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Today, it is required to rationally apply diammonium phosphate according to the characteristics of diammonium phosphate, and adjust the dosage and application method according to the change of available phosphorus content in soil. According to the principle of balanced fertilization, the effect of increasing the production of ammonium phosphate is fully utilized. The technology of phosphate fertilizer application should be adjusted accordingly.
Diammonium phosphate is a low-nitrogen and high-phosphorus binary high-concentration compound fertilizer
Diammonium phosphate contains N18%, and contains P2O546% of total nutrients reaching a high concentration of 64%. It has the characteristics of low nitrogen, high phosphorus and no potassium in nutrient supply. It is particularly effective on soils that are deficient in phosphorus. In the early 1980s, soils in the vast agricultural areas of northern China were generally deficient in phosphorus. The 1000-grain weight of food crops was lighter. Farmers applied diammonium phosphate to various crops at the time, and the yield-increasing effects were obvious. Therefore, farmers in North China, Northeast China and Northwest China like to apply this fertilizer. By the early 1990s, farmers in the northern region began to reflect that after years of application of diammonium phosphate, the fertilizer effect was not prominent. At the same time, the soil fertility survey and test data of various places also showed that the effective phosphorus level in the surface soil of the middle and high-yield agricultural areas increased year by year, phosphorus accumulated in the soil, and the phosphate fertilizer had the aftereffect. This indicates that the characteristics of phosphate fertilizer and nitrogen fertilizer are different. The nitrogen fertilizer is active in nature. After being applied to the farmland, there are losses such as volatilization, leaching and denitrification, and the phosphate fertilizer is inactive. In the farm soil, not only the migration is slow, but the conversion product activity is low. The utilization rate in the quarter is very low, and the cumulative utilization rate after application is high.
Principle of rational application of diammonium phosphate
Ammonium phosphate fertilizer can play an important role. The use of precision ammonium phosphate as a seed fertilizer can represent a "smart". In the spring farmland, the phosphorus in the soil nutrient pool is slow to be activated, and the crop seedling period is the critical period of phosphorus nutrition. It is sensitive to the reflection of phosphorus and is prone to phosphorus deficiency. At this time, phosphorus deficiency, crop seedlings are not strong, and the resistance is poor. . The farmer said: "There is money to buy seeds, no money to buy seedlings", and it is difficult to obtain high yields later. There are two key technologies for using precision ammonium phosphate as seed fertilizer. The first is to control the dosage at 5 kg/mu. Second, the application position should be applied 2 to 3 cm below the oblique angle of the seed. Do not touch the fertilizer. For many years, farmers in the Sanbei area have been accustomed to applying diammonium phosphate fertilizers to spring maize, soybean and cotton crops, which has become a fixed measure for high-yield projects.
Ammonium phosphate is suitable for use as a base fertilizer. The large amount of phosphorus in the base fertilizer can ensure the development of grain and melon and fruit in the late growth stage of the crop, and the yield is guaranteed. Since the phosphorus in the diammonium phosphate is three times that of the nitrogen, it can be used alone for the base fertilizer of the legume crop which has a strong nitrogen-fixing ability, and the application amount is preferably 8 to 10 kg. When using diammonium phosphate as the base fertilizer on other crops, it is necessary to equip with an appropriate amount of elemental nitrogen and potassium fertilizer to adjust the ratio of nitrogen and potassium. The role of crop base fertilizer is mainly to supplement the nutrition in the middle and late stages. Therefore, ammonium phosphate should be applied deeply. The phosphorus in ammonium phosphate is poorly transported in the soil, and the absorption efficiency can be improved only by applying the distribution area of ​​the main root of the crop. The depth of application of different crops should be different, especially for fruit trees requiring 40-60 cm, vegetables 15-20 cm, and food crops 20-30 cm.
The amount of base fertilizer varies depending on the type of crop and the fertilization status of the forehead. For example, farmland with organic fertilizer can be applied less; the plot of ammonium phosphate can be applied less or modified to apply ternary compound fertilizer. The recommended recommended dosage of ammonium phosphate for general grain crops is about 10 to 12 kilograms, and cotton is 12 to 16 kilograms per mu. Regarding the adjustment of nitrogen and potassium fertilizers and increasing the proportion of nitrogen fertilizers, it is not necessarily all added to the base fertilizer, and nitrogen can be added to the top dressing, and the effect will be better.
Although diammonium phosphate is quick-acting, it is not suitable for top dressing and flushing. Because the granular diammonium phosphate is applied to the surface during topdressing, the dissolution is slow and little, and the dissolved phosphoric acid has poor migration to the lower layer of the soil. It is fixed while moving, and the fixed product is water insoluble. Not absorbed by the root system, lost the effect of fertilizer. If diammonium phosphate is used as water for fertilizer, the more expensive phosphorus will be taken away from the surface runoff, or enriched on the surface, and the roots of the crop will be mainly released underground. The root system is not enough for fertilizer, the fertilizer efficiency is poor, and the surface loss of phosphate fertilizer is caused. , polluted water environment. This two-way problem should not happen.
In short, diammonium phosphate is a good fertilizer, it is very effective in the soil with phosphorus deficiency, but its nutrients are not comprehensive, it needs to supplement nitrogen and potassium nutrients, and implement balanced fertilization. Also, do not use diammonium phosphate for top dressing and flushing.
(Senior Consultant of Sinofert, Professor of China Agricultural University, Cao Yiping)
Since the 1990s, the application of DAP has been recognized in agricultural planting in the Three North Region of China. With the rapid growth of domestically produced ammonium phosphate, the application of a large amount of phosphate fertilizer, from 1981 to 2000, China's grain field Soil phosphorus increased at a rate of 11%, and soil total phosphorus and available phosphorus increased by an average of 0.21 g/kg and 5.7 mg/kg. The area of ​​phosphorus-deficient soil has been reduced from 67% in the 1980s to below 50%, and the area of ​​phosphorus-rich soil has increased from 7% to 15%. Through the application of phosphate fertilizer for many years, the level of available phosphorus in the soil of northern agricultural areas in China has generally increased, especially in high-yield farmland and vegetable crops, and the level of available phosphorus in the surface of 20 cm soil is very high. This indicates that in the case of maintaining crop yields in the Sanbei area, the available phosphorus in the soil has accumulated, resulting in the effect of applying ammonium phosphate in successive years is not as good as the initial effect. This phenomenon is wrongly directed to the continuous application of fertilizer. Increase, the application method is unsuitable to expand, for example, some use up to 50 kg, and some use diammonium phosphate as top dressing and flushing.
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