What are the classifications of compound fertilizer? How to choose?

Compound fertilizer refers to the chemical fertilizer containing two or more nutrient elements. compound fertilizer has the advantages of high nutrient content, few by-components and good physical shape. So, what are the classifications of compound fertilizer? How to choose compound fertilizer?

Classification of compound fertilizers

As there are many kinds of compound fertilizers, they can be classified from the following aspects according to the different nutrient content.

1. According to the manufacturing method, it can be divided into two categories: chemical compound fertilizer and mixed compound fertilizer. Chemical compound fertilizer refers to the fertilizer containing two or more nutrient elements made by chemical methods. Mixed compound fertilizer is a kind of fertilizer made by mechanical mixing of various elemental fertilizers. The chemical compound fertilizer is stable, but the proportion of nitrogen, phosphorus, potassium and other nutrients is fixed, so it is difficult to meet the needs of different soils and a variety of crops. The advantage of mixed compound fertilizer is that it can be prepared into various proportions of nitrogen, phosphorus and potassium according to the needs of crops and soil.

2. According to the kinds of nutrients, it can be divided into binary compound fertilizer, ternary compound fertilizer and multi-component compound fertilizer. Binary compound fertilizer refers to the compound fertilizer which contains two kinds of nutrient elements such as nitrogen, phosphorus, potassium and so on. Ternary compound fertilizer refers to the compound fertilizer containing three kinds of nutrient elements, such as nitrogen, phosphorus and potassium. Multi-component compound fertilizer refers to the compound fertilizer which contains nitrogen, phosphorus, potassium and a small amount of boron, manganese, copper, zinc and other trace elements.

3. According to the existing forms of nutrient elements, it can be divided into potassium sulfate compound fertilizer, potassium chloride compound fertilizer, ammonium nitrogen compound fertilizer, ammonium nitrate nitrogen compound fertilizer and so on. Potassium sulfate compound fertilizer, the potassium nutrient element in the compound fertilizer exists in the form of potassium sulfate, so it is necessary to mark "sulfur group" or "potassium sulfate type" on the package. Potassium chloride compound fertilizer, the potassium nutrient element in the compound fertilizer exists in the form of potassium chloride, so it is necessary to mark "chlorine group" or "potassium chloride type" on the package. The nitrogen nutrient elements in ammonium nitrogen compound fertilizers exist in the form of ammonium chloride, while those in ammonium nitrate nitrogen compound fertilizers exist in the form of ammonium nitrate.

4. According to the duration of fertilizer effect, it can be divided into common compound fertilizer, controlled release fertilizer, slow and controlled release fertilizer and so on. Controlled-release fertilizer refers to the slow release of fertilizer effect by adding controlled-release agent in the process of compound fertilizer processing. Slow and controlled release fertilizer refers to the addition of slow release agent and controlled release agent in the process of compound fertilizer processing, and the fertilizer effect can be released slowly according to the needs of crops.

5. According to the nutrient content, it can be divided into a series of high, medium and low concentration compound fertilizers. Generally, the total nutrients of low concentration compound fertilizers are between 25% and 30%, the medium concentration compound fertilizers are between 30% and 40%, and the high concentration compound fertilizers are more than 40%.

II. Selection of compound fertilizer

Compound fertilizer has obvious advantages over simple fertilizer. However, in the selection, attention should be paid to the selection according to the crop type, soil type, application period and crop harvest position, and the blind purchase and use of compound fertilizer which is not suitable for local and cultivated crops will not only affect the growth and development of crops, but also cause the waste of individual nutrient elements. and affect the yield. The correct selection of compound fertilizer in agricultural production is the key link to give full play to the effect of fertilizer and improve crop yield.

1. Look at the packing. The appearance of the package has three certificate numbers: production license, business license, registration certificate number, nitrogen, phosphorus, potassium three major nutrient elements marked, manufacturer, address and so on.

2. Look at the physical properties of compound fertilizer. The compound fertilizer with good product quality has uniform particle size, no caking and no crushing powder.

When buying, choose regular manufacturers, its production equipment and production technology are relatively advanced, the products produced are uniform particles, balanced nutrients and stable quality. The product is developed by manufacturers after long-term experiments according to the soil nutrient status and the characteristics of crop fertilizer requirements. The formula is scientific and reasonable, with strong pertinence, complete nutrients and sufficient content.

3. Choose suitable compound fertilizer according to crop or soil environment. For example, potassium sulfate compound fertilizer should be selected for taboo crops such as grape, potato, sugarcane, watermelon, eggplant and tobacco, and ammonium nitrate compound fertilizer for wheat, because the nitrogen in nitrate ammonium compound fertilizer exists in the form of nitrate nitrogen, which can be absorbed directly by wheat to improve the utilization rate of nitrogen. However, ammonium nitrate compound fertilizer can not be applied to paddy crops for a long time. Nitrate compound fertilizer is used in paddy field, which results in serious nitrogen loss due to leaching and denitrification. Long-term application in paddy field will produce some toxic nitrate and nitrite, which is bad for crop growth.

4. Choose the appropriate compound fertilizer according to the amount of fertilizer needed by crops. For example, grain crops have higher requirements for nitrogen, but slightly lower requirements for phosphorus and potassium, if phosphorus and potassium are too high, phosphorus and potassium nutrition will be wasted, but the economic input of fertilizer will be increased; root and tuber crops have lower requirements for nitrogen, but higher requirements for potassium; some cash crops have higher requirements for nitrogen, phosphorus and potassium.