1. Characteristics of fertilizer requirement: The demand for sweet potato nitrogen, phosphorus and potassium is the highest, followed by potassium, followed by nitrogen and phosphorus. Sweet potato has potassium, and the application of potassium fertilizer has obvious effects on yield and quality. Sweet potato seedlings absorb less nutrients, from branching and potato to strong growth of stems and leaves, the rate of absorption of nutrients is accelerated, the amount of absorption increases, and gradually decreases to the later stage. To the rapid expansion of potato tubers, the absorption of nitrogen and phosphorus decreases, while potassium The amount of absorption remains high. In the absence of nitrogen, the old leaves first appear green-deficient, the number of leaves and branches are reduced, the leaves are reduced, the internodes are shortened, and the leaves are prone to yellowing and premature aging, which seriously affects yield. Phosphorus deficiency will cause the leaves to become smaller, dark green, tarnished, and the stems will be stretched. The old leaves will have large yellow spots and become purple, and will soon fall off. In the absence of potassium, the leaves are small, the internodes and petioles become shorter, the leaves are dark green, and brown spots appear on the back of the late leaves. The sweet potato avoids chlorine, and when the application of the chlorinated fertilizer exceeds a certain amount, the starch content of the potato block is lowered, and the potato pieces are not resistant to storage.
2. Fertilization technology: The fertilization amount per mu of the sweet potato in the whole growth period is 2500-3000 kg (or commercial organic fertilizer 350-400 kg), nitrogen fertilizer 12-14 kg, phosphate fertilizer 6-8 kg, potassium fertilizer 9- 11 kg, nitrogen and potassium fertilizer base fertilizer and secondary top dressing, phosphate fertilizer all used as base fertilizer, fertilizer and farmyard manure (or commercial organic fertilizer) mixed application.
Base fertilizer: 2500-3000 kg of farmyard manure or 300-400 kg of commercial organic fertilizer per acre, 4-5 kg ​​of urea, 13-17 kg of diammonium phosphate and 5-7 kg of potassium sulfate. It is recommended to apply long-acting fertilizer.
Topdressing: Topdressing of potato tubers during the expansion period, applying 16-19 kg of urea per acre and 13-15 kg of potassium sulfate.
Top dressing: In the middle and late stages of sweet potato growth, 0.5% urea dilution, or 2%-3% calcium superphosphate solution, or 5% grass gray water, or 0.2% potassium dihydrogen phosphate solution can be sprayed on the surface. Spray once every 6-7 days and spray 2-3 times.
2. Fertilization technology: The fertilization amount per mu of the sweet potato in the whole growth period is 2500-3000 kg (or commercial organic fertilizer 350-400 kg), nitrogen fertilizer 12-14 kg, phosphate fertilizer 6-8 kg, potassium fertilizer 9- 11 kg, nitrogen and potassium fertilizer base fertilizer and secondary top dressing, phosphate fertilizer all used as base fertilizer, fertilizer and farmyard manure (or commercial organic fertilizer) mixed application.
Base fertilizer: 2500-3000 kg of farmyard manure or 300-400 kg of commercial organic fertilizer per acre, 4-5 kg ​​of urea, 13-17 kg of diammonium phosphate and 5-7 kg of potassium sulfate. It is recommended to apply long-acting fertilizer.
Topdressing: Topdressing of potato tubers during the expansion period, applying 16-19 kg of urea per acre and 13-15 kg of potassium sulfate.
Top dressing: In the middle and late stages of sweet potato growth, 0.5% urea dilution, or 2%-3% calcium superphosphate solution, or 5% grass gray water, or 0.2% potassium dihydrogen phosphate solution can be sprayed on the surface. Spray once every 6-7 days and spray 2-3 times.
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