Soybean is a common economic crop in China, so it is grown in many areas. However, if you want to grow soybeans, you need to do basic management tasks such as water, fertilizer, light, temperature, etc. When is soybean fertilized? How much is an acre? Is the fertilizer suitable? How to apply fertilizer?

First, the importance of topdressing soybeans and the law of fertilizer demand

Topdressing is a fertilizer applied to supplement the lack of base fertilizer during crop growth, depending on the nutrient demand of the crop. Topdressing is extremely important for high yields of soybeans. In order to meet the nutrient requirements of growth and development in a timely manner, topdressing fertilizers, such as chemical fertilizers and decomposed organic fertilizers, are applied. Soybean topdressing methods include application, ditch application, acupoint application and spraying. The type, quantity, method and frequency of top dressing should be determined according to the weather, soil and soybean growth.

For each 100 kg of soybean seeds, nitrogen absorption is 7.0-9.5 kg, phosphorus is 1.3-1.9 kg, potassium is 2.5-4.0 kg, and the ratio of nitrogen, phosphorus and potassium is 1:0.2:0.4. One-third to one-half of the nitrogen absorbed by soybeans comes from the nitrogen fixation of soybean rhizobium, and the rest comes from soil and fertilizer. Phosphorus and potassium are mainly supplied by the soil. Soybeans also require boron and molybdenum, among which molybdenum is related to the nitrogen fixation capacity of Rhizobium.

The characteristics of fertilizer requirement in different growth stages of soybean are closely related to the growth of plant. The absorption of nitrogen by soybean accounts for 20% of the total absorption in the period from emergence to flowering; the absorption of nitrogen from the flowering stage to the drum stage is 55%. Nitrogen accounts for 25% of soybeans from the maturity stage to the maturity stage.

Soybean absorbs only 15% of the total amount of phosphorus from the emergence to the early flowering stage; the flowering to pod-forming period of soybean accounts for 60%, reaching a peak; the pod-to-drum phase of soybean accounts for 20%.

The absorption of potassium accounted for 32.2% of the absorption of soybean in the flowering stage to the flowering stage, and the absorption ratio of nitrogen and phosphorus was higher than that of the nitrogen and phosphorus. The absorption from the flowering stage to the drum stage accounted for 61.9%; 5.9%. The pod-forming period is the period in which soybeans absorb the most nitrogen, phosphorus and potassium nutrients, and the absorption intensity is large, which easily leads to de-fertilization.

Second, how do soybeans topdress?

Generally, soybeans enter the most vigorous growth stage from the flowering stage, and the plant height, leaf area coefficient and dry matter accumulation are faster, and the required nutrients are also more, but at this time, the available nutrients in the soil usually drop to a low value, and the nutrient supply is insufficient. Therefore, in the early flowering stage of soybean, the quick-acting nitrogen fertilizer can significantly increase the dry matter accumulation and photosynthetic rate, which is an effective measure for high yield of soybean.

The application of nitrogen fertilizer should also be flexibly controlled according to the growth of the plant and the soil fertility. For example, the soybean seedlings are thin and the soil is thin, and the topdressing time should be appropriate in advance to promote vegetative growth and set up a high-yield shelf.

If the seedling stage has been fattened, if the flowering period is still lack of fertilizer, it can be replenished once. If the bean seedling grows robustly, the leaf area coefficient is too large, and the soil alkaline nitrogen content is above 80 mg/kg. It is not necessary to trace the nitrogen fertilizer at the initial flowering stage to avoid the lengthening and lodging.

Apply 10 to 15 kilograms of urea per acre, and use thinner and weaker seedlings to properly chase. Topdressing is better with ditch, and urea can also be applied to the rows. It is best to combine cultivating and irrigation to ensure fertilizer efficiency. Spreading should avoid spreading the fertilizer on the leaves to prevent burns on the leaves.

Phosphate fertilizer is generally used as a base fertilizer application. If phosphorus is deficient, the phosphate fertilizer can be applied to the soybean seedling stage or the early flowering stage. If there is severe phosphorus deficiency, it is still necessary to apply phosphate fertilizer during the pod-forming period. The amount of top dressing is generally applied to 25 kg of superphosphate or other equivalent amount of quick-acting phosphate fertilizer per acre. Soybeans are less likely to chase after the pods. Because phosphorus moves in the soil in a small range, it must be applied to the plough layer, preferably in the ditch; in the soybean blast stage, it is best to use the root spray.

Potassium fertilizer should be chased early. It should be best applied in the early flowering stage of soybean seedlings. Apply 7.5-10 kg of potassium sulphate per acre or other quick-acting potash fertilizer, and apply it to the plough layer.

Soybean topdressing can be combined with watering, cultivating, and soiling. Tillage help suggests cultivating the soil immediately after topdressing to avoid loss of fertilizer.

Third, how to fertilize soybeans?

Foliar application is a method of topdressing other than roots of plants. Generally, a fertilizer solution or dry powder is sprayed on the foliage or back of the crop by a sprayer. Foliar spray can directly absorb fertilizer through the leaves and transport it quickly to various organs to participate in the biochemical process in the body, which can significantly improve yield and improve quality. Because this method does not pass through the soil, nutrients are not fixed by the soil and the fertilizer utilization rate is high. But this is only a way of topdressing outside the roots, not a substitute for root topdressing.

Soybeans are commonly used as foliar spray fertilizers such as urea, potassium dihydrogen phosphate, etc., the concentration of spraying is 1% to 2%; the concentration of trace elements boron, manganese, copper and zinc salts is generally 0.1%, molybdenum The concentration of the salt spray is 0.01% to 0.05%.

The proportion of soybean foliar spray topdressing is generally 0.5 kg of urea, 0.5 kg of potassium dihydrogen phosphate or 1.5 kg of superphosphate, 0.75 kg of potassium sulphate water leaching solution, 50 kg of water, sprayed on the leaves of plants. Soybean leaf spray should be carried out after 4 pm on a cloudy or sunny day. Spraying on the back of the leaves of the plants is more efficient than the front side. It is generally absorbed and utilized by soybean plants 2 to 8 hours after spraying. (The internet)

This article URL: How to fertilize soybean cultivation? What are the molybdenum fertilizers required for fertilization time and fertilization?

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