In recent years, some large planting farmers in the northeast region like to use their own mixed fertilizers, but they often encounter various unpredictable problems during the mixing process. In order to help farmers overcome the technological barriers related to the application of fertilizers, here is a brief description of the principles of common single fertilizers.
The main problem encountered in the mixed application of simple fertilizers is the defect from its physical properties, resulting in many inconveniences in storage, transportation and field application. For example, agglomerates, dusts, secondary separation of particles, and excessive water absorption. Therefore, growers should understand the common physical properties of nitrogen, phosphorus, and potassium fertilizers, especially the common sense of hygroscopicity, agglomeration, granularity, and pressure resistance.
Fertilizer and hygroscopicity are as small as possible
Hygroscopicity refers to the ability of chemical fertilizers to absorb moisture from the air. The agglomeration is related to the moisture absorption of the surface of the single fertilizer particle, and the fertilizer with high moisture absorption is easy to agglomerate. These two properties are very unfavorable for the storage, transportation and application of chemical fertilizers. The principle of mixed application of fertilizers requires that the smaller the hygroscopicity and the caking property, the better.
However, most of the water-soluble fertilizers will absorb the moisture of the air more or less, but there are great differences among different varieties. The hygroscopic point at room temperature indicates that the low moisture absorption point means that the hygroscopicity is large and the fertilizer is easily deliquescent. Among common fertilizers, calcium nitrate and ammonium nitrate are the lowest (42.7% and 66.5%, respectively); ammonium chloride, urea, and potassium chloride are medium (79%, 82%, and 84%); ammonium sulfate and superphosphate Calcium and potassium sulfate are higher (86%, 91%, 95%). The above data is the moisture absorption point of the single fertilizer, and the moisture absorption of the fertilizer after mixing is significantly higher than that of the simple substance, and it is more prone to deliquescence.
Chemically compatible single-element fertilizers should be selected
In the process of mixing two or more simple fertilizers, there are often some chemical reactions. Some of these reactions are benign. Some of them may lead to increased hygroscopicity resulting in agglomeration or the fixing of effective nutrients to reduce fertilizer efficiency. Therefore, a chemically compatible single fertilizer is selected for mixed application.
If chemically non-mixable two element fertilizers are blended together, they generate heat, increase humidity, evolve gas, or form agglomerates. For example, the mixing of calcium and calcium carbonate can lead to the loss of ammonia. Ammonium nitrate and urea are two kinds of simple fertilizers that are completely incompatible. If they are mixed and piled together, the hygroscopicity of the mixture will be greatly enhanced, and even dissolution will occur. Unable to apply. Urea and superphosphate are two types of fertilizers that are mixed in a limited amount. They can be mixed and used without storage. Especially in the high temperature and high humidity season in summer, it is impossible to wait for the night after the mixture is applied to the soil. If the two are mixed overnight, the mixture will slowly deliquesce and become a paste. In the compound fertilizer processing plant, the free acid in the superphosphate is neutralized with ammonium to form an aminated superphosphate, which can be mixed with urea.
Whether the common single fertilizers can be mixed can be listed in the following table, and related information can be found on the table. In common simple nitrogen fertilizers and phosphate fertilizers, superphosphate and ammonium sulfate have good material properties and can be directly used as seed fertilizers or basal fertilizers; while superphosphate and ammonium bicarbonate are finitely compatible, and the two must be mixed in a certain proportion. , And with the mix as a base fertilizer, do not store. The optimal ratio of the two is that the superphosphate:ammonium bicarbonate is approximately equal to 7:3; if too much ammonium bicarbonate is used, the proportion of water-soluble phosphorus in the superphosphate is liable to decrease. Phosphate fertilizer can be used as a base fertilizer once in the soil, and less ammonium bicarbonate can be set aside for later dressing.
Mixed fertilizer particle size must match
When several granular fertilizers are mixed and applied, delamination may occur during storage, transportation and application, resulting in uneven fertilization and poor fertilizer efficiency. The delamination problem is due to the uneven size of different fertilizer particles. Therefore, the particle size of the fertilizer to be blended must be controlled, and only fertilizers with a matching particle size can achieve uniform fertilization and the fertilizer effect can be guaranteed.