As we all know, due to the differences in production processes, raw materials, content, etc., the production costs of compound fertilizers vary significantly. When sold in the market, the price differences are particularly large. When farmers purchase them, they don't know which compound fertilizer to buy. The first difference is in the raw materials. The production of compound fertilizers uses many raw materials. Common nitrogen fertilizer raw materials include ammonium chloride, ammonium sulfate, ammonium nitrate, and urea. Among these nitrogen fertilizer raw materials, ammonium chloride is the cheapest, requiring only about 800 yuan per ton, while urea has the highest price, requiring about 2,000 yuan per ton, resulting in a cost difference of about 1,200 yuan per ton; common phosphorus fertilizer raw materials include superphosphate, monoammonium phosphate, and diammonium phosphate. Diammonium phosphate costs about 200 yuan per bag, while superphosphate costs only a few tens of yuan per bag, resulting in a cost difference of about 2,000 yuan per ton; common potassium fertilizer raw materials include potassium chloride and potassium sulfate. The cost of these two potassium fertilizers also differs by nearly 2,000 yuan per ton.

The second factor is the difference in formulations. Corn has a high demand for nitrogen and potassium. Even with the same 40% compound fertilizer, some have an oxide potassium content of only 5%, while others have a potassium content of over 10%. The same potassium fertilizer raw material, with a difference of just one content level, will result in a cost difference of around 50 yuan. If the content of a bag of compound fertilizer differs by 5 levels, the cost per ton will decrease by 250 yuan, and the cost per bag will differ by approximately 12.5 yuan. 
The third point is the difference in brands. For well-known brands, in the production process of compound fertilizers, the nutrient content is generally sufficient to maintain their brand reputation. They do not cut corners and the nutrient content is consistent with what is indicated on the packaging. However, for some small-scale workshops that produce compound fertilizers, in order to obtain higher profits, the nutrient content is often different from what is indicated on the packaging. The situation of cutting corners is more common. 
The fourth factor is the difference in production processes. There are numerous production methods for compound fertilizers. Common ones include blended fertilizers, drum granulation, high tower granulation, slow-release compound fertilizers, and controlled-release compound fertilizers. The production processes vary, and the costs also differ significantly.

Which kind of compound fertilizer is better? 
As the saying goes, you get what you pay for. If you pay a higher price, you will get a better product. A bag of compound fertilizer that costs several dozen yuan is either an ordinary blended fertilizer with simple production process or a granular fertilizer produced by a roller. Some of them are even fake ammonium chloride nitrogen fertilizers. These fertilizers have a short holding period. After corn is used, it is prone to nutrient deficiency in the later stage, making it difficult to achieve high yields. Some well-known brands of compound fertilizers have sufficient nutrient content, advanced production processes, and a long supply period after use. Corn can also achieve high yields with these fertilizers.

Which kind of compound fertilizer is better for corn? 
Corn production occurs during the hot and rainy summer and autumn seasons. The temperature is high and rainfall is frequent, which leads to easy nutrient loss and depletion. Therefore, for corn fertilization, it is recommended that you use slow-release fertilizers and controlled-release fertilizers. These two types of fertilizers have a long nutrient supply period and are less likely to be lost. As a result, corn is more likely to achieve high yields.