How to fertilize sweet potatoes

The root system of sweet potatoes is developed, and the stems and vines have the habit of rooting in the ground. They absorb fertilizer and water, and can also receive a certain yield on the steep slopes and barren land where other crops cannot grow. 

For sweet potatoes, the supply performance of nitrogen and potassium in the southern soil is poor, and attention should be paid to the application of nitrogen and potassium fertilizers, while the calcareous soil in the north has a weak supply of nitrogen and phosphorus, so nitrogen and phosphorus fertilizers should be applied reasonably.

1. Fertilization of sweet potato seedbeds:

The bed soil used in the seedbed is made of farmland fertile soil and circle fertilizer (mule and horse dung, cattle and sheep dung, etc.), crop straw, fine sand, etc. When fermenting the hot stuff, it not only releases heat, but also releases some nutrients for the potato seedlings to use. Most of the nutrients used by potato seedlings during seedling raising are provided by seed potatoes. However, after picking seedlings for 2 to 3 times, most of the quick-acting nutrients in the bed soil are absorbed by the potato seedlings. The nutrients taken away gradually increase. 

Although seed potatoes can provide nutrients, the transformation of nutrients stored in seed potatoes requires a process. The transformation of nutrients and the growth of potato seedlings can be promoted. The fertilizers used for top dressing include ammonium sulfate, chicken manure, and kang soil.

The application method is spreading or pouring with water. Usually, the fertilizer and fine sand are mixed evenly on the seedbed, and then some fertilizers scattered on the leaves of the potato seedlings are shaken off, and water is poured immediately. If ammonium sulfate is used, the dosage is 45 grams per square meter of seedbed. Top dressing should be applied 1 to 2 days after the seedlings are harvested after the wound has healed. Chicken manure and kang soil should be crushed in advance.

2. Base fertilizer for sweet potato:

Sweet potato is cultivated in ridges, and organic fertilizers are used as base fertilizers. Generally, it is concentrated on the bottom of the ridges, and then the ridges are raised to pack the fertilizer. Most of the sweet potato roots are distributed in the soil layer of 25 to 30 cm, so the deep application of organic fertilizers and phosphorus and potassium fertilizers is more important for sweet potato production. The amount of basal fertilizer varies with the cultivation area. In the northern spring potato area, it is low temperature and drought in the early stage, high temperature and rainy in the middle stage, and low temperature and drought in the later stage.

In the southern summer and autumn potato cultivation areas, the early stage is high temperature and rainy, and the later stage is low temperature and drought, so the proportion of base fertilizer should not be too high. 

The base fertilizer for high-yield sweet potatoes in Fujian, Guangdong and other provinces only accounts for 30% to 35% of the total fertilizer. According to a survey in Shandong Province, 37.5 to 52.5 tons of soil and miscellaneous fertilizers are required for spring potatoes to produce 22.5 to 30 tons of fresh potatoes per hectare. The application of phosphorus and potassium fertilizers varies with yield and soil conditions.

Generally, in a plot with a yield of 60 tons of fresh potatoes per hectare, the soil available phosphorus is above 20 mg/kg, and the quick-acting potassium is above 100 mg/kg, and phosphorus and potassium fertilizers still need to be applied. The amount of phosphate fertilizer is generally 60 to 120 kg per hectare, and the amount of potassium fertilizer is 45 to 75 kg per hectare.