How to use NPK fertilizer:
1. It should be classified and applied, that is to say, the compound fertilizer varieties should be selected according to the soil and crops: rice, corn, sorghum and other cereal crops require more nitrogen fertilizers, and nitrogen and phosphorus compound fertilizers can be used; legume crops can fix free nitrogen in the air. Phosphorus and potassium compound fertilizers are selected; for economic crops, ternary or multi-component compound fertilizers suitable for local soil and climatic conditions can be used.
2. It should be applied in proportion, that is, in combination with elemental fertilizer. The nutrient composition of compound fertilizers is fixed, and only in combination with various elemental fertilizers can the needs of crops be met in different periods. Generally speaking, the compound is suitable for base fertilizer, and the general dosage is 30 ～ 40㎏. And critical period.
3. Scientific application is mainly due to proper application method. Different compound fertilizers have different ratios and forms of various nutrients, plus different soil types and crop types, so the method of fertilization should also be treated differently.
Cohesive soils have strong fertility retention and should be applied deep; sandy soils are easy to remove fertilizers and can be applied in small quantities; compound fertilizers containing ammonium nitrogen should be applied deeply to reduce losses; compound fertilizers containing phosphorus and potassium should be concentrated Application, applied near the root system, not only to prevent nutrients from being fixed, but also to facilitate crop absorption and utilization; potassium dihydrogen phosphate, which is relatively expensive, should generally not be used as a base fertilizer, but suitable as a forced fertilizer outside the roots.
When compound fertilizers are used as seed fertilizers, care should be taken to avoid direct contact between seeds and fertilizers or mixed use of seed fertilizers. Because the nutrient content of compound fertilizers is generally high, direct contact with seeds or seedling roots will affect seedling emergence, and even cause burnt seedlings and rotten. Roots, therefore, when sowing, the seeds should be separated from the compound fertilizer of hole application or strip application by about 5 to 10㎝, and the direct application of the same hole with the seeds should not be used to cause fatal damage.