What are the effective methods for increasing cotton yield and disease resistance?
How can cotton be made to increase yield and resist disease? What are the tricks? Surveys conducted in some cotton-growing areas found that only about 45% of cotton growers apply nitrogen, phosphorus and potassium compound fertilizer; most farmers apply ammonium bicarbonate, urea and superphosphate, and about 15% of them use only phosphate fertilizer as a base dressing. This situation shows that in...
How can cotton be made to increase yield and resist disease? What are the tricks?
Surveys conducted in some cotton-growing areas found that only about 45% of cotton growers apply nitrogen, phosphorus and potassium compound fertilizer; most farmers apply ammonium bicarbonate, urea and superphosphate, and about 15% of them use only phosphate fertilizer as a base dressing. This situation shows that many cotton farmers in cotton-growing areas have not paid attention to potassium application, which is not conducive to high-yield, high-quality and abundant cotton production.
According to data, producing every 50 kg of lint cotton requires absorbing 9 kg of pure nitrogen, 3 kg of pure phosphorus and 8 kg of pure potassium from the soil; to produce 100 kg of lint cotton, 13 kg of pure nitrogen, 4.5 kg of pure phosphorus and 13 kg of pure potassium are needed. It can be seen that the ratio of the three is 1:0.35:1, which also shows that cotton is a potassium-loving crop. Cotton production practices in recent years show that no matter which type of insect-resistant hybrid cotton variety is used, the demand for potassium fertilizer is relatively large, especially under continuous cropping, where attention should especially be paid to supplementing potassium fertilizer. Applying potassium to cotton can enhance physiological activity, improve the utilization rate of nitrogen fertilizer, promote the growth of cotton roots, stems, leaves and reproductive organs, prolong the functional period of leaves, and prevent premature senescence. Especially in cotton areas with severe Fusarium wilt, applying potassium can enhance disease resistance and stress resistance and reduce its harm. Because potassium is very active in the cotton plant body and can undergo replacement and substitution with other elements, it helps increase the concentration of cell sap and the permeability of membranes, thereby promoting the plant's absorption and synthesis of nitrogen and phosphorus, improving cotton's cold tolerance and economic water use capacity, and providing a very good protective effect for early-sown cotton and cotton planting in arid areas. In production, because people emphasize nitrogen and neglect potassium, cotton field soil cannot receive supplemental potassium nutrition; coupled with predatory management of the soil year after year, potassium resources in cotton soil decrease year by year, blocking the transport and conduction of nutrients in the cotton plant body, leading to a decline in yield year by year, which has become an obstacle factor restricting high cotton yield.
When cotton lacks potassium, the first sign is yellow-white patches on the leaves; afterward the leaves gradually turn light green, and yellow spots appear between the veins, with the central parts of these spots dying first. At the same time, many brown stained spots appear at the leaf tips and edges, and after rotting they curl downward, finally the whole leaf turns brown and then dries up and falls early. Potassium-deficient cotton plants also have significantly shorter lateral roots and fewer roots, short and thin stems, aggravated shedding of squares and bolls, fewer and smaller bolls, and difficulty maturing and opening, with fiber quality declining. In severely potassium-deficient cotton plants, excessive and early leaf drop causes the plant to die prematurely, the so-called red-leaf stem blight; even if some large bolls have formed, in the later stage a large number of large bolls will also shed, causing severe yield reduction.
Potassium deficiency in cotton is relatively common, but generally it only becomes fairly obvious in the later stage, and by then it is too late to supplement potassium fertilizer, so emphasis should be placed on adding organic fertilizer to cotton fields that have historically been deficient in potassium. In addition, according to the nitrogen and phosphorus application situation in the cotton field, a certain amount of potassium fertilizer should also be applied in combination; the potassium application rate per mu of cotton field should be no less than 15 kg, and potassium-deficient cotton fields can be increased to 20-25 kg. The input ratio of nitrogen, phosphorus and potassium should be 1:0.3:0.8-0.9, which is relatively suitable. The specific application is: at sowing or transplanting, on the basis of applying 2500-4000 kg of high-quality farmyard manure per mu, mix in 10-15 kg of potassium chloride or potassium sulfate, or 40-50 kg of plant ash, or 2-3 kg of potassium dihydrogen phosphate as a base dressing, which can meet the cotton's potassium needs throughout the entire growth stage. For cotton fields with insufficient potassium fertilizer in the early stage, 10-15 kg of potassium chloride can be buried and applied at the bud stage, and 5-7.5 kg of potassium chloride per mu can be buried and applied at the flowering and boll stage. In the middle and late stages, because root absorption capacity weakens, 0.2% potassium dihydrogen phosphate can be sprayed on the leaves 2-3 times. Spray 50-60 kg of fertilizer solution per mu each time. This can not only enhance the cotton's staying power and prevent premature senescence, but also help form more bolls and larger bolls; it is an important measure for improving cotton yield and quality.
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