How to use urea for the best results? Master the correct fertilizing method
How can urea be used for the best results? What should be noted when applying urea? We would also like to ask knowledgeable readers to help explain. Urea is a high-concentration nitrogen fertilizer, a neutral quick-acting fertilizer, and can also be used to produce various compound fertilizers. Urea leaves no harmful substances in the soil, and long-term application has no adverse effects. Correct use of ur...
How can urea be used for the best results? What should be noted when applying urea? We would also like to ask knowledgeable readers to help explainUrea is a high-concentration nitrogen fertilizer, a neutral quick-acting fertilizer, and can also be used to produce various compound fertilizers. Urea leaves no harmful substances in the soil, and long-term application has no adverse effects. Only by using urea correctly can its fertilizer effect last longer. Zhongdi Network has compiled the application methods for urea, listed in detail below for readers' reference.
Application method one: Determine the topdressing amount according to soil fertility:
Practice has proved that increasing the amount of fertilizer applied to medium- and low-yield fields can significantly increase yields. For high-yield fields, maintaining a general fertilization level is sufficient. Generally, on the basis of applying sufficient farmyard manure and chemical fertilizer as base fertilizer, taking the two major crops of corn and sorghum as examples, on high-fertility soil, apply 20 kg per mu as topdressing; on medium-fertility soil, apply 23 kg per mu as topdressing; on low-yield soil, 27 kg should be applied as topdressing.
Application method two: Use as topdressing during the peak nutrient period of the crop:
The main role of topdressing is to use fertilizer to regulate the crop's growth and appearance, meet the crop's nutritional needs in the middle and late growth stages, and achieve the goal of increasing yield. The key to improving the utilization rate of topdressed chemical fertilizer is to grasp the critical period and the period of maximum efficiency for nutrient absorption by various crops, and try to topdress during the crop's peak nutrient period so as to improve fertilizer utilization. Corn should be topdressed from the jointing stage to the large trumpet stage; sorghum from the jointing stage to the booting stage; rice from the greening stage to the tillering stage; sunflower at the squaring stage; wheat at the three-leaf stage; soybean at the early flowering stage.
Application method three: Apply deeply and cover with soil:
Through experiments, after urea is applied to the soil surface at normal temperature for 4-5 days, most of the nitrogen is ammoniated and volatilized, and its utilization rate is only about 30%, especially on the surface of calcareous and alkaline soils, where the ammonia volatilization loss is even more serious. Therefore, when using urea to topdress dryland crops, it is best to dig holes or open furrows and apply it deeper than 10 cm, so that the urea is in moist soil, which is conducive to the transformation of urea and also helps ammoniacal fertilizer be adsorbed by the soil, reducing volatilization loss. When using urea to topdress rice, the water layer must not exceed 3-5 cm at its deepest.
Application method four: Keep a certain distance from the crop roots when applying:
Because urea has a high nitrogen content, a high nutrient concentration, and strong hygroscopicity. Therefore, when topdressing, prevent applying urea near the crop roots, and even more, do not let urea fall into the crop's heart leaves, so as not to burn the seedlings and affect growth. Be sure to keep a certain distance from the crop.
Application method five: Apply urea in advance:
Because urea is a low-molecular organic compound, after being applied to the soil it must undergo an ammoniation process and be converted into highly volatile ammonium carbonate before it can be absorbed by crop roots. Therefore, when using urea to topdress crops, it should be applied about 7 days earlier than other nitrogen fertilizers.
Application method six: Do not mix with alkaline fertilizers:
Urea is a neutral fertilizer, and when topdressing, it must never be mixed and applied at the same time with alkaline chemical fertilizers, so as to prevent reducing the fertilizer effect. If mixing with alkaline fertilizers is unavoidable, the fertilization dates should also be staggered, generally 3-5 days apart. However, when urea is mixed with fertilizers such as potassium chloride, phosphate rock powder, and superphosphate, its yield-increasing effect is very significant.
Application method seven: Do not irrigate immediately after applying urea:
After urea is applied to the soil, before it is decomposed and transformed, it cannot be adsorbed by the soil. If irrigation is carried out immediately after topdressing, it will cause a large loss of urea. If the soil is severely short of water and irrigation is absolutely necessary, small amounts of frequent irrigation should also be used, and flooding irrigation must be avoided. When topdressing rice, the characteristic that urea is highly mobile before transformation should be taken into account, and even more, do not irrigate immediately after topdressing. Generally, one small irrigation 3-5 days after topdressing is suitable.
Application method eight: Use as foliar topdressing (leaf spraying):
Urea causes little damage to crop leaves, is easily soluble in water, has strong diffusibility, is easily absorbed by leaves, and after entering the leaves is not likely to cause plasmolysis, so it is very suitable for foliar topdressing. However, urea with a biuret content not exceeding 2% should be selected to prevent damage to the leaves.
The concentration of urea used for foliar topdressing varies depending on the crop type, for example, the concentration for foliar topdressing of grass-family crops is 1.5%-2%; the concentration for foliar topdressing of dicotyledonous crops is 1%, and during the crop flowering period the concentration should be even lower.
Generally, the amount of urea used for foliar topdressing per mu is 0.5-1.5 kg. The spraying time is best after 4 p.m., when transpiration is low and the leaf stomata gradually open, and the diluted urea solution can basically be completely absorbed overnight, greatly improving the utilization rate of urea.
What are the common nitrogen fertilizers
Is large-granule urea good