A bogey mixed with alkaline fertilizer or urea applied at the same time must be converted into ammonia nitrogen will produce fertilizer effect, and ammonia nitrogen in alkaline conditions, most of the nitrogen will become volatile ammonia, so urea can not With lime, grass ash, calcium magnesium phosphate and other alkaline fertilizers mixed application or simultaneous application. In general, in summer and autumn, urea and alkaline fertilizers should be staggered for 3 to 4 days, and winter and spring should be staggered for 7 to 8 days.
The second taboo for seed dressing urea in the production process, often produces a small amount of biuret, when the biuret content exceeds 2% will be toxic to the seeds and seedlings, such urea into the seeds and seedlings will make the protein Denaturation, affecting seed germination and seedling growth, it is not suitable for seed fertilizer. If it must be used as a seed fertilizer, avoid seed and fertilizer contact and control the amount.
After the three bogey waters, the urea is immediately irrigated with amide nitrogen fertilizer. It must be converted into ammonia nitrogen before it can be absorbed and used by the crop roots. The conversion process may vary depending on the soil quality, moisture, temperature, and other conditions. The time varies from 2 to 10 The days will be completed, and if irrigation is done immediately after application or if the dry land is applied before heavy rain, urea will be dissolved in the water and lost. Generally summer and autumn should be 2 to 3 days after application to irrigation, winter and spring season should be watered 7 to 8 days after application.
Four bogey surface application of urea on the surface of the ground, at room temperature to be used after 4 to 5 days of transformation can be used, most of the nitrogen easily volatile in the ammoniation process, the general practical utilization is only about 30%, if in the alkali In the soil with high soil and organic matter content, nitrogen loss will be faster and more. And shallow urea, easily consumed by weeds. Deep application of urea, melting of fertilizer in soil, fertilizer in a moist soil, is conducive to the exertion of fertilizer efficiency. For topdressing should be applied next to the seedlings or ditch applied on the seedling side, the depth should be about 10 ~ 15cm. In this way, urea is concentrated in the root-dense layer, which facilitates the absorption and utilization of crops. Tests have shown that deep application of shallower application can increase the utilization of urea by 10% to 30%.
5. Avoid excessive use of large amounts of urea nitrogen, the amount should not be too large, so as to avoid unnecessary waste and "fat harm." Generally, 5 to 15 kg per mu, and 15 to 20 kg per mu for paddy fields. Excessive application can not be absorbed by the soil before it is converted to ammonium bicarbonate. It is easily leached by rainwater and can easily harm crops. At the same time, too much urea is applied, most of which are lost and enter the groundwater, which will lead to nitrogen pollution in the water, resulting in the deposition of nitrite and seriously affecting the safety of people and livestock.
Six bogey high concentrations of foliar spray in all nitrogen fertilizer, urea is the best foliar fertilizer. When urea is sprayed, the amount and rate of protein synthesis in the crop exceed those of other nitrogen fertilizers. However, when foliar spraying, avoid excessive concentration of urea solution, otherwise it will burn the leaves and poison the plants. Usually 2% is suitable for the concentration of corn, rice, etc.; 0.5%~1.5% of vegetables and melons are suitable.
Seven bogey applications too late to apply urea too late, is not conducive to the exertion of fertilizer efficiency, easy to cause crops greed green late, it should generally be applied 4 to 7 days earlier than other nitrogen fertilizer application.
Eight bogey single application of urea is the effective component of nitrogen, a single nutrient, and crop growth and development requires a variety of nutrients. Therefore, urea should be combined with organic fertilizers, phosphorus, and potassium fertilizers to meet the needs of crops for various nutrients. And urea and organic fertilizers and chemical fertilizers are properly mixed and can effectively increase their utilization. If urea is mixed with superphosphate, unstable ammonium bicarbonate can be converted into stable ammonium phosphate, so that the natural volatilization of nitrogen is greatly reduced. The combined application of urea and organic fertilizers produces organic acids during the fermentation process, which also accelerates the conversion and decomposition of urea, and is rapidly absorbed by crops to increase the utilization of urea.
Nine bogey applied to celery on the celery during the entire growth need to apply a lot of nitrogen fertilizer, but not urea. Because topdressing urea will make the celery fiber thicker and thicker, the plants will age, grow slowly, and will have a bitter taste when eaten, resulting in poor quality. Celery is suitable for applying ammonium bicarbonate, ammonia, and decomposed organic fertilizers to improve quality.