Common fertilizer and dosage of extra-root topdressing

The pure urea is white crystal, the industrial product is white or yellowish small particles, and the nitrogen content is 44Mel 46%. It is a neutral fertilizer with low hygroscopicity and soluble in water. It is the variety with the highest nutrient content in solid nitrogen fertilizer. Because of fast foliar absorption, high utilization rate and high yield increasing effect, it is the most suitable to be used as extra-root topdressing. The concentration of spraying depends on the type and season of crops, and the range is roughly as follows: Gramineae crops, such as rice, wheat, corn and cotton. The suitable concentration is 1 Mel 2%; the suitable concentration of vegetables, such as cucumber, eggplant, watermelon and potato, etc., is 0.5-1.5%; and the spraying concentration of hotbed seedlings is 0.1-0.3%.

Calcium superphosphate is a gray-white powder, slightly sour, easy to absorb moisture, caking and corrosive. Generally contains 12-20% phosphorus, soluble in water, is an acid available phosphate fertilizer.

Preparation method of calcium superphosphate solution: first take 10 kg of calcium superphosphate and add 100 kg of water to make 10% of the mother liquor. After adding water, stir fully and rest overnight. After the insoluble matter has settled, take the supernatant and dilute it with water according to the desired concentration. The spraying concentration of Gramineae crops, such as wheat, millet, rice, etc., is 1.5-3%.

? Potassium dihydrogen phosphate white or gray crystal, containing 52% phosphorus and 34% potassium. The hygroscopicity is small, soluble in water, and the aqueous solution is acidic, which is a high concentration of available phosphorus and potassium compound fertilizer. Because of the high price, it is mainly used for extra-root topdressing at present. This kind of fertilizer spraying is mainly used for field crops, such as wheat and corn, etc., from jointing to booting stage, and the suitable concentration is 0.2-0.3%. It is sprayed every 5-7 days, and it should be sprayed 2-3 times continuously during fertilization, which has a good yield increasing effect.

Boric acid white crystal powder, generally contains 17% boron, soluble in water, hand rubbing has a smooth feeling, is a quick-acting boron fertilizer, suitable for extra-root topdressing, should be applied in the case of boron deficiency in soil and crops, do not excessive. Corn, soybeans, etc., suitable spraying concentration is 0.1-0.15%; cabbage, radish, lettuce, celery, etc., spraying concentration is 0.05-0.1%.

? Borax white crystal, containing 11% boron, soluble in water, hand rubbing has a rough feeling, which is the best difference from boric acid. It is one of the commonly used boron fertilizers and can be used as extra-root topdressing. It should be applied when it is clear that there is a lack of boron in soil and crops. Corn, soybeans, etc., the suitable concentration of spraying outside the root is 0.1-0.25%; cabbage, radish, celery, lettuce and so on, the spraying concentration is about 0.1%.

?