Basic principles of chemical fertilizer use
(2) Application in combination with organic fertilizers. Because the characteristics of organic fertilizers are slow, stable, long and nutrient-rich, and the characteristics of chemical fertilizers are fast, fast, short, and single nutrient. The two can be used together to make up for each other's strengths and enthusiasm. There is also a stamina to balance the supply of crop nutrients. The combination of organic fertilizer and chemical fertilizer can strengthen the activities of soil microorganisms, promote the further decomposition of organic fertilizers, release a large amount of carbon dioxide and organic acids, and contribute to the dissolution of poorly soluble nutrients in the soil, and supply and absorb crops. The results of the national fertilizer test network test showed that the combination of organic fertilizer and inorganic fertilizer had the best effect on yield increase, which was higher than that of chemical fertilizer alone.
(3) Rational application of NPK. The absorption of various nutrients by crops is regularly absorbed in a certain proportion. Various nutrients have specific effects and cannot be replaced, but they can promote each other. For example, nitrogen fertilizer can promote the absorption of phosphorus, and potassium fertilizer can improve the fertilizer efficiency of phosphate fertilizer, and at the same time promote the absorption and utilization of nitrogen by crops. The application of NPK fertilizer can play a coherent effect and greatly improve the utilization rate of fertilizer.
(4) Apply trace element fertilizers according to local conditions. The amount of trace elements absorbed by plants is limited, but it cannot be lacking. The lack of a certain trace element in plants causes obstacles to vegetative growth and reproductive growth, and even deadlocks die. The lack of trace elements is closely related to the soil supply status and the situation of crop absorption and utilization. The amount of trace elements provided by different soils is different, and the absorption of trace elements by different crops is also different. Thus, the application of trace elements must be targeted. Some trace elements are not used properly and can cause toxicity to plants.
(5) Determine a reasonable fertilization method. Fertilizers generally have high nutrient concentrations, high water solubility, and are prone to loss. Therefore, the amount of fertilization should not be excessive. Excessive fertilization is not only uneconomical, but also easy to cause lodging to reduce production. Nitrogen fertilizer should pay attention to deep application to reduce the loss of nitrogen volatilization. Nitrogen fertilizer should also be divided into fertilization according to the condition of the soil. Do not directly contact seeds, young shoots and leaves to prevent burning and burning. Phosphate fertilizer is easy to fix in the soil, with little mobility and long aftereffect. Therefore, the application of phosphate fertilizer is generally used as a base fertilizer, and it should be applied to the root of the crop as much as possible during application, and should not be applied. Potassium fertilizer is generally used as a base fertilizer, and there is also a small amount of top dressing or foliar fertilizer. Trace element fertilizer can be used as base fertilizer, seed fertilizer or top dressing. There are various methods such as spraying, dipping, mixing, acupoints, sprinkling, and dipping.
Although there are many types of tapping screws, they all have the following similarities:
(1) are generally made of carbonized carbon steel (accounting for 99% of total production). It can also be made of stainless steel or non-ferrous metals.
(2) The product must be heat treated. Carbon steel tapping screws must be carbonized and stainless steel tapping screws must be solution hardened. In order to make tapping screws to meet the requirements of the standard of mechanical properties and performance.
(3) The product surface hardness is high, the core toughness is good. That is, "soft inside strong outside". This is a major feature of tapping Screw performance requirements. If the surface hardness is low, it can not be screwed into the matrix; If the core toughness is poor, a twist will break, can not be used. So "inside soft outside steel" is self-tapping screw to meet the use of performance, very important requirements.
(4) The surface of the product needs surface protection treatment, generally electroplating treatment. Some product surface must be treated by phosphate (photostatting), such as wall panel self - tapping screws for photostatting.
(5) Production by cold heading process. It is recommended to use high-speed cold heading machine and high-speed wire rolling machine or high-speed planetary wire rolling machine. High speed is emphasized here to ensure product quality. Only the head of tapping screw produced by high-speed machine is well formed and the thread quality is high.
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