Detailed Explanation of Soil Testing and Fertilizer Application Techniques for Celery
Celery belongs to the Apiaceae family. There are three types: water celery, dry celery (Apium graveolens), and western celery, with similar functions, though dry celery is preferred for medicinal use. Dry celery has a stronger aroma and is called "medicinal celery." However, it is not the same species as cilantro. Celery is rich in protein, carbohydrates, carotene, B vitamins, calcium, phosphorus, iron, sodium, etc. At the same time, it has the effects of calming the liver and clearing heat, dispelling wind and eliminating dampness, relieving restlessness and reducing swelling, cooling blood and stopping bleeding, detoxifying and ventilating the lungs, strengthening the stomach and promoting blood circulation, clearing the intestines and relieving constipation, moistening the lungs and stopping cough, lowering blood pressure, and calming the brain. Eating celery regularly, especially celery leaves, is very beneficial for preventing high blood pressure and arteriosclerosis, and has auxiliary therapeutic effects. The key points of soil testing and formula fertilization techniques for celery are introduced as follows:
Nutrient requirements: Celery has a high nutrient uptake during the peak vegetative growth period. During this period, the absorption of the five elements nitrogen, phosphorus, potassium, magnesium, and calcium accounts for more than 84% of the total absorption. Celery has the highest demand for nitrogen, followed by calcium and potassium, with phosphorus and magnesium being the least needed. Celery also has a large demand for boron. In boron-deficient soil or when absorption is inhibited by drought and low temperature, the leaf stalks are prone to transverse cracking, known as "stem break disease," which seriously affects yield and quality.
Fertilization: At medium fertility levels, the fertilization amount for celery throughout the entire growth period per mu is 2500-3000 kg of farmyard manure (or 350-400 kg of commercial organic fertilizer), 13-16 kg of nitrogen fertilizer, 5-6 kg of phosphate fertilizer, and 6-9 kg of potassium fertilizer. Nitrogen and potassium fertilizers are divided into base fertilizer and three top dressings, with a fertilization ratio of 2:3:3:2. Phosphate fertilizer is all applied as base fertilizer. Chemical fertilizers and farmyard manure (or commercial organic fertilizer) are mixed and applied.
Base fertilizer: Apply 2500-3000 kg of farmyard manure or 350-400 kg of commercial organic fertilizer per mu, 4-5 kg of urea, 11-13 kg of diammonium phosphate, and 4-5 kg of potassium sulfate.
Top dressing: After seedling recovery, during the heart leaf growth period, apply 6-8 kg of urea and 3-4 kg of potassium sulfate per mu; during the early stage of vigorous growth, apply 8-11 kg of urea and 3-5 kg of potassium sulfate per mu; during the mid stage of vigorous growth, apply 6-8 kg of urea and 3-4 kg of potassium sulfate per mu.
Foliar top dressing: If heart rot disease is found, spray the leaves with 0.3%-0.5% calcium nitrate or calcium chloride. Foliar spraying of boron fertilizer can avoid stem cracking to a certain extent. Spray 40-75 kg of 0.2% borax or boric acid solution per mu each time. In protected cultivation, carbon dioxide gas fertilizer can be added.