1. Fertilizer requirement for whole growth cycle of lettuce: The demand for nitrogen fertilizer is higher at seedling stage, followed by phosphorous and potassium fertilizer; at mid-term, the demand for nitrogen fertilizer and potash fertilizer is increasing during the vigorous growth of lettuce. In the continuous increase, the demand of nitrogen fertilizer reaches the peak of the growth of whole lettuce, and the demand for potash is also constantly increasing. In the middle and late period, that is, the time when lettuce starts to slush, the demand for potash at this time At its peak, nitrogen fertilizer demand began to slowly decrease.
2. In addition to the growing demand for nitrogen, phosphorus and potassium, there is a great demand for other trace elements such as boron, iron, copper, magnesium, zinc and molybdenum. In the absence of copper, necrosis occurs in young leaves, which cause early fall of the leaves; in the absence of zinc, the crops appear dwarf, and the leaves are small and distorted. When they are severe, they cannot grow into seeds; in the absence of manganese, the veins lack green and affect the photosynthesis of the plants; In the absence of boron, crop roots are stunted, which seriously affects crop nutrient absorption. If lettuce lacks the necessary trace elements, it must have a greater impact on the growth, quality, and ability of lettuce to resist pests and diseases.
3. Lettuce can be divided into lettuce and loose leaf lettuce, like a cool environment, neither cold nor heat, the suitable temperature for growth is 15 ~ 20 °C, should be rich in organic matter, slightly acidic (pH 5 ~ 7) Soil cultivation. For every 1,000 kilograms of lettuce produced, 2.5 kilograms of nitrogen, 1.2 kilograms of phosphorus, and 4.5 kilograms of potassium need to be absorbed. Among them, the cabbage lettuce needs more potassium. The growth phase requires the use of nitrogen, phosphorus, and potassium fertilizers.
4. Lettuce lettuce is a herb belonging to the genus Compositae, which is suitable for organic-rich, slightly acidic clayey soil or soil that retains water and fertility. Due to the shallow distribution of lettuce roots, weak absorption capacity, and high oxygen requirements, it is desirable to have water and fertilizer, organic-rich soil and sandy loam. Lettuce has higher soil nutrient requirements. Specifically, lettuce needs more nitrogen, followed by potassium and phosphorus. It is generally considered that every 1000 kg of lettuce must absorb 3.7 kg of nitrogen (N), 1.45 kg of phosphorus (P2O5), and 3.28 kg of potassium (K2O). The lettuce grows quickly, and the nitrogen fertilizer is good. The amount of fertilizer is small at the beginning of growth, and it enters the ball stage after 70 to 80 days after sowing. The nutrient uptake increases dramatically. In the first month of the bulbous stage, the nitrogen absorption can account for More than 80% of the whole growth period, the absorption of phosphorus and potassium is similar to that of nitrogen. In particular, the absorption of potassium not only absorbs a large amount, but also continues to be harvested. Phosphorus deficiency at the seedling stage has the greatest impact on growth. Phosphorus deficiency during the shoot stage will affect the lettuce growth. K deficiency during the ball stage seriously affects leaf weight.
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