Summer maize generally sprouts 18 to 21 days before jointing. Entering the jointing period, in terms of external morphology, early maturing varieties, such as Ludan 50, Dandan 20, and Denghai 9, have expanded 4 to 5 leaves, showing 7 to 10 leaves; medium-maturing varieties. Single 22, Ludan 98, Nongda 108, etc., expanded 6 to 7 leaves, visible leaves 9 to 12, late maturing varieties, Denghai 11, Dandan 11 and Dandan 13 and so on, spreading leaves 8 to 9, showing leaves 10 ~ 13 pieces, this time is the best time for top-dressing and fertilizer. After corn enters the jointing stage, the stems and leaves grow vigorously, and the tassels begin to differentiate. The demand for nutrients is increasingly pressing. Applying joint-fertilizer in time can provide a good skeleton for the later high-yield production. So how much fertilizer is applied per acre? Experiments show that soil fertility is low, basal fertility is small, population is small, growth of seedlings is thin, and the yield per acre is between 250 and 300 kilograms, and the top dressing is 45% to 50% of the total topdressing fertilizer; moderately fertile plots and soil Good fertility, strong growth of seedlings, high uniformity of field population, dark green leaves, and yields of 550 to 650 kilograms of plots. To prevent seedling growth and ensure robust plant growth, jointing fertilizer can be controlled at 30% of the total fertilizer application rate. ~35% is good; the remaining fertilizer is reserved for tapping applications to meet the needs of rapid increase in trophozoites and continuous differentiation of male and female spikes. Soil fertility, base fertilizer, large populations, robust seedling growth, and high-yield plots with 650-750 kilograms of yield per mu, in order to prevent vegetative overgrowth, ensure stable growth of seedlings, maintain their plant energy conversion, and balance their metabolism. Easing the competition between groups and individuals on the living conditions, the top dressing should not be too much during this period. The jointing fertilizer generally accounts for 20% to 25% of the total fertilizer. The remaining fertilizer is reserved for attacking and attacking grain, which is conducive to the promotion of large spikes. Increase grain weight and increase production. When topdressing, deep trenches should be used to cover the soil. Do not use it on the ground. The test shows that the application of 5CM furrows is more effective than direct application on the ground. The yield increase is 10.36% to 12.37%, and the furrow application 10CM is increased by 12.58% to 16.35% compared to furrow application 5CM. Therefore, the top dressing should be better when topdressing so as to increase the fertilizer utilization rate and cultivate strong seedlings. 