1. Fertilizer characteristics: Celery is a fast-growing vegetable with green leaves, which has strong adaptability and large cultivation area, and plays an important role in vegetable production and market supply. The absorption of nutrients by celery during growth is consistent with the increase in growth. Although the absorption of different nutrients is different, the absorption dynamics are the same, and all have an "S" shape curve, that is, as the growth amount increases, the nutrient absorption amount increases slightly. The nutrient uptake per ton of celery produced is: N2.55 kg, P2O51.36 kg, K2O3.67 kg, and its absorption ratio is 1:0.5:1.4. Practice has proved that about 2 months after the emergence of autumn celery is a key period for fertilizer and water management. In addition, celery requires more boron, boron deficiency or inhibition of boron uptake due to high temperature, low temperature, drought, etc., the petiole is prone to "cracking", stem stem disease occurs, therefore, production should be supplemented with boron fertilizer or Foliar application of multiple micro-fertilizers.
2. Fertilization technology points In the green leafy vegetables, the growth period of celery is long, so the application of base fertilizer should be emphasized. The base fertilizer should be based on organic fertilizer. It is required to apply about 75,000 kilograms of high-quality manure before the planting, and combine it with the ground to spread into the soil. A small amount of chemical fertilizer, especially phosphorus and potassium fertilizer, may also be suitably applied in the base fertilizer.
After applying the base fertilizer before planting, in order to promote the growth of celery after slow seedling, a small amount of nitrogen fertilizer should be applied during planting, with 75-105 kg of urea per hectare. In the early stage of celery, the growth is slow, and the amount of fertilizer is small. Generally, it is not necessary to apply fertilizer. Nitrogen fertilizer can be applied once at the beginning of vigorous growth, generally 150-225 kg per hectare. The topdressing method is applied in combination with irrigation. After the top dressing, the celery grew more vigorously. More than 80% of the yield of autumn celery is formed thereafter, and more than 84% of the required nutrients are also absorbed during this growth period. Therefore, 15-20 days after fertilization should be applied again, the type, quantity and method of top dressing are the same as the previous top dressing.
The period of 30-60 days after celery is the period of product organ formation, which is also the peak period of nutrient absorption. On the basis of soil topdressing, 2-3 times of foliar topdressing should also be carried out. Generally, 0.5% urea or diammonium phosphate solution can be sprayed. If the soil is insufficient in calcium and boron, 0.3% calcium chloride and 0.1% boric acid solution can be sprayed separately to improve the nutritional condition of celery, which has a certain effect on improving celery yield and obtaining high-quality commercial vegetables.
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