Essentials of applying extra-root fertilization techniques for crops

First, according to the characteristics of the fertilizer, select the type of fertilizer suitable for external application.

Fertilizers for good external fertilization effects include urea, potassium dihydrogen phosphate, potassium nitrate, potassium sulfate, and ammonium sulfate. Leachate of superphosphate and grass ash, ammonium metaphosphate and most trace element fertilizers. Some highly volatile fertilizers such as ammonia, ammonium bicarbonate and fertilizers containing chloride ions such as ammonium chloride, potassium chloride, etc., are not suitable for external fertilization because they cause large fertilizer losses, while others are crops. Have an adverse effect.

Second, according to the type of crop and growth period, select the amount and concentration of fertilizer.

The suitable concentration of crop root fertilization is generally: urea 1-2%, potassium dihydrogen phosphate 0.3-0.5%, superphosphate calcium leaching solution 3-5%, ammonium molybdate 0.01-0.1%, ammonium metaphosphate 2-3%, Borax 0.1-0.2%, zinc sulfate 1%, fertilizer solution per mu is 50-60 kg, cotton, rapeseed, beans, vegetables and other dicotyledonous crops, large leaf area, thin cuticle, nutrients in solution easy to be Absorption, therefore, the concentration of spray fertilizer for such crops should be appropriately lower; the leaf area of ​​monocotyledonous crops such as rice, wheat, corn, etc. is relatively small, the degree of silicidation of leaves is high, and the nutrient composition is difficult to be quickly absorbed by the leaves, so the fertilizer is sprayed. The concentration of the fertilizer must be appropriately increased.

Third, according to the climatic conditions, choose the appropriate time for spraying fertilizer.

Many experiments have shown that root fertilization is carried out in relatively humid weather, and the leaves are kept moist for 30-60 minutes to obtain better fertilizer efficiency. In order to extend the moisturizing time of the fertilizer solution on the foliage of the plant as much as possible, the fertilization outside the root is best selected when the air is wet or dew in the morning and evening, and the cloudy day can be sprayed all day, but the effect of spraying in the evening is the most good. If a small amount of adhesive, such as washing powder, neutral soap or 885 fertilizer and drug synergist, is added to the fertilizer solution, the surface tension of the fertilizer solution can be reduced, the contact area of ​​the fertilizer solution and the blade can be increased, and the spraying effect can be improved.

4. Determine the number of sprays based on the mobility of the fertilizer in the crop.

According to the relevant test reports, the nitrogen and potassium fertilizers have strong mobility in the crops, so it can be sprayed once in the critical period of crop growth; the mobility of phosphate fertilizers is inferior to that of nitrogen and potassium fertilizers, and must be sprayed according to the growth of crops. 1-2 times; only partially moved zinc, molybdenum, manganese, copper fertilizer and non-moving boron, calcium and other micro-fertilizers in the crop body, generally should be sprayed 2-3 times continuously.

5. According to the biological characteristics of the crop, choose the best spray site.

The green stems and leaves of crops are reasonable parts of spray fertilizer, especially the green functional leaves that grow young and grow vigorously, and the fertilizer effect is the best. It is worth noting that the epidermal tissue in the front of the dicotyledonous leaves is a layer of closely arranged palisade tissue with small intercellular spaces. The nutrients in the fertilizer solution are difficult to break through the "blocking" and penetrate; but the back of the leaves are different, the epidermis tissue is all loosely arranged sponge tissue, the cell gap is large, the nutrient content in the fertilizer liquid is easy to enter and is Quickly absorbed. Therefore, when spraying the dicotyledonous crops, it is equally sprayed on the front and back of the leaves, while the monocotyledonous crops only need to spray the fertilizer from the top to the bottom of the leaves.

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