The winter lettuce enlargement period K

During the winter lettuce elongation enlargement, must every 10 to 15 days to apply a potash and successive application of 4 to 6 times, per acre of potassium nitrate 40 to 50 kilograms, or application potassium sulfate 60 to 70 kilograms, or application of potassium dihydrogen phosphate from 25 to 30 kg, combined application of nitrogen, phosphorus and potassium compound fertilizer or soak composting of flower cake, against the clear water or slurry or retting maturity of animal manure water 50 to 60 times, pour evenly applied in the soil around the roots of lettuce plants. At the same time, every 7 to 10 days of foliar spraying a 0.1% magnesium sulfate, urea 0.2%, 0.3% potassium dihydrogen phosphate, 1000 times amino acid active liquid fertilizer mixture, or 0.5% casserole acid potassium, 1000 times humic acid active liquid fertilizer mixing liquid, continuous spray 3-5 times, uniform spray wet all leaves and stems to begin with beads of water dripping is appropriate, from the foliar potassium supplementation...