The so-called slow and controlled release fertilizer refers to the nutrient initially released slowly through various regulatory mechanisms to extend the effective period of the crop's effective nutrient absorption and utilization, so that the nutrient is set according to the release rate and release period of slow or controlled release fertilizer. This fertilizer has the advantages of increasing the utilization of chemical fertilizers, reducing the amount of use and the number of fertilizers, reducing production costs, reducing environmental pollution, and improving the quality of crop products. The outstanding feature is that the release rate and release period are organically combined with the crop growth rules, thereby making the fertilizer The effective utilization of nutrients increased by more than 30%.
Controlled-release fertilizers are coated with a special membrane in the outer layer of traditional fertilizers. According to the crop nutrient requirements, controlled release of nutrient release rate and release amount, the nutrient release curve is consistent with the crop demand. The outstanding characteristic of this fertilizer is to supply effective nutrients synchronously according to the crop growth curve, so that the effective utilization of fertilizer nutrients is greatly improved. Under the premise of ensuring crop growth, the fertilizer efficiency utilization rate can be increased by more than 30% compared with the same concentration of fertilizer. , can greatly reduce the amount of traditional fertilizer. Because slow-release fertilizers have the advantages of reducing the amount of fertilizers, saving fertilizer production raw materials (coal, electricity, natural gas), increasing fertilizer utilization, and reducing environmental pollution, they are called “21st-century high-tech environmentally-friendly fertilizers†and become a fertilizer industry. The direction of development.
The American Crop Nutrition Association's (AAPFCO) definition of sustained-release fertilizers and controlled-release fertilizers is that the nutrient forms contained in fertilizers can delay the absorption and utilization of crops after fertilization, and the nutrients contained in them have a longer fertilizer effect than quick-acting fertilizers.
However, in the narrow sense, there are different definitions for slow-release fertilizers and controlled-release fertilizers. Slow release fertilizers (SRFs), also known as long-acting fertilizers, mainly refer to fertilizers that are applied to the soil and converted into effective nutrients in plants that are slower than ordinary fertilizers. The release rate, mode, and duration cannot be well controlled, and is greatly affected by fertilization methods and environmental conditions. The advanced form of slow-release fertilizers is Controlled Availability Fertilizers (CAFS), which refers to pre-setting the release pattern of fertilizers in the crop growing season through various mechanisms and measures, so that the nutrient release rules are basically synchronized with the absorption of crop nutrients, and thus A type of fertilizer that achieves the purpose of improving fertilizer efficiency.
In recent years, controlled release fertilizers have been described as fertilizers that have a known release rate, manner, and duration and can be controlled during the use of the fertilizer. The European Committee for Standardization (CEN) has combined studies on the slow release rate and controlled release rate of sustained release and controlled release fertilizers and the release time, and proposes that they should be available as sustained release and controlled release fertilizers. A specific criterion is that the release rate of nutrients in a fertilizer at 25°C within 24 hours (ie, the chemical form of the fertilizer is converted into an effective plant available form) does not exceed 15%; 2 The nutrient release rate within 28 days Not more than 75%; 3 Within a specified time, the nutrient release rate is not less than 75%; 4 The nutrient release curve of the special controlled-release fertilizer is consistent with the nutrient absorption curve of the corresponding crop.
First, the classification of controlled-release fertilizer
1. Physically controlled release fertilizer
The physical slow and controlled release fertilizers are processed through simple physical processes to make the fertilizers have controllability.
Most of the physical slow-release fertilizers are coated fertilizers. Generally, one or more layers of inert substances are sprayed on the surface of the fertilizer particles through some means such as heating, spraying, drying, etc., to form a dense, low-permeability membrane, which can control water into people. The rate at which the nutrient core and the nutrient solution diffuse from the inside of the membrane to the outside, thereby delaying the release of nutrients from the fertilizer.
The better the water resistance of the membrane, the slower the dissolution of the fertilizer. The nutrient release process begins with water permeating through the membrane. The water vapor condenses on the solid fertilizer core and dissolves some of the fertilizer core, causing an internal pressure build-up. If the internal pressure exceeds the resistance of the membrane, the capsule ruptures, and the particulate nutrients are rapidly released. This release process is called the Failure Mechanism; if the membrane can withstand the internal pressure, nutrients in the fertilizer will diffuse. The release, the driving force is the concentration gradient inside and outside the membrane, this release process is called the "diffusion mechanism." Whether these two processes occur or not depends critically on the mechanical conditions, thickness, quality of the membrane, and the radius and shape of the coated particles. The diffusion of nutrients within the envelope can be altered by controlling the nature of the envelope.
Common coating materials are mainly divided into organic and inorganic two kinds of inorganic compounds as the wrapping material of sulfur, metal oxides and metal salts, inorganic chemical fertilizers. As the coating material, organic materials include paraffin wax, olefin polymer or copolymer round, unsaturated oil, natural rubber, and the like.
According to the current studies on slow-release nitrogen fertilizers, the manufacturing process of coated slow- and slow-release fertilizers does not involve the chemical reaction of chemical fertilizers. The release rate of fertilizer nutrients is controlled by adjusting the composition and thickness of the coating materials. This type of fertilizer is affected by the outside world. The influence of environmental factors is small, and its release characteristics can be flexibly adjusted. The manufacturing process method is simple and easy, and it has great technical and economic advantages.
2. Chemical controlled release fertilizer
The release mechanism of chemical nutrient slow-release nitrogen fertilizers is relatively complex, and the comprehensive summary includes two types: one is that chemical additives do not combine with the target fertilizer, and the other is that chemical additives and fertilizers combine to form new substances.
In the case where the chemical additive does not combine with the target fertilizer, two forms are included, one of which is adding a soluble substance in the target fertilizer. Taking slow-release urea as an example, inorganic salts, organic substances, etc. containing copper, zinc and manganese compounds and other trace elements required by plants are added to urea. These substances can slow down the dissolution of urea and slow the release of nutrients. Another form is to add nutrient release inhibiting substances to the target fertilizer, such as adding urease activity inhibitor and nitration inhibitor to urea. The addition of urease inhibitors can reduce the activity of urease, thereby slowing the rate of decomposition of urea, ie slowing down the amination process. The addition of nitrification inhibitors can selectively inhibit the activity of nitrite bacteria, nitrate bacteria, and denitrifying bacteria, thereby reducing the nitrification and denitrification of nitrogenous fertilizers. The main nitrification inhibitors include halogenated phenols, nitroanilinium, and phenylammonium halides. Thiourea, methionine, pyridine, pyrimidine, thiourea, dicyandiamide (DCD), etc.
The other type is chemical additives that combine with target fertilizers to form new substances, such as the condensation of formaldehyde and urea under certain conditions to produce urea formaldehyde; acetaldehyde and urea form a cyclic structure material in an acidic environment; isobutyraldehyde reacts with urea to produce Such as isobutylene diurea (IBDU), the nutrient release mechanism of this kind of slow and controlled release nitrogen fertilizer is that the compound is decomposed under the influence of external environmental conditions (such as biological action, soil pH, moisture content, temperature, etc.) The chemical bond with urea breaks down, regenerating urea and a specific compound, which then releases the nitrogen needed for plant growth. The release rate depends on the nature of the composition bond, stereochemical structure, hydrophobicity, ease of degradation, fertilizer shape, ratio between surface area and volume, and the role of microorganisms.
Second, the type of controlled-release fertilizer
The slow-release fertilizer in the broad sense includes two types of slow-release fertilizer and controlled-release fertilizer.
1. Slow release fertilizers: The release rate of nutrients in fertilizers is slowed by chemical and biological factors. Mainly slow-acting nitrogen fertilizers, also known as long-acting nitrogen fertilizers, generally have very low solubility in water. After being applied to the soil, under the action of chemical and biological factors, the fertilizer gradually decomposes and the nitrogen is slowly released, which satisfies the demand of nitrogen for the whole growth period of the crop.
2. Controlled-release fertilizers: The water-soluble fertilizers are wrapped in the membrane to slowly release nutrients through the external coating method. When the coated fertilizer particles come into contact with moist soil, moisture in the soil penetrates through the envelope and penetrates into the interior, dissolving some of the fertilizer.
The rate of fertilizer release depends on the temperature of the soil and the thickness of the membrane. The higher the temperature, the faster the rate of dissolution of the fertilizer and the speed through the membrane; the thinner the membrane, the faster the penetration.
According to different film-forming substances, it can be divided into non-organic coated fertilizers, organic polymer coated fertilizers, and thermal resin coated fertilizers. Among them, organic polymer coated fertilizers are currently the most studied and most effective controlled-release fertilizers.
Both slow-release fertilizers and controlled-release fertilizers are fertilizers that have a longer fertilizer effect than quick-release fertilizers. In this sense, there is no strict difference between slow-release fertilizers and controlled-release fertilizers. However, from the perspective of controlling the mechanism and effect of nutrient release rate, slow-release fertilizer and controlled-release fertilizer are different.
Slow release fertilizers are affected by many external factors such as soil pH value, microbial activity, soil moisture content, soil type, and irrigation water volume at the time of release. The release of fertilizer is not uniform, and the nutrient release rate and the nutritional requirements of the crop may not be completely synchronized. Most of the monomer fertilizers are mainly nitrogen fertilizers.
Controlled-release fertilizers are mostly N-P-K compound fertilizers or total nutrient fertilizers supplemented with trace elements. When applied to soil, the release rate is only affected by the soil temperature. However, soil temperature has a great influence on the growth rate of plants. In a relatively large temperature range, the soil temperature increases, the release rate of controlled-release fertilizers is accelerated, and the growth rate of plants is accelerated, and the demand for fertilizers also increases.
Therefore, the rate of release of nutrients from controlled-release fertilizers is in line with the plant's demand for nutrients, which can meet the demand for nutrients at different growth stages of crops.
Third, the advantages of controlled-release fertilizer
Compared with ordinary fertilizers, slow-release fertilizers have the following advantages:
1. Improve fertilizer utilization and reduce fertilizer use. Since the slow-release fertilizer has a sustained-release effect, it can reduce the gaseous state and the leaching loss of the fertilizer, thereby increasing the utilization efficiency of the fertilizer. China's first company to convert slow-controlled release fertilizer production technology into productivity, the Shandong Kim Jungda Group has passed a large number of experimental data shows that: slow-release fertilizer can reduce fertilizer utilization from the original 35%, nitrogen loss rate was significantly reduced, Nitrogen fertilizer can be saved by 30%-50%.
2, reduce the number of fertilization and save labor. Due to the lack of labor in the countryside or due to lack of water, water supply is not timely, and other reasons, the fertilization of crops has become increasingly simplified, and one-time fertilization of crops has become quite common. The one-off fertilizers currently sold on the market are basically quick-acting high-nitrogen compound fertilizers, and there is a risk of prolonged seedlings or later defertilization. The controlled-release fertilizer can be scheduled to design fertilizer release mode in the crop growing season, so that the nutrient release law of fertilizer and crop nutrient absorption is consistent, one-time fertilization to meet the needs of the entire growing season of crops.
Slow-release fertilizers can also be used for no-tillage and soilless cultivation. Seeds are good. When the standards are met, seeds and fertilizers can be planted in one go and irrigation can be done. It is very convenient.
Now many soilless cultivation irrigation nutrient solution. There are also a lot of problems, sometimes guilty of illness, and sometimes the nutritional solution is not well equipped, the seedling growth is not good, and the use of controlled-release fertilizers will solve this problem.
3. It can reduce crop diseases and improve the quality of agricultural products. Crop diseases and product quality are related to the amount of nitrogen fertilizer. Slow and controlled release fertilizers can prevent crops from excessively absorbing nitrogen and thus play a role in inhibiting diseases and improving quality.
IV. Advantages of Slow Controlled Release Fertilizer
1. Slow-release fertilizer refers to a new type of fertilizer that can delay or control the release rate of nutrients. Relative to quick-effect fertilizer, there are some advantages:
(1) The solubility in water is small, nutrient elements are released slowly in the soil, and the loss of nutrients is reduced.
(2) Fertilizer efficiency is long-term and stable, and energy sources continuously supply the nutrient demand of plants throughout the production period.
(3) Due to the slow release of fertilizers, a large number of applications will not cause excessive soil salinity and “burn seedlingsâ€.
(4) Reduce the amount and frequency of fertilization and save costs.
2. Controlled-release fertilizer is one of the key fertilizers promoted by the Ministry of Agriculture and the third revolution in agricultural production.
Coated controlled-release fertilizers control the nutrient release rate of dozens of materials with different thicknesses and different materials, so that the nutrient release rate of fertilizers is consistent with the required fertilizer rate of the crop growth cycle. Compared with conventional fertilizers, it has the following characteristics:
(1) High utilization rate of fertilizer efficiency: nutrients of conventional fertilizers are evaporated through the air, penetrated underground, and lost surface water. Less than 30% of the crop is actually used. The control of Dr. Nong's coated controlled-release fertilizer and the control of outer coating materials prevented the above-mentioned losses from being more than 80%.
(2) The effect of increasing production is obvious: through the control of nutrient release by coating, the supply of nutrients to crops is stable and regular, and crops are prevented from defertilization and leggy, and the rate of increase in production is mostly above 200 pounds/mu.
(3) Eliminating time and labor and liberating the labor force: Using Dr. Agronomy Controlled Release Fertilizer, most crops can realize one-season crops with only one application of fertilizer and no fertilizer for life, saving time and effort and reducing waste.
(4) Bactericidal and insect repellent effects are obvious: The controlled-release fertilizer is made of polysulfide compound, which can sterilize and insecticide. Each bag of fertilizer can send more than ten kilos of fungicide.
(5) Long-term use of improved soil: After the release of nutrients, the empty shells will be able to store water, protect the soil, and function as a ventilator and a fertilizer to loosen long-term compacted soil.
(6) Sulphur supplementation: Sulfur is also an indispensable element in crop growth. After releasing the controlled release fertilizer, Dr. Nong’s controlled release fertilizer can be directly involved in nutrient release and be absorbed by crops.
V. Suggestions on Promoting Slow Controlled Release Fertilizers
The promotion and application of controlled-release fertilizer is a good thing to benefit the country and the people, meets the requirement of “accelerating the building of a resource-saving and environment-friendly societyâ€, and promotes the harmonious and friendly development of agriculture and resources, agriculture and the environment, and promotes food production. Safe and clean production and increasing farmers' income are all important. However, in the face of the actual situation and existing problems of agriculture and farmers in our country, there is no widespread concern and participation of the whole society. It is difficult to accomplish in one aspect alone, and it is necessary to mobilize the forces of various sectors of society to participate in joint actions. , for this proposal:
1. Intensify publicity and education to raise people's awareness of the importance and urgency of developing modern agriculture. (1) Widely publicize and promote the use of slow-release fertilizers, the significance of building a conservation-oriented society and the sustainable development of agriculture, and raising people's awareness of the importance of scientific fertilization. (2) Relevant government departments, agriculture-related departments at all levels, and agricultural extension departments in particular should put promotion and application of slow-release fertilizers on the important agenda and take them seriously. All personnel, especially technical personnel, must widely disseminate and guide farmers. . (3) Giving full play to the role of farmer cooperatives, associations and other civil society organizations, establishing a knowledge system for fertilizer consumption, and jointly organizing training courses and broadcasting science and education with relevant departments to help farmers improve scientific fertilization and change irrational fertilizer habits. . (4) Production enterprises can extensively carry out trials of controlled-release fertilizers and demonstration farms in accordance with the characteristics that farmers believe. By demonstrating the fields and areas, farmers can feel the effects of controlled-release fertilizers and gradually expand the area for promotion and application.
2. It is recommended that the national and relevant departments can give support to the promotion and application of controlled-release fertilizers in terms of policies, funds, etc., in order to increase the enthusiasm of scientific research units, enterprises for promotion and application, and farmers' application. (1) According to the spirit of “increasing investment in modern agriculture†put forward by the Central Government, agricultural institutions, agricultural technology promotion departments and enterprises that apply R&D, production, promotion and application of controlled-release fertilizers are given preferential policies and funds. (2) Research institutes and enterprises that actively carry out research on the application of slow- and controlled-release fertilizers and carry out experiments on controlled-release fertilizers and demonstration fields may provide certain support in terms of credit and taxation. Support the backbone of the organization's technology, engage in research, experiment, and demonstration work on the application of slow-release fertilizers, and accelerate the promotion and application of slow-release fertilizers. (3) Actively encourage and guide farmers to use slow-release fertilizers. They can learn from foreign experience. Farmers applying slow-release fertilizers will be given a certain percentage of subsidies on the basis of maintaining the original subsidies.
3. It is recommended to combine the use of slow-release fertilizers with soil testing and formula fertilization to achieve effective combination of high-tech and low-cost and complementary advantages. At present, soil testing and formula fertilization has risen from a technical measure to a national policy. The behavior from one department to the state behavior has been very popular among farmers. According to the test results of soil testing and the law of fertilizer requirements of the crops and soil fertility, BB fertilizers mixed with slow-release fertilizers and normal fertilizers are developed, which can not only balance the effects of fertilization but also provide controlled release. The unique slow and controlled release technology of fertilizer can realize “one crop of one-time fertilizer†to meet the demand for nutrients at each stage of the crop growth period. At the same time, not only the waste of resources and environmental pollution are avoided, but also the production costs and sales prices of fertilizers are reduced, the labor intensity of farmers is also reduced, and the income of farmers is increased. Farmers are more receptive and can play a multiplier role. In the slow and controlled release fertilizer industrialization and large-scale application.
2L-size Carrot,2L-size Fresh Carrot,Fresh Carrot Size 2L,2L-size Red Color Carrot
Yirun Agricultural Cooperative , https://www.yiruncn.com