How to fertilize rapeseed scientifically, and can the snow-topdressing technique be used?
Rapeseed is an oilseed crop and is grown fairly widely in our country. Its young flowering stems can also be eaten, with a crisp texture and a distinctive taste. In addition, some places in our country attract tourists to come and take photos and admire the scenery by planting large fields of rapeseed. During rapeseed cultivation, how should fertilizer be applied scientifically? Can the snow-topdressing technique be used?
1. How should rapeseed be fertilized scientifically?
1. Fertilize according to the field
Rapeseed fertilization varies. To achieve high yield, the above fertilization levels should be increased by 15%-20%. The specific amount of fertilizer applied can be based on soil texture, soil fertility, seedling condition, whether base fertilizer was applied, the amount applied, and so on, and fertilizer can be supplied according to the conditions of the field. The specific amount can be accurately topdressed and supplemented according to the demand patterns for each nutrient above.
2. Fertilization time
Rapeseed is a crop that accumulates nutrients in the early stage. Although its demand for phosphorus is not as great as that for nitrogen fertilizer and potassium fertilizer, it is very sensitive to it. If phosphorus is deficient in the later stage, it will have a great impact on the nutrition, growth and development, and yield of rapeseed. Therefore, the fertilization strategy for directly sown winter rapeseed is to promote early and stabilize later, that is, 70% of the nitrogen fertilizer, all of the phosphorus fertilizer, potassium fertilizer and boron fertilizer are used as base fertilizer or seedling fertilizer, and the remaining 30% of the nitrogen fertilizer is applied as stem fertilizer.
The bolting and flowering stage is the period of maximum nutrient efficiency for rapeseed, and the fertilizer requirement accounts for the largest proportion in its entire life. Therefore, from bolting to flowering, fertilizer must be topdressed in time, so that it is applied at the bud stage for use at the flowering stage.
3. Fertilization methods
Topdressing for rapeseed is just as important as base fertilizer, and attention must be paid to balanced fertilization. In order to promote tillering and strong seedlings, apply 3-5 kg of urea as topdressing in rapeseed fields with fewer than 5 leaves to promote rapeseed seedling growth. In addition, pay attention to supplementing boron, phosphorus and potassium fertilizers. For fields where boron fertilizer was not applied, supplement 1-1.5 kg of boron fertilizer per mu. For fields where phosphorus and potassium fertilizers were not applied, supplement 5-8 kg of potassium chloride per mu or supplement 20-25 kg of phosphorus fertilizer, or 10-15 kg of ternary compound fertilizer.
When rapeseed flower buds differentiate, apply the rosette-stage fertilizer. At this time, mainly quick-acting nitrogen fertilizer should be applied, and 5-7 kg of urea can be applied per mu; at the stage, apply 5-8 kg of urea per mu, together with 2.5-5 kg of diammonium phosphate, or apply 15-20 kg of ternary compound fertilizer; fertilization at the rapeseed flowering stage can be done by foliar spraying. During the flowering and pod-setting period, spray 50 kg of 0.1%-0.2% urea or 0.2% potassium dihydrogen phosphate solution per mu, and spray boron fertilizer 1-2 times before flowering. Of course, the topdressing amount for different fields should be adjusted according to the seedlings.
2. Can winter rapeseed use the snow-topdressing technique?
The snow-topdressing technique is a technique that uses winter snowfall to topdress dryland-grown crops such as winter rapeseed and winter wheat, especially fields with poor soil fertility and weak seedling condition before winter.
Specific method: when snowfall reaches about 10 cm, evenly broadcast a quick-dissolving nitrogen fertilizer that does not volatilize easily (such as urea) on the snow, generally applying 7.5-10 kg of urea per mu, and fields with poor soil fertility conditions may appropriately increase the amount. Farmers can also, according to the weather forecast, broadcast it into the field in advance before snowfall, and after snowfall the chemical fertilizer will be covered, so that it melts together with the snow and infiltrates into the soil.
Precautions: if the snowfall is too little, the chemical fertilizer is difficult to dissolve completely, the expected effect cannot be achieved, and fertilizer loss is caused.
Effect: after overwintering crops turn green in spring, as the temperature rises, growth speeds up, and some crops carry out vegetative growth and reproductive growth at the same time, with very high requirements for water and fertilizer. Winter fertilization on snow achieves the use of winter fertilizer in spring, solves the phenomenon of fertilizer deficiency in spring in fields with poor soil fertility, promotes the transformation and upgrading of seedling condition, and lays the foundation for high yield.