According to the calculation of the amount of fertilizer required for cabbage growth and the supply capacity of soil nutrient, combined with the current actual level of fertilization of cabbage, comprehensive analysis was carried out to determine the amount of fertilization: (1) The late-maturing variety was selected in the middle and upper-grade yield of 8000 kg, and 7500 kg of high-quality farmyard manure was applied per mu. 23 kg of nitrogen, 10.5 kg of phosphorus, 15 kg of potassium; (2) medium-sized land of 6,000 kg, selected early-maturing varieties, 6500 kg of high-quality farmyard manure, 20 kg of nitrogen, 9 kg of phosphorus, 13 kg of potassium; (3) inferior land of target yield, Generally choose early-maturing, medium-early-maturing varieties, 5,000 kg of farmyard manure, 16 kg of nitrogen, 3 kg of phosphorus, and about 9 kg of potassium.
Second, fertilization technology
(1) Apply enough base fertilizer. Cabbage has a long growing season and requires a large amount of high-quality organic fertilizer with long-term fertilizer efficiency. Therefore, it is very important to apply a large amount of manure as a base fertilizer. Generally, the application is not less than 5,000 kg. Before cultivating land, first sprinkle 60% of the manure in the ground and pour it into the soil. Before the shovel, spread 40% of the manure on the ground and into the shallow soil. Then add calcium phosphate or compound fertilizer, and apply it together when applying fertilizer. The amount of each acre is 50 kg to 75 kg.
(2) Sowing and applying the seedling fertilizer. In order to ensure sufficient nutrients in the seedling stage, it is necessary to apply quick-acting fertilizers as “lifting fertilizerâ€. Apply 5 kg to 8 kg of ammonium nitrate per acre, apply to the seeding point, mix well with the soil before the live broadcast, and then water and sow.
(3) Fertilizer. The lotus leaf produced during the rosette period is an organ that will produce a large number of photosynthetic products in the future during the ball-forming period. Full fertilization and watering is the key to ensure the strength of the rosette leaves, but at the same time, it is necessary to prevent the rosette leaves from growing and causing the heart to end. "Fat fertilizer" should be applied when there are a few plants in the field to start the group, generally 800 kg - 1500 kg of manure, 50 kg - 100 kg of plant ash, or 10 kg - 15 kg of ammonium nitrate, phosphorus and potassium fertilizers 7 Kilogram - 10 kg. Live cabbage should be fertilized and covered with soil in a small ditch 8 cm - 10 cm on the edge of the plant. The transplanted cabbage will be fertilized into the ditch, mixed with the soil and planted with the seedlings. If there is a long-term phenomenon in the late rosette, the "small seedling" measures must be taken.
(4) Shooting fertilizer. The ball-forming fertilizer is the period of product formation, and the assimilation is the strongest. Therefore, it requires a large amount of fertilizer and water. Applying the fertilizer with long-lasting fertilizer effect from 5 days to 6 days before the package, especially the application of potassium fertilizer, can be combined with the application of “Hongjie†brand vegetable special fertilizer. Generally, 20 kg of ammonium nitrate is applied, 10 kg to 15 kg of superphosphate and potassium sulfate, and 50 kg to 100 kg of grass ash. In order to make the nutrients lasting, it is best to mix the fertilizer with the decomposed manure, and it is appropriate to apply a deep groove of 5 cm to 10 cm between rows. This topdressing has the effect of enriching the inside of the leaf ball and promoting irrigation.
There are more than 10 grades of 3.6,4.6,4.8,5.6,6.8,8.8,9.8,10.9,12.9 in the performance grades of bolts for Steel Structure Connection, the bolts of grade 8.8 and above are made of low-carbon alloy steel or medium-carbon steel and heat-treated (quenched and tempered) , commonly known as high-strength Bolts, the rest are commonly known as ordinary bolts. Bolt performance grade label has two parts of digital composition, respectively, the nominal tensile strength of bolt material and yield strength ratio. For example,
Performance grade 4.6 bolt, the meaning is: 1, Bolt Material Nominal tensile strength up to 400MPa class, 2, bolt material yield strength ratio is 0.6; 3. The nominal yield strength of bolt material is 400 × 0.6 = 240mpa performance grade 10.9, the material after heat treatment can reach: 1. The nominal tensile strength of Bolt Material is 1000MPa; 2. The yield strength ratio of bolt material is 0.9.3. The nominal yield strength of bolt material is 1000 × 0.9 = 900MPA. The meaning of the performance grade of bolt is the international standard, its performance is the same, the design can only choose the performance grade. The so-called strength grade 8.8 and 10.9 means that the shear stress grade of the bolt is 8.8 GPA and 10.9 GPA8.8 nominal tensile strength 800N/MM2 nominal yield strength 640N/MM2, x * 100 = The tensile strength of the Bolt, x * 100 * (y/10) = the yield strength of the bolt (because according to the designation: Yield strength/tensile strength = y/10) as grade 4.8 then the tensile strength of the Bolt is: 400 MPA yield strength: 400 * 8/10 = 320 MPA
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