Spraying nitrogen fertilizer on cotton leaves from late August to early September can keep cotton leaves green, enhance photosynthesis, prevent premature senescence and increase yield. The method is to use 75-1% urea solution per mu, or to prepare a mixed solution of 1% urea and 3000-4000 times 802, and use 75 kilograms of mixed solution per mu, and spray 1 time every 5-7 days for 2-3 times.

2, spraying potassium to prevent disease

Potassium deficiency in cotton often leads to red leaf stem blight, yellow-red cotton leaves, fragile fall off, leading to premature senescence and yield reduction of cotton plants. Spraying 0.3% potassium dihydrogen phosphate solution, spraying 75 kg of the whole plant per mu for 2-3 times; Or spray with 5% plant ash soaking filtrate to prevent aging and diseases.

3, spraying zinc to prevent loops

Zinc deficiency in cotton will cause local loss of green manure in leaves, wilting young leaves and new young bolls falling off. The method of spraying zinc is: spraying 75 kilograms of zinc sulfate or zinc chloride aqueous solution with a concentration of 0. 1-0.2% per mu once every 5-7 days and continuously for 2-3 times.

4, spray boron to attack the big peach

Cotton plants are short of boron, with high node position of fruit branches, many lateral branches and thick leaves, and buds are easy to open and fall off, resulting in no flowers in buds, few flowers and fewer bolls, small peaches and low yield. Timely spraying boron and supplementing boron nutrition are beneficial to more peaches and bigger peaches. Generally, 75- 100 kg of 0.2% borax or 0. 1% boric acid solution is sprayed once every10/5 days from the flowering period, and it is sprayed continuously for 2-3 times, and it is better to add 0.5% urea when spraying.

5, spraying phosphorus to promote early maturity

From the end of August, add 1 kg calcium superphosphate into 50 kg water, soak for 24 hours (stirring frequently), filter to remove residues, and spray 100 kg used filtrate per mu, or spray 100 kg potassium dihydrogen phosphate solution with 300-500 times potassium supplement every 5-7 days, continuously.