilizer, 10-15 kg/mu. The top dressing method adopts deep trench application and soil covering, and small water irrigation is used once in areas with conditions. Suitable late application should be applied to cotton fields with fertile soil and vigorous growth; Cotton fields with poor soil fertility and weak growth should be applied appropriately early. If boron fertilizer is not applied to the base fertilizer, borax solution can be sprayed every 7-10 days after cotton flowering, with a concentration of 0.1%~0.3%. Continuous spraying for 3 times generally has a good yield increase effect.

② Stable application of bud fertilizer

After the emergence of cotton buds, the demand for nutrients begins to increase. The nitrogen absorption during the bud stage accounts for about 11% to 20% of the entire growth period. The bud stage is mainly focused on rooting, which is also a key period for shaping high-yield plant types During this period, the number of leaves increases and the nutrient absorption surface gradually expands, which is a period of simultaneous growth of nutrients and reproduction. However, nutrient growth still dominates, and the growth of cotton plants accelerates and the individual size increases, significantly increasing the demand for nitrogen, phosphorus, and potassium. At this stage, the accumulation rate of phosphorus and potassium accelerates, and the accumulation rate is higher than that of nitrogen. During the bud stage, a certain amount of fertilizer should be applied to meet the needs of cotton plants for growth, but excessive fertilizer should be prevented from causing excessive growth. Therefore, stable and skillful application should be mastered. According to experiments, applying less bud fertilizer to strong seedlings increases yield by 6.4% compared to applying more bud fertilizer; Applying more bud fertilizer to weak seedlings increases yield by 8.4% compared to applying less fertilizer; Applying bud fertilizer to vigorous seedlings reduces yield by 10% compared to not applying it; The yield reduction of vigorous seedling application is 16% compared to no application, which indicates that the key to applying bud fertilizer is to apply it reasonably according to the growth of the seedlings. Generally, a certain amount of medium phosphorus and high potassium fertilizer can be applied in the early stage of cotton budding. For example, apply a large amount of water-soluble fertilizer 9-15-30+TE (trace elements), 4-6 kilograms per mu, mixed with water 500-1500 times, and apply every 10-15 days.

③ Re apply flower and bell fertilizer

The flowering and boll period is the period when cotton needs the most nutrients, and heavy application of flowering and boll fertilizer has a significant effect on achieving multiple "three peaches". The amount of topdressing should account for half or more of the total amount of topdressing during the entire growth period. But the specific operation should be tailored to local conditions, and cotton fields with abundant bud fertilizer, fertile soil, and vigorous growth should be applied appropriately late; Cotton fields with poor soil fertility, low basal fertilizer, and weak growth should be applied appropriately early. During this period, it is better to apply high nitrogen and potassium fertilizers during the early flowering period. For example, 20-5-20 high nitrogen and potassium, 20-25 kg/mu, combined with potassium dihydrogen phosphate, has a better effect.

④ Supplementary application of top cover fertilizer

The main purpose of applying top fertilizer is to prevent early senescence of cotton due to fertilizer deficiency in the later stage, and to strive for more autumn peaches and an increase in boll weight. At this time, root topdressing is generally not used for supplementary fertilizer application, and external topdressing is often used. This method has fast fertilizer efficiency and good results. For cotton fields that are deficient in nitrogen, phosphorus, and potassium, or have excessive growth and late maturity, balanced water-soluble fertilizer 20-20-20+TE (trace elements) can be sprayed, 4-6 kg/mu; Especially for anti insect cotton fields, it is advisable to spray early and frequently. For cotton fields with severe lace and boll shedding, 0.2% borax solution of 50-70kg can be sprayed per acre to achieve high cotton yield.

3. Key management techniques

(1) Seedling management: ① Characteristics of seedling growth: It is a nutritional growth stage centered on the growth of roots, stems, and leaves. ② Seedling management goals: to have early, complete, uniform, and strong seedlings, and cultivate strong root systems Seedling stage field management measures: early release of seedlings and soil sealing to prevent temperature reduction and soil moisture loss; Early and middle tillage and weeding can increase soil temperature and promote root growth; Early replanting to ensure the number of retained seedlings; Early seedling setting (end of one leaf); Early prevention and control of diseases and pests.

(2) Bud stage management: ① Fertility characteristics: Nutritional growth and reproductive growth go hand in hand, with nutritional growth being the main focus; ② Management objective: to have more buds, bloom early, grow steadily, and set up a high-yield framework Cultivate and loosen soil during the Leiqi field management measures; Chemical regulation+water and fertilizer operation research; Prevention and control of diseases and pests; Promote weakness and control prosperity; Peel off the mask before head watering, etc.

(3) Flower and Boll Period Management: ① Growth Characteristics: Nutrient growth and reproductive growth are flourishing in the early flowering period, but nutrient growth weakens and reproductive growth strengthens after flowering. It is a critical period for yield formation and requires the most fertilizer and water Management objective: Early harvest of pre harvest peaches and multiple harvest of post harvest peaches, increasing boll weight, and preventing premature aging Flower and Boll Period Field Management: In addition to fertilization, irrigation, chemical regulation, pruning and topping, and pest control for different types of cotton fields, the following two points are emphasized: first, control the sealing period and degree: The sealing period and degree of cotton are important indicators to measure whether the population structure is reasonable. Requirement: Small banks (narrow banks) will be closed in early July, and large banks will be closed from late July to early August. Sealing degree: "Not sealed near or far, not sealed below or above, with a gap in the middle.". Ensure normal growth of basal leaves and roots. If the closure is too late, it indicates that the population is too small, the growth is insufficient, and the light and soil resources cannot be fully utilized; If the row is closed too early, it indicates that the population is growing too vigorously, there are too many leaf layers, poor ventilation and light transmission, shading in the middle and lower parts, and severe shedding of buds and bells in the middle and lower parts. Secondly, control the plant type well: as the population density increases, the height of individual plants should be reduced, and the number of fruit branches and leaves should be reduced to facilitate ventilation and light transmission, reduce bud and bell shedding, and increase the number of complete bolls. Under suitable dense planting conditions, the ideal plant type for mulched cotton is short and robust, with thick stems and short nodes, moderate leaf volume, and short and upright fruit branches. High yield plastic film covered cotton fields generally have a plant height of 60-65cm before topping, 8-10 fruit branches, 13-14 main stem leaves, 20-25 fruit nodes, and an average internode height of 4-5cm.

(4) Management during the opening period: ① Fertility characteristics: Nutritional growth weakens and tends to stop, and cotton bolls gradually open from bottom to top. ② Management objective: To promote early maturity, prevent premature aging and excessive green and late maturity, and to open catkins from late August to early September, with green leaves supporting white catkins Field management measures: pruning; Push and ridge the plants; Artificial ripening; Harvest flowers; Residual film recovery.