Three key links in the production of organic-inorganic compound fertilizers

Organic fertilizers are full of nutrients, but the concentration is low and the fertilizer efficiency is slow. Chemical fertilizers have high nutrients and quick results, but long-term application will cause soil hardening and acidification. Organic-inorganic compound fertilizer is a new type of fertilizer made from fermented organic materials such as animal manure and plant residues, adding some chemical fertilizers, fully mixing and then granulating. It not only has the advantages of fast fertilizer efficiency of inorganic fertilizer, but also has the advantages of organic fertilizer to improve soil and long-lasting fertilizer effect. It can make up for each other by adjusting each other, so as to maintain and improve soil fertility, increase crop yield, improve the quality of agricultural products, and achieve high-yield, high-efficiency, high-quality, and ecologically safe conditions. The purpose of application is of great significance to maintaining the sustainable development of agriculture.

The organic-inorganic compound fertilizer has a remarkable fertilizer effect, but its development is slow. The reasons are: first, due to the different organic material resources in different places, the treatment process is complicated, and the pre-treatment cost is high. In the production process, due to the strong water absorption and looseness of organic materials, it has a great influence on the granulation and drying process, it is difficult to granulate, it is difficult to dry, and the production cost is relatively high. Second, at present, some compound fertilizer enterprises do not have organic material fermentation devices to produce organic-inorganic compound fertilizers. Most of the organic raw materials are directly used raw lignite powder with high organic content without ammonia treatment, which affects the fertilizer efficiency of organic-inorganic compound fertilizers. Therefore, in order to speed up the promotion and application of organic-inorganic compound fertilizers, the following three links must be grasped in actual production:

1.Pretreatment of organic materials.

The pretreatment process usually refers to the organic fertilizer fermentation process. Fermentation and decomposing are the quality basis of organic fertilizers. The ideal conditions for fermentation include:

①Moisture. Maintaining proper water content is the primary condition for promoting microbial activity and compost fermentation. Generally, the maximum water holding capacity is about 60%. Excessive moisture will prolong the heating time, otherwise the heating will be fast, but the cooling will also be fast, and the rot will be incomplete. Only the proper moisture can keep the fermentation material continuously warm in the range of 50-65°C.

② ventilation. Maintaining proper air in the heap is conducive to the reproduction and activity of aerobic microorganisms and promotes the decomposition of organic matter. When composting at high temperature, attention should be paid to the appropriate amount of stacking and tightness. In the trough fermentation, try to add auxiliary materials according to the process requirements to facilitate ventilation.

③Maintain a neutral or slightly alkaline environment. A suitable PH environment can promote the reproduction and activity of microorganisms. Adjust pH, when material alkalinity is too large, can add H PO (phosphoric acid), KH PO (Potassium dihydrogen phosphate), FeCI , FeSO .7H O in an amount. If the material is acidic, add one of CaO (quick lime), NaOH (caustic soda) and K2HPO4 (dipotassium hydrogen phosphate) in an appropriate amount.

④ carbon to nitrogen ratio. The carbon-nitrogen ratio for the normal decomposition of organic matter by microorganisms is 25:1. And the carbon-nitrogen ratio of legume green manure is 15~25: 1, the weed is 25~45: 1, and the stalk of grass crops is 60~100: 1. Therefore, according to the type of compost material, an appropriate amount of nitrogen-containing substances should be added to adjust to reduce the carbon-nitrogen ratio and promote microbial activity.

The organic material fermentation process route is to mix wet manure with straw powder and fermented dry organic material, and reduce the moisture content of the mixed material from 80% to about 55%; if the fresh manure moisture is suitable for the fermentation process requirements, you can omit dry and wet The mixing process; using biological fermentation to exothermic heating and sterilization, evaporating water, reducing the moisture content to less than 30%, reducing the volume and achieving the requirements of harmlessness and resource utilization. The fermented organic materials do not need to be bagged out of the tank, but are generally piled and put into the warehouse for 7-15 days of aging treatment.

2.Granulation and drying adjustment.

The organic-inorganic compound fertilizer can be produced by the typical solid pellet method, and the technological process is basically similar to the chemical compound fertilizer process. The difference is that granulation requires two-stage granulation with drum and disc, and continuous two-stage drying is also required for drying, so that the moisture can meet the requirements of particle strength and non-caking. The production of organic-inorganic compound fertilizer requires the addition of 30% organic materials, and four factors that affect the production of organic materials must be fully considered:

①Moisture problem. Good fermentation bacteria, good fermentation device and reasonable fermentation cycle can reduce the moisture content of the fermented material to 25%, otherwise it needs to be pre-dried or concentrated in sunny days and used in batches. The high moisture content of the material not only increases the drying load of the production line, but also makes the formula with high urea content unable to be produced.

The organic-inorganic compound fertilizer needs to be thermally granulated. The granulated material is within a certain range, and the viscosity of the material is good. The comprehensive moisture of the new material formula entering the granulator cannot exceed 10%, and the moisture of the organic raw material is required to be less than 25%. The content should be high and the moisture content should be low.

② fineness problem. The finer the material, the higher the viscosity of the material and the higher the specific gravity of the material, both of which are conducive to granulation, making the particles round and bright. Organic materials have many coarse fibers and impurities, and there is currently no suitable high-humidity material fine powder machine. Enterprises generally perform pre-drying and then finely pulverize. The fineness ratio of organic materials used for granulation is 60% above 60 mesh, and 60-40 mesh can only account for 40%.

③ specific gravity problem. The specific gravity of organic materials before fermentation is generally 0.5, and the specific gravity of fermented rot is 0.7 after fine grinding. If the specific gravity of the granulated material is light, the movement trajectory required for granulation cannot be completed. In the production of organic-inorganic compound fertilizers, it is generally necessary to select raw materials with high organic matter and high nutrient content, and leave a certain formula space to adjust the specific gravity and viscosity of the materials.

④ stickiness problem. The organic-inorganic compound fertilizer formula needs to add about 30% organic materials to ensure that the organic matter content reaches the standard. Organic materials are generally non-viscous, fully fermented and decomposed and finely pulverized. Although the viscosity of organic materials can be improved, it still cannot meet the viscosity requirements required by the granulation method. Therefore, adding a certain amount of viscous granulation binder is necessary. indispensable. However, the national standard for organic-inorganic compound fertilizers has dual requirements for nutrients and organic matter, and the space for addition is limited, so the added viscous material must be small in amount and good in viscosity.

3.Requirements for ingredients and recipes.

Due to its inherent characteristics, organic-inorganic compound fertilizers have a wide variety of complex organic materials. The factory needs to choose according to local organic resources, and must be fully fermented and decomposed. Inorganic nitrogen, phosphorus and potassium must be selected from urea, diammonium phosphate, monoammonium phosphate, potassium chloride and potassium sulfate with high nutrient content. Chemical fertilizers are mostly inorganic salts. If microbial inoculants are added to organic-inorganic compound fertilizers, the amount of chemical fertilizers added should not be too high, otherwise the activity of microorganisms will be inhibited. The formula design can refer to the existing chemical compound fertilizer nutrient distribution ratio, but it cannot be copied, because the nitrogen, phosphorus and potassium ratio in the organic-inorganic compound fertilizer has its particularity. The main performance is that the nitrogen supply process of organic-inorganic compound fertilizer has less fluctuation and is relatively stable, and will not fluctuate greatly. The intensity and durability of fertilizer supply are more coordinated, and are more suitable for the fertilizer needs of crops in various periods of growth. Phosphorus has high availability, is not easily fixed, and potassium is not easily lost. Therefore, the proportion of nitrogen in the formula can be appropriately high without being too high, and the proportion of phosphate fertilizer can be appropriately low without insufficient phosphorus supply.

Organic-inorganic compound fertilizers can effectively prevent the volatilization of nitrogen, the fixation of phosphorus, and the loss of potassium because organic matter fully absorbs inorganic nutrients in the production process. The fertilizer effect is better than that of chemical compound fertilizers with the same content. Base fertilizer, top dressing or seed fertilizer. Seed fertilizer should not be in direct contact with seeds; as base fertilizer, the application rate is generally 50 ~ 150kg per mu; as top-dressing fertilizer, the amount of nutrient input in the current season should be referred to, and the application amount can be appropriately reduced compared with the base fertilizer; the fertilization period can be appropriately advanced to prevent greed and late maturity .