Application technique of topdressing for lettuce

Lettuce was topdressing for 3 times during the whole growth period. The first topdressing was carried out 15 days after slow seedling, and 12 kg urea was applied every 667 square meters (1 mu) to promote seedling growth and sturdiness, and the second topdressing was carried out at the initial stage of heading. The third topdressing was carried out in the middle of heading, which made the leaf bulb full and enlarged. Applying 12 kg of urea every 667 square meters (1 mu) and spraying 0.3% potassium dihydrogen phosphate as foliar fertilizer is beneficial to increase production. The selection of fertilizer spraying will be carried out after 3 pm. Stem lettuce has strict requirements on fertilizer and water, and spring lettuce is sown after September of the first year, a period when it stops growing before winter. After planting slow seedlings, rapidly available nitrogen fertilizer was applied with urea 7.5 kg per 667 square meters (1 mu) to promote the increase of leaf number and the expansion of leaf area. after turning green the next year, the leaf area rapidly increased in the shape of rosette, and quick-acting nitrogen fertilizer should be applied once. 10 kg urea was applied per 667 square meters (1 mu), and topdressing combined with watering was carried out. After watering, the speed of stem hypertrophy is accelerated, and the amount of fertilizer and water required is increased. Generally, 10 kg of urea and 10 kg of potassium dihydrogen phosphate can be applied per 667 square meters (1 mu). Fertilization can also be carried out for a small number of times, because the ground is slightly dry in the period of stem hypertrophy, and foliar spraying of 1000 mg / L penicillin can inhibit bolting. For autumn lettuce, in addition to applying sufficient basic fertilizer, shallow watering and frequent watering until seedling retardation, quick-acting nitrogen fertilizer was applied after seedling retardation. 7.5 kg of urea was applied per 667 square meters, and the second fertilizer was applied during "tuanzhu". Combined with watering, 10 kg of urea or 15 kg of diammonium phosphate was applied per 667 square meters (1 mu) to accelerate leaf differentiation and leaf area expansion. When the stem began to enlarge, the third fertilizer was applied, combined with watering, urea 10 kg and 0.3% potassium dihydrogen phosphate foliar spraying every 667 square meters (1 mu). As in spring, in order to prevent bolting and increase stem weight, 500Mel 1000mg / L chloranthin or 6000ml 10000mg / L Dwarf can be sprayed.