The effect of spraying fertilizer on cotton is great in the later stage.

In the later stage of cotton growth, the nutrient absorption function of root system decreased obviously, when foliar fertilizer was sprayed to supplement nutrition, it could prevent premature senescence, disease, attack big peach, promote early maturity and strive for high quality, and the effect of increasing yield and income was remarkable.

1. Spraying nitrogen fertilizer to prevent premature senescence: in the later stage of cotton, spraying nitrogen nutrition on cotton leaves can keep cotton leaves green, enhance photosynthesis, prevent denitrification and premature senescence. Mixed spraying of nitrogen fertilizer and "regulator 802" can enhance cotton growth stamina more obviously and increase yield better. From late August to early September, the mixed solution of urea 100x and regulator 802x was sprayed once every 5-7 days, twice-3 times in succession, each time 75kg per mu.

2. Spraying potash fertilizer to control diseases: due to potassium deficiency, cotton is prone to red leaf stem blight (wilt blight) at flowering and boll setting stage, cotton leaves turn red or yellow, become thicker and wrinkled and brittle, and finally fall off, resulting in premature senescence of cotton plants and a serious reduction in yield. While preventing drought, foliar potassium spraying can reduce or inhibit the disease. Foliar spraying with 0.3% potassium dihydrogen phosphate solution, 2% potassium nitrate solution, 1% potassium chloride solution, 5% plant ash immersion (24 hours) filtrate, spray once in 7 days-10 days, 2-3 times in a row. For cotton fields that have suffered from red leaf stem blight caused by potassium deficiency, 3% potassium nitrate solution or 0.3% potassium dihydrogen phosphate mixed with 100 times urea solution can be sprayed on the leaves in time, once in 5 days and 3 times in a row, which can make the cotton leaves turn green quickly. Spray 75kg fertilizer liquid per mu each time, pay attention to wet the whole plant.

3. Spraying phosphate fertilizer to promote early maturity: spraying phosphate fertilizer in the later stage of cotton can make the seeds full, increase boll weight and open bolls early. Generally, starting from late August, 75 kg of filtrate is soaked in 2% superphosphate per mu (24 hours, often stirred), and 0.3% potassium dihydrogen phosphate solution can also be sprayed in combination with potassium supplement.

4. Spraying boron fertilizer to attack big peach: cotton is lack of boron, lateral branches are increased, fruit branches are high, leaves become thicker, buds are easy to fall off, resulting in "buds but not flowers" or "flowers but not fruit", fewer flowers and fewer bolls and low yield. Timely application of boron fertilizer can reduce the shedding of flowers and bolls, which is beneficial to more peaches and big peaches. Generally start from the bell, spray once every 15 days, spray 2-3 times, spray 0.2% borax solution 75 kg per mu each time, add 0.5% urea when spraying boron, the effect is better. First dissolve borax with a small amount of warm water, dilute it with cold water and spray it.

5. Spraying zinc fertilizer for high quality: cotton is a crop sensitive to zinc. In recent years, with the increase of nitrogen and phosphorus fertilizer application in cotton field, the proportion of a large number of elements and trace element zinc is out of balance. Available zinc in soil can not be replenished in time, which affects the growth and development of cotton and limits the improvement of cotton yield and quality. The application of zinc fertilizer is beneficial to the synthesis and growth of chlorophyll, promote the absorption of nutrients, coordinate the transport of nutrients and enhance photosynthesis in cotton. Spraying zinc fertilizer on the leaves of cotton during flowering and boll setting stage can increase the peripheral peach, prolong the life of functional leaves, increase lint percentage, increase yield and improve quality. 0.2% zinc sulfate solution is sprayed on the leaves, generally 2-3 times, each time 75 kg per mu. Foliar fertilizer should be sprayed before 9: 00 a. M. or after 5: 00 p. M. on a sunny day to prolong the wetting time of fertilizer liquid on leaves and facilitate leaf absorption. To spray fine spray evenly, pay special attention to the back of cotton leaves spray, in order to promote absorption and improve fertilizer efficiency. In order to save the working procedure and give full play to the combined effect of various nutrient elements, the above-mentioned fertilizers can be mixed according to the specific conditions, and they can also be combined with the prevention and control of diseases and insect pests and pesticides to make them "one spray with multiple effects". Foliar fertilizer should not be mixed with alkaline pesticide, plant ash should not be mixed with other taboo alkaline foliar fertilizer, phosphate fertilizer should not be mixed with zinc fertilizer.