More and more people enjoy salmon, a good Vacuum bag is very important. MST Packaging is a flexible packaging manufacture more than 20 years in China. Our packaging is good design and good quality. Vacuum Packaging Bag is one kind of packaging bag, the material we usuallly use PET12/NY12/PE60. It can be not only printing colorful but(Within 10C) puncturing resistance, and with good tightness. The MOQ for this kind bag is 10000pcs per design. The normal bag styles in Vacuum packaging we have 3 side seal bag, side gusset bag and flat bottom bag. The size and printing all can be customized. The printing is grave printing(Within 10C) which looks lively. Vacuum Packaging bag is widely used. Vacuum Packaging Bag,Vacuum Stand Up Bag,Vacuum Pouch With Zipper,Vacuum Flat Bottom Bag MST Packaging Co., Ltd. , https://www.mstpack.com
1.2 Overview of the current use of straw in China
Analysis: Current status, problems and development prospects of straw fertilizer
[ China Agricultural Machinery Industry News ] Straw is a general term for the stems and leaves (ears) of mature crops. Usually refers to the remainder of wheat, rice (Oryza sativa L.), corn (Zea may L.) and other crops after harvesting seeds. More than half of the photosynthesis products of crops are found in straw, which is also rich in nitrogen, phosphorus, potassium, calcium, magnesium and organic matter. It is a multi-purpose renewable biological resource. Straw fertilizer production is a certain condition to control, through a certain technical means, in the factory to achieve decomposition and stability of straw rot decomposition, and finally convert it into a production method of commercial fertilizer, its products generally mainly include refined organic fertilizer and organic - Two products of inorganic compound fertilizer. Organic fertilizers or organic-inorganic compound fertilizer products using agricultural organic raw materials such as straw and straw for agricultural production have important significance and remarkable effects in improving soil properties, improving agricultural product quality and increasing agricultural product yield. In recent years, a large amount of chemical fertilizer has made the physical and chemical properties of the soil worse, and it has affected the quality of crops and the sustainability of yield. The products produced by straw fertilization have increased soil organic matter, nitrogen, phosphorus, potassium and various trace elements. The content of the soil, reducing the bulk density of the soil and increasing the total porosity, and maintaining the continuous increase of crop yield are effective methods to solve the above problems.
Li Guoxue et al. used organic fertilizer and organic-inorganic compound fertilizer produced by straw compost to cultivate the cabbage, and the results showed that they could increase the soil organic matter, total nitrogen, available phosphorus and available potassium. In addition, the gradual release of nutrients from organic fertilizers and organic-inorganic compound fertilizers reduces leaching losses and increases utilization. The use of agricultural organic raw materials such as straw for fertilizer production can also improve the soil environment, especially the composition and quantity of various microorganisms in the soil. It is well known that soil microorganisms (bacteria, fungi and actinomycetes) transform and utilize various elements in the soil through their own physiological functions, so that they are absorbed and utilized by plants. Therefore, the type and quantity of soil microorganisms are also judged by soil fertility. One of the indicators. The content of organic matter in soil and its composition are the main factors affecting the quantity and variety of microorganisms. Applying proper amount of organic fertilizer and organic-inorganic compound fertilizer in agricultural production can effectively increase the number and variety of microorganisms and increase the utilization rate of fertilizer. The quality and yield of crop products will also increase due to the application of organic fertilizer or organic-inorganic compound fertilizer produced by straw fertilization. Ji Yunmei and Ren Xuqin examined the effects of organic-inorganic compound fertilizer on the quality and yield of Chinese cabbage. The result was that the nitrate content was reduced by 11.5% and the soluble sugar content was increased by 42.1%, and the yield increased by 168%. Liu Jie et al studied The effect of organic-inorganic compound fertilizer on soybean quality and yield showed that the crude protein increased by 1.04% compared with conventional fertilization, the crude fat decreased by 0.2%, and the yield increased by 11.1%. Gu Jie et al [4] used straw and livestock manure The application test of organic-inorganic compound fertilizer for organic raw materials in winter wheat production also showed that it has a good yield increasing effect, and its yield increase ranged from 17.4% to 18.7%, and the water utilization rate also increased by 13.8%~15.4%. .
Analysis: Current status, problems and development prospects of straw fertilizerization/Photos from Baidu invasion
1 Overview of China's straw resources and their utilization
1.1 China's straw resources
China is a big agricultural country and a big country with straw resources. Since the end of the 20th century, under the influence of agricultural policies, China's grain output has increased year by year, and straw production has also increased. By 2007, the total amount of straw in China had reached 747 million tons, accounting for 20% to 30% of the total global straw, and more than 50% were mainly distributed in Sichuan, Henan, Shandong, Hebei, Jiangsu, Hunan. Hubei, Zhejiang and other provinces. China's straw production accounts for more than 85% of total grain production in rice, wheat and corn crops (2007). Straw is a versatile and renewable biological resource that is rich in nitrogen, phosphorus, potassium, calcium, magnesium and silicon in addition to organic substances such as cellulose, hemicellulose, lignin, protein, fat and ash. Equal mineral elements [6]. The statistics of Zhang Fudao et al. show that the straw of leguminous crops contains more nitrogen, and the straw of gramineous crops is richer in potassium. The nutrients provided by crop straw account for about 13%-19% of the total nutrients of organic manure in China, which is an important organic for agricultural production. Fertilizer source.
Tables 2 and 3 provide the minerals and organic matter types and contents of several crops [8]. It is estimated that the nitrogen, phosphorus and potassium nutrient contents of 600 million tons of straw are equivalent to 4 million tons of urea, 7 million tons of superphosphate and 7 million tons of potassium sulfate. In 2005, the application rates of nitrogen, phosphate and potassium in China were not enough. 22,233,000 tons, 7.438 million tons and 4.895 million tons. It can be seen from the above that China's straw resources are extremely rich, and as long as they are used rationally, they can turn waste into treasure.
Today, most of China's straw has been developed and utilized in different ways. These utilization methods mainly include straw returning, straw energy, straw feed, and straw cultivation edible fungi. Straw returning mainly includes mechanized crushing and returning, covering and returning to the field. It occupies an important position in the utilization of straw fertilizer, but the utilization of mechanized direct comminution and returning to the field is equivalent to about 15% of the total amount of straw, and the area of ​​straw returning also accounts for about 15% of the total sown area [ 9]. The study confirmed that adhering to the straw returning to the field not only has obvious effect of increasing yield in the fertilization stage, but also has obvious aftereffect and has a continuous increase in yield.
Straw energy utilization technology mainly includes straw solidification molding fuel, straw power generation, straw biogas (biogasification), straw pyrolysis and gasification straw retorting, etc. However, there are still many problems in China in terms of equipment production and utilization efficiency. .
Straw feedstock utilization is the use of straw as livestock feed. It can be said that it is one of the early utilization methods of straw. Modern methods for producing animal feed using straw mainly include direct feeding, straw ammoniation, straw silage, and fermentation to produce single-cell protein feed. A few. Straw feedstock is also one of the important aspects of the effective utilization of straw in the context of the great development of China's aquaculture industry.
Straw cultivation edible fungi refers to the use of straw as a culture material to produce edible fungi. With the improvement of utilization technology, there are more than 20 varieties currently produced, including various kinds of oyster mushrooms, mushrooms, fungus and ganoderma lucidum. In addition, some straw is also used in the production of industrial products such as alcohol, board and paper. Even so, a considerable part of the straw has not been rationally utilized as an important factor in environmental pollution. Fertilizer production is one of the more promising ways of using straw. The following sections will focus on its current situation, existing problems and development prospects.
2 Straw fertilizer production status
Crop straw itself has unbalanced nutrients, low content and is not easy to be decomposed. It is often necessary to cooperate with livestock manure produced by farms, domestic garbage, sludge produced by sewage treatment plants, etc. to jointly produce fertilizers, and some special ones need to be added. Bacterial agent. The amount of straw should be adjusted according to the nutrient content and water content of other materials. Adding the pulverized straw can effectively improve the carbon-nitrogen ratio and water content of the fermentation material, thereby facilitating the inoculation of the microbial agent. In addition, some studies have attempted to directly compost the straw, but industrial production has not been reported.
2.1 China's organic fertilizer production statistics show that in the 1950s, China's fertilizer input was 99%
It was organic fertilizer, which shrank to 2/3 of the total fertilization in the 1970s, and less than a quarter in the 1990s. In recent years, with the development of demand for green food, organic food, and the problems caused by long-term non-application and low application of organic fertilizer, people have begun to pay attention to the investment in organic fertilizer, which has promoted the development of China's organic fertilizer industry. A variety of production processes and products have been developed, but they can be roughly classified into two categories: refined organic fertilizers and organic-inorganic compound fertilizers.
Refined organic fertilizer is generally processed by the process of decomposing, fermenting, sterilizing, mixing and pulverizing crop straw or poultry manure. The raw materials are mostly agricultural waste, and the content of organic components of the main functional components is more than 50%. Mainly used in the production of organic foods and green foods; organic-inorganic compound fertilizers refer to the fertilizers produced by adding a certain amount of organic matter in the process of producing inorganic compound fertilizers, which contain both large amounts of elements and organic matter.
The industry has developed rapidly since the beginning of the 21st century. The number of refined organic fertilizers and organic-inorganic compound fertilizer producers in the country has soared from 156 and 294 to 687 and 615 respectively, equivalent to a net increase of more than 3 times and 1 More than double, while the output has also increased by about 2 times. However, organic fertilizer enterprises are characterized by regional distribution and generally small scale: organic fertilizer production enterprises are mainly distributed in areas rich in organic fertilizer raw materials (such as Shandong and Hebei) and economically developed areas (such as Guangdong and Jiangsu), and more than 50% concentrated. Distributed in Shandong, Hebei, Liaoning, Guangdong and Jiangsu provinces; China's organic fertilizer production enterprises with an annual output of less than 100,000 tons of less than 10, an annual output of 50,000 to 100,000 tons of the total number of insufficient 10%, with an annual output More than half of the 10,000 tons or less.
2.2 Process of straw organic fertilizer production
The organic fertilizer production process of straw varies according to the final product. For refined organic fertilizer and organic-inorganic compound fertilizer, the process of refining organic fertilizer is part of the process of organic-inorganic compound fertilizer. The production process of refined organic fertilizer is roughly the same.
2.2.1 Production process of refined organic fertilizer
The mixed materials of straw and livestock manure are composted to form refined organic fertilizer products. The production process mainly includes raw material pulverization and mixing, primary fermentation, aging (secondary fermentation), pulverization and screening and packaging. Refined organic fertilizer is now implemented in the industry standard NY 525-2002.
The production methods of refined organic fertilizer mainly include several types of fermented compost, trough compost and reactor compost. They have their own advantages and disadvantages and need to be selected according to the local conditions of the enterprise, but their production processes are basically the same. (see picture 1). Straw is generally not directly used as a raw material for rapid composting, but is first pulverized. The previous experimental research and practice results show that straw smashing to about 1 cm is suitable for composting. The smashed straw and other materials such as livestock manure are mixed. The main purpose is to adjust the carbon-nitrogen ratio (25~30) of the raw material: 1 and the water content of about 60%, so that it is suitable for rapid propagation of microorganisms in the inoculant. Play a role. According to estimates, the ratio of pig manure and wheat straw powder is about 10:3, the ratio of cow dung and wheat straw powder is about 3:2, and the ratio of distiller's grains to wheat straw powder is 2:1 (the water content needs to be adjusted). However, the proportion of materials used in production needs to be adjusted according to the actual conditions of the materials. One fermentation (about 10 days) is the key to the whole process. The success or failure of the product directly determines the quality of the product. Therefore, it is necessary to monitor the temperature, moisture content and aeration of the material in real time in the process. Effectively control the composting process and product quality, this process usually needs to turn over the pile in time, the number of times is about 4~5 times. In the step of turning over the pile, it is necessary to master the principle of “time to non-isothermal, temperature to unequal timeâ€, that is, even if the temperature does not reach the limit of 65 ° C, it should be carried out in time, or as long as the temperature reaches 65 ° C will be turned over even if the time does not reach the next day.
The aging process (which lasts about 4 to 5 weeks) is mainly to further stabilize the material of one fermentation, during which vent holes need to be inserted to meet the oxygen requirements of the microorganisms. After the aging, the materials are separated from the unqualified products by sieving and sieving. The former is packaged and sold as the return material and recycled to a fermentation stage for recycling. When the organic fertilizer is produced by rapid composting, the materials generally undergo three stages of heating, high temperature and cooling, and the measures taken in each step of the above process are to meet the requirements of different stages of composting.
The warming phase is roughly a period of time (about 2 to 3 days) before the temperature of the mixture starts to stack up to 45 ° C in a fermentation, during which the mesophilic microorganisms (mainly bacteria) dominate and make it easy to decompose. Substances such as starch rapidly decompose and release a large amount of heat to raise the temperature of the stack. In order to rapidly increase the number of microorganisms in the heap, it is often necessary to add a microbial agent specially developed for compost production to the mixture.
The high temperature stage is mainly the time when the temperature of the stack rises to 45 ° C and ends at the end of one fermentation (about 1 week). In this stage, thermophilic microorganisms (mainly fungi and actinomycetes) dominate, and their aerobic respiration The action causes substances such as hemicellulose and cellulose to be strongly decomposed and release a large amount of heat. In this stage, it is necessary to turn over the pile in time (according to the principle of “time to non-isothermal, warm to unequalâ€) to adjust the ventilation volume of the stack, the temperature is 50~6 5 °C (good 5 5 °C), but not The temperature of the heap is increased to 70 ° C because the physiological activity of most microorganisms is inhibited or even killed at this temperature. In fact, this stage is also the stage to effectively kill pathogenic micro-organisms and weed seeds, which is the key to the whole compost production process.
The cooling stage corresponds to the aging process in the production process (about 4 to 5 weeks), the temperature is reduced to below 50 °C, and the mesophilic microorganisms (mainly fungi) begin to dominate and decompose the lignin and other substances that are difficult to decompose. . At this stage, the microbial activity is not very high, the heat generation of the heap is reduced, the oxygen demand is decreased, and the organic matter tends to be stable. In order to maintain the oxygen required for microbial physiological activities, it is necessary to insert some vent holes into the pile.
2.2.2 Organic-inorganic compound fertilizer production process of straw Organic-inorganic compound fertilizer is not a simple mixture of organic fertilizer and inorganic fertilizer. It is more difficult to produce organic fertilizer or inorganic fertilizer than the single one. Or the granulation product is not easy to meet the national organic-inorganic compound fertilizer product standard (GB 18877-2002). The nature of organic fertilizer itself is the main reason for granulation. According to national standards, organic fertilizer accounts for not less than 30% of the total raw materials of compound fertilizer, and the difficulty of granulation will increase with the proportion of organic fertilizer. Increase.
As far as the existing process is concerned, the production process of the organic-inorganic compound fertilizer has two stages, one is the production stage of the organic fertilizer, and the other is the mixed granulation stage of the organic fertilizer and the inorganic fertilizer. The production stage of organic fertilizer is the same as that of refined organic fertilizer. The materials such as straw also need to be processed by high-temperature rapid composting to become finished organic fertilizer. The process of granulation stage mainly includes the mixing of organic fertilizer and inorganic fertilizer, granulation of mixed materials, The granulation screening, product packaging and other steps, in which the granulation stage of the mixture is the main point of distinguishing the existing organic-inorganic compound fertilizer production process, is also the focus of research.
According to the granulation process selected in the production, the organic fertilizer should be pre-treated before granulation. If the material requires fine materials, it needs to be pulverized and sieved. The process requires low water content and needs to be dried. Wait.
At present, the mature granulation process mainly includes the following: (1) Drum granulation: After the mixed materials are wetted by the binder in the drum, they are continuously bonded to each other as the drum rotates. The binders are water, urea, humic acid, etc., depending on the production needs. The main features of the process are: organic fertilizer can be directly granulated without pretreatment; the binder has a wide selection range and strong versatility; the granulation rate is low, but the appearance is good.
(2) Extrusion granulation: The organic fertilizer and the inorganic fertilizer are mixed in a certain ratio, and are pressed or crushed into granules by different granulators such as a roll granulator or a tooth granulator. Materials with fine texture and good adhesion are more suitable for the requirements of the process, and if necessary, the water content needs to be adjusted to facilitate granulation. The main features of the process are: the material generally needs pre-treatment; no drying is required, the process is reduced; the product has high water content; the particles are uniform, but easily broken; the production requires large power and the production equipment is easy to wear.
(3) Disc granulation: the dried and pulverized organic fertilizer is mixed with an appropriate amount of inorganic fertilizer into the disc, and is humidified by the humidifier spray and then bonded at the bottom of the disc by the force generated by the friction between the disc and the inner wall. Granulated, then dried again, sieved and bagged. The disc granulation process has now developed both continuous and batch types. The characteristics of the process are: organic fertilizer needs to be dried and pulverized first, the process is cumbersome; the content of organic fertilizer is adaptable; the particles can be automatically classified but the granulation rate is low, the appearance is poor; the production capacity is moderate.
(4) Spray granulation: organic fertilizer and inorganic fertilizer are mixed in a certain proportion and then put into the granulator to be lifted, and then sprayed with slurry such as molten urea, and gradually crystallized to reach the corresponding particle size in the process of drying and cooling. The characteristics of the process are: high temperature for granulation; high granulation rate, less material return; strong production capacity.
In addition to this, some new granulation processes such as extrusion and granulation have also been applied. The process flow is roughly as follows: material mixing→disc feeding→extrusion granulation→granule polishing shaping→drying, cooling and sieving→metering packaging. The process combines the advantages of extrusion granulation and drum granulation, and the product is good in granulation, strength and appearance. The granularity, strength and appearance of the product are related to the market competitiveness of the product. In general, products with uniform particles, suitable strength and good appearance are easily favored by the market.
3 problems in straw fertilizer production
Straw fertilization production is one of the important ways of comprehensive utilization of straw, especially in combination with livestock manure and fecal production, so that straw and livestock manure are effectively utilized. However, there are certain problems in the straw fertilizer production that need to be further solved in future production practices or research. These questions can be summarized as follows:
(1) Although the straw has a wide range of sources, due to its wide distribution and loose texture, the cost of collection, transportation, storage, crushing and fermentation is high, which is not conducive to cost control. The purchase price of various materials is about 200 yuan / m3 (fresh base), pig manure 100 yuan / m3 (fresh base), cow dung 50 yuan / m3 (fresh base), distiller's grains 160 yuan / m (3 dry basis) However, due to different geographical and economic developments, the prices of various materials are also different. In general, the price of organic fertilizer at the factory should be around 500 yuan / t to have a certain profit, while the organic and inorganic compound fertilizer should be above 1000 yuan / t. 2) The composition of the straw is unstable due to differences in crop varieties, fertilization amount, fertilization variety, harvesting period, air drying degree, and the type, nature and composition of livestock manure used.
(3) The conditions of one fermentation process in the process of straw fertilization are not easy to control, and the quality of the fermentation product is easily unqualified.
(4) Straw Fertilization In the production process of organic-inorganic compound fertilizer, the nature of organic fertilizer itself and the selected granulation process are different, so that the quality of organic-inorganic compound fertilizer is different, and there is not enough mature at present. The granulation process can take into account various problems in the production of the product.
(5) The research on straw fertilizer production is not comprehensive and in-depth, so that it has not yet formed a set of production standards and procedures, which is not conducive to the necessary production supervision of enterprises.
4 Prospects for straw fertilizer production
The organic fertilizer and organic-inorganic compound fertilizer produced by straw fertilization have the advantages unmatched by inorganic fertilizers, the changes in soil physical structure and chemical properties, the improvement of crop quality, the maintenance of soil fertility and the continuous increase of grain yield and income. It has been recognized by the world. Although there are various problems in the process of straw fertilizer production, with the development of science and technology, the improvement of people's environmental awareness, the government's further attention and the introduction of relevant support policies, it will become one of the Chinese fertilizer industry. It is an important force to provide an effective solution to solve the problem of too little organic fertilizer input in the field production and environmental problems caused by improper treatment of straw. In short, straw fertilizer production has huge market potential in China. In order to accelerate the development of straw fertilizer production of organic fertilizer or organic-inorganic compound fertilizer industry, it is recommended that the state introduce relevant incentive policies that are conducive to its development as soon as possible, such as introducing some relevant financial subsidy policies and increasing the manpower of relevant basic research. And financial resources, develop and modify standards and specifications that are more in line with actual production needs, and recommend relevant production companies to strengthen research and development in process and equipment, as well as cost control research.