The application of basal fertilizer provides a good basis for improving soil fertility and the requirements for nutrients during the entire growth and development period of the cotton plant. However, in order to obtain high cotton yield, it is necessary to top-dress fertilizer in appropriate amounts in order to ensure that the cotton has good nutrient conditions. The general principle of cotton dressing is to lightly apply Miaofei, steadily apply bud fertilizer, reapply flower bell fertilizer, and apply top-cover fertilizer. Due to the ground, due to time, due to seedlings.
(1) Lightly Miao Fei
Although the vegetative period of cotton seedlings is small, the amount of fertilizer needed is not much, but the cotton seedlings in this period are very sensitive to the supply of nitrogen and phosphorus. When the amount of basal fertilizer is insufficient, especially in low-yielding cotton fields, the application of seedling fertilizer should be emphasized to promote the development of root system and early growth of strong seedlings. In the two mature cotton fields, due to the influence of sucking fertilizer on other crops during the symbiosis between cotton and other crops, the growth of the cotton seedlings is relatively weak, and fertilizers need to be topdressed to promote growth. After the other crops are harvested, topdressing and watering should be promptly performed. Miao Fei mainly fertilizer, generally 667 m 2 application of standard nitrogen fertilizer available 3 ~ 5 kg, superphosphate 20 ~ 25 kg, potassium sulfate 5 ~ 7.5 kg, or with the development of good cake fat and human feces. High-yield cotton fields with sufficient basal fertilizer may not be used as seedlings.
(2) Stable application of fertilizer
After the emergence of cotton, it enters the period of vegetative growth and reproductive growth, and it is still dominated by vegetative growth. Fertilizer application in cotton buds needs to meet the needs of cotton development and high-yield shelf, and it must prevent improper fertilization, resulting in leggy cotton plants. Therefore, it must be applied stably and skillfully. The combination of quick-acting fertilizers and slow-acting fertilizers, chemical fertilizers and organic fertilizers are combined, and nitrogen fertilizers are compatible with phosphorus and potash fertilizers. For the cotton with good soil strength, sufficient base fertilizer and strong growth, less or no nitrogen fertilizer can be applied, but phosphorus and potash can be applied. Poor fertility, insufficient base fertilizer, and weak cotton seedlings may be applied as quickly as available nitrogen fertilizers. Normally, 10 to 15 kg of standard nitrogen fertilizer is chased every 667 m2. In general, early-onset insect-resistant cotton fields or unfertilized seedlings with poor growth potential should be properly planted and applied early. For late-onset or seedling-fertilized cotton plants, they should be applied late, with little or no application.
The application of potash fertilizer was better in the half of the base fertilizer and the bud fertilizer, and the monobasic basal fertilizer or bud and half of the flowering period also had good results, and the budding period had the worst effect. For every 667m2, topdressing potassium sulfate is 5 to 10kg. The amount of potassium fertilizer to be applied depends on the available potassium status of the cotton field soil.
Summer short-season cotton and wheat short-season cotton (Lu Mianyan No. 19, No. 30 Zhongmian, etc.) have been shortened by more than 20 days compared with spring sowing cotton. Because of its short growth period, rapid growth of seedling stage, in order to promote seedlings early hair, topdressing nitrogen fertilizer, to grasp the principle of light before the weight, the amount of early nitrogen fertilizer accounted for 60% to 70% of the amount of fertilizer. Miao fertilizer to be re-applied, generally in mid-June every 667 meters 2 urea 12 ~ 15 kg, conditions per 667 m 2 can be applied with farmyard fertilizer 3 to 5 tons. In fertile cotton fields, the amount of fertilizer applied in the early stages can be reduced.
(3) Pay attention to flower bell fertilizer
After flowering, cotton enters a period of vigorous growth and enters a period of reproductive growth. During this period, the stems, branches and leaves of cotton plants have grown to the maximum. At the same time, a large number of flowering and ringing have begun. The accumulation of dry matter has accelerated and the absorption of nutrients has increased dramatically. This is a crucial period for determining yield and quality. This period is the period during which cotton needs the most nutrients, so it is important to pay attention to flower bell fertilizer. The amount and timing of application will depend on the weather, soil fertility and growth of the cotton. This period is mainly nitrogen fertilizer, the amount of which should be about 55% of the total nitrogen application rate, 15 to 20 kg of standard nitrogen fertilizer applied per 667 m2, and high-yield fields could be increased to 30 kg. For the good fertilizer and water conditions, Shiji fertilizer and bud fertilizer are more, and the cotton field with strong growth potential should be applied when the bottom of the cotton plant stands between 1 and 2 bells. For poor soil fertility, insufficient use of basal fertilizer, less application of bud fertilizer, and weaker cotton planting fields, it is appropriate to apply early to the early flowering stage. The last flower and bell fertilizer must not be later than the end of July, so as not to apply fertilizer too late, leggy branches and leaves, greedy late maturity, affect early production increase. Hua bell fertilizer to open ditch or deep acupuncture points, so that fertilization does not see fertilizer, in order to facilitate the absorption and utilization of roots, the prohibition of soil surface application.
The boron and zinc fertilizers were sprayed on the leaves, and the flower and bell fertilizer could continuously spray 0.2% borax or zinc sulfate solution twice. Borax and zinc sulphate can also be mixed and sprayed at intervals of 7 to 10 days and sprayed on the foliage to be full of fog. The amount of fertilizer sprayed per 667 m 2 is approximately 40-50 liters in the early flowering period and 50-60 liters in the full flowering period. The spraying time is preferably after 4 pm or during cloudy days. If it rains after spraying, it should be refilled.
(4) Apply top dressing fertilizer
The main role of roof covering fertilizer is to prevent the premature decay of cotton plants, make full use of the effective growing season, compete for early autumn peaches, and increase the boll weight and lint count. The time and quantity of top-coating fertilizer application must be determined based on the growth of cotton bolls on the basis of the application of flower bell fertilizer. The application time of top dressing fertilizer is usually carried out at the end of July and early August. Generally, 667 m2 of standard nitrogen fertilizer is applied to 5 to 7.5 kg. The use of flower and bell fertilizers is late, and the number is sufficient. Cotton fields that grow too busy during the flowering period may not be applied to prevent late-maturing lust.
(5) foliar spray fertilizer
Also known as top dressing. At the later stage of growth and development of cotton plants, root activity declines and absorption capacity generally declines after mid-August. For cotton fields that need to be applied without applying top dressing, fertilizers can be dissolved in water and sprayed onto cotton leaves at a certain concentration. To make up for the lack of root absorption nutrients. The type and suitable concentration of foliar spray fertilizer are generally 1%-2% of urea, 2%-3% of superphosphate and 0.3%-0.5% of potassium dihydrogen phosphate. Spraying time is generally from mid-August to late-September. According to the growth of the cotton plant, spraying at intervals of 7 days or so, and spraying 2 to 3 times, each spraying solution of 50 to 75 kg per 667 m, sprayed on the back of the middle and upper leaves in sunny afternoon as well.
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