The 3 types of fertilizers that sweet potatoes fear the most!

The first type of fertilizer: Chlorine-containing fertilizers (potassium chloride, ammonium chloride) - Sweet potatoes will have their yield halved if they come into contact with chlorine. 
Many villagers think that potassium fertilizer is a good thing and casually pick up a bag of potassium chloride at the agricultural supply store because it is cheap. However, sweet potatoes are a "chlorine-intolerant crop" and are extremely sensitive to chloride ions. If the fields where tobacco leaves, potatoes, and sweet potatoes are grown come into contact with chlorine-containing fertilizers, the yield and quality will drop sharply. 
How serious is the harm? Once potassium chloride or compound fertilizers containing chlorine are used, the chloride ions, like a wild beast, will immediately suppress the transfer and delivery of photosynthetic products to the tubers once they enter the soil. The leaves turn yellow and wither, lying on the ground, and the photosynthesis cannot keep up. The tubers simply cannot expand, and the yield is directly reduced. In the end, all that is produced are a bunch of small and crooked "big earthworms". Not only is it impossible to sell them for money, but even eating them at home is embarrassing. 
Correct operation: When choosing potassium fertilizer, make sure to select potassium sulfate or compound fertilizer of potassium sulfate type (check for the word "sulfur-based" on the packaging bag). You can also apply 0.2% to 0.3% potassium dihydrogen phosphate by foliar spray from June to August, once every 7 to 10 days, which will have a particularly good effect on the enlargement of tubers. Remember, when buying compound fertilizer, first check the formula table on the back. Do not bring back any that have the word "chlorine" in the formula! 
The second type of fertilizer: Uncomposted chicken manure and pig manure - "golden nuggets" turn into "poisonous substances that burn roots" 
Applying farmyard manure is a good thing, but some villagers, for the sake of convenience, directly dump the fresh manure just cleared from the pen onto the fields, claiming that it is "rich in nutrients".

How serious is the harm? Uncompletely decomposed livestock and poultry manure directly applied to the field is simply a waste of money. After being buried in the soil, it undergoes secondary fermentation under high temperature, generating a large amount of heat and toxic gases such as methane and ammonia, which "burn" the fine roots and make the sweet potato seedlings increasingly yellow and unable to survive. Even more terrifying is that raw manure is full of Escherichia coli, nematodes, and wireworms and other pathogen eggs. Once in the soil, it is equivalent to planting sweet potatoes in a disease and pest stronghold, and root rot and total crop failure are inevitable. 
The correct operation: Farmyard manure must be fully composted and decomposed. The criteria for judgment are that it turns black in color, has no foul smell and crumbles easily when pinched. If it is not crushed well at this step, no matter how many pesticides are applied later, it cannot be saved.

The third type of fertilizer: urea or high-nitrogen compound fertilizer - "Fertilizing the leaves but starving the tubers" 
In the sweet potato field, the worst situation is "over-fertilization of the plants but under-fertilization of the tubers". Some farmers rush to boost the growth of the plants, accustomed to using urea for sweet corn, and now apply it recklessly to the sweet potato field as well. Once the urea dosage exceeds the limit, the sweet potato seedlings will grow wildly during the rainy season, with the plants densely covering the ground. However, the underground tubers are left with nothing. Chloride ions will "add diesel" to the fertilizer, burning the root system. Eventually, all the nutrients are absorbed by the leaves, leaving the underground tubers without any nourishment. The nitrogen fertilizer is wasted in vain.

Correct operation: Master the "reduce nitrogen, stabilize phosphorus, increase potassium" six-character rule. During the period when the tuber mass is expanding, apply potassium sulfate in large quantities. Before each plowing, apply decomposed farmyard manure as the main base fertilizer per acre, combined with a special high-potassium compound fertilizer. In the middle and later stages, apply potassium sulfate as a top dressing. Make profits through scientific proportioning, not by brute force.