What fertilizer do leafy vegetables need

Leafy vegetables include two categories, the first is the young leaves and stems for food vegetables, such as chard, celery, spinach, amaranth, lettuce, etc., known as leafy greens: the second category is the leaf ball for food vegetables, such as nodular kale, cabbage (nodular cabbage), cauliflower, etc., known as nodular leafy vegetables. Although leafy vegetables more varieties, but in the nutritional needs, there are commonalities: 

(1) in the absorption of the three elements, mainly nitrogen and potassium, the ratio of the two is about 1:1, compared with fruit and vegetables, the demand for nitrogen increased significantly, if the lack of nitrogen and potassium, it is difficult to form fresh, high-quality products; in addition, cabbage, kale, spinach, etc. are more calcium and phosphorus vegetables. 

(2) leafy vegetables root system into the soil shallow, shallow-rooted crops, root drought resistance, flood resistance are low, soil drought will seriously hinder its absorption of calcium, boron, and thus more prone to calcium deficiency, boron deficiency symptoms, in the fertilization should also pay attention to the amount of fertilizer and parts, should be shallow, less layers of multiple fertilization. (3) nutrient elements in leafy vegetables accumulate throughout the reproductive period, but the peak of nutrient uptake rate in the early stages of fertility, the peak of nutrient uptake of leafy vegetables in the early stages of bulb, therefore, the early nutrient supply to leafy vegetables yield, quality is very important.