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Regarding the characteristics of compound fertilizer, it is necessary to start from secondary processing. For example, the compound fertilizers are composed of different elemental fertilizers including urea, calcium, potassium chloride and the like, which are mixed and added with a small amount of binder to granulate. Its shape is granular, nutrients include nitrogen, phosphorus, potassium, and it is possible to add one or several medium and trace elements. The form of nutrients in the compound fertilizer may be completely water-soluble, or may have a small amount of insoluble or weak acid dissolved. For example, the nitrophosphate fertilizer has weak acid solubility and water solubility. Therefore, the main characteristics of compound fertilizer can be summarized as follows: First, the shape is a particle with a certain compressive strength, can be gradually dissolved and released nutrients after being applied to the soil; Second, the nutrient composition is complex, containing nitrogen, phosphorus or Potassium may contain trace elements such as calcium, magnesium, sulfur, iron, molybdenum, etc. 3. The nutrient forms in the compound fertilizer particles are diverse, such as nitrogen, which may be in the urea-based state or in the ammonium or nitrate state. Phosphorus may be completely water soluble or partially water soluble; potassium may be thio or chloro. In short, the compound fertilizers that have been processed by secondary fertilizers have their composition and technical content increased, so the cost increases and the price increases accordingly. Therefore, the correct application of compound fertilizer on crops needs to be considered comprehensively. Only when the compound fertilizer traits are matched with the soil and crop traits, can we achieve a win-win situation of increasing production and increasing income.
Under the above principles, the specific application methods of compound fertilizer can be summarized as follows:
1. Compound fertilizer is suitable as base fertilizer. Application method of base fertilizer: The granule compound fertilizer containing various nutrients of nitrogen, phosphorus and potassium is applied to a certain depth of soil when cultivating land before sowing. The depth of fertilization varies from crop to crop, the depth of fertilization of food and vegetables is generally 20 cm, and the depth of fertilization of fruit trees is 30-40 cm. Only when the compound fertilizer is applied to a certain depth can the demand for nutrients in the middle and late crops be supplied. The compound fertilizer used as the base fertilizer applies all the phosphorus and most of the potassium required for the growth period of the crop. Nitrogen is too active, and only part of it can be applied to the base fertilizer through compound fertilizer. At least half of the nitrogen should be applied as top dressing in the form of elemental nitrogen fertilizer during the vigorous growth period of the crop. Therefore, the compound fertilizer is suitable for the base fertilizer, and the nitrogen ratio cannot be too high.
The nutrient ratio of nitrogen, phosphorus and potassium in any compound fertilizer is fixed. The calculation of the amount of base fertilizer is based on the content of phosphorus or potassium, and half of the nitrogen fertilizer needs to be applied in the middle and late stages.
2. Compound fertilizers are generally not suitable for top dressing or water flushing. Among them, the phosphate fertilizer, even if it is fully water-soluble, is rarely moved downward on the soil surface, and the crop root system is difficult to use. Although the vegetable farmers in Guangdong are accustomed to importing the general-purpose 45% (15%-15%-15%) compound fertilizer into water, the leafy vegetables have obvious fertilizer efficiency, but their nutrient utilization rate is low, not only waste of fertilizer. The cost is not cost effective and needs improvement.
The medium and low concentration of nitrogen and phosphorus binary compound fertilizer can be applied as seed fertilizer, but it should be noted that the seed is separated from the fertilizer. The organic-inorganic compound fertilizer can be used as a base fertilizer in a larger amount.
3. Compound fertilizer should be applied in combination with elemental fertilizer. For the nutrient supply of the whole growth period of the crop, on the basis of applying the compound fertilizer as the base fertilizer, half of the elemental nitrogen fertilizer or a small amount of potassium fertilizer should be used as the top dressing to adjust the proportion of nutrient elements, so that it is finally suitable for the high yield and high quality of the crop. need.
Rational application of compound fertilizer
Mastering the scientific application of compound fertilizer technology must first understand the characteristics of compound fertilizer, and at the same time understand the demand characteristics of external nutrient supply during the whole growth period of crops and the basic characteristics of soil, including the quantity of soil nutrients and the soil water retention and fertilizer retention. Ability, etc. This may make the farmers' friends feel too complicated, but the farmers who have experience in actual production are all considered in this way.
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