Fertilizer is a type of substance that provides one or more essential nutrients for plants, improves soil properties, and increases soil fertility levels. One of the material bases of agricultural production. As early as the Western Zhou Dynasty, China has known that field weeds can promote the growth of millet after they rot. "Qi Min Yao Shu" introduces in detail the method of planting green manure and the method of rotating leguminous crops with gramineous crops. It also mentions the method of mixing crop stalks with cow dung and urine, trampling and composting to make fertilizer. .
What are the types and functions of common fertilizers?
Ammonium phosphate fertilizers
Phosphoric acid (including polyphosphoric acid) and ammonia are neutralized and processed Nitrogen and phosphorus compound fertilizer. This is the largest and most popular fertilizer in the fertilizer category. It is suitable for almost all soils and crops. It has a high concentration of active ingredients and is not prone to moisture absorption and caking. Ammonium phosphate can also be used as a flame retardant for fabrics and fibers, a culture medium in the fermentation industry, a food additive and a feed additive, an acidifier in the printing and dyeing industry, and a dry powder fire extinguishing agent ingredient for firefighting. The production process of ammonium phosphate fertilizer is a combination of the phosphate fertilizer production process and the ammonia processing process in nitrogen fertilizer production, which is economically reasonable.
In the 1920s, industrial production of ammonium phosphate began, but on a small scale. In the early 1960s, the production technology of wet phosphoric acid tended to be perfected. Ammonium phosphate had relatively cheap raw materials, and the production developed very rapidly, with the United States developing the fastest. In 1968, the production of ammonium phosphate fertilizers (measured as P2O5) in the United States was approximately half of the total phosphate fertilizer production, which increased to 74.1 in 1981.
Variety Ammonium phosphate fertilizer varieties can be divided into three categories (see table). ①Ammonium orthophosphate is the category with the largest output. The main varieties are diammonium phosphate, monoammonium phosphate and a mixture of the two. ②Ammonium polyphosphate is a mixture of ammonium orthophosphate and ammonium phosphate salts with different degrees of polymerization. Most of them are used to make fluid compound fertilizers. ③ Compound fertilizer prepared from ammonium phosphate and other nitrogen fertilizers.
Water Soluble Fertilizer with Large Elements
Water Soluble Fertilizer (WSF for short) is a multi-component compound fertilizer that can be completely soluble in water. It can quickly Dissolved in water, it is more easily absorbed by crops, and its absorption and utilization rate is relatively high. More importantly, it can be used in facility agriculture such as sprinkler and drip irrigation to achieve the integration of water and fertilizer, achieving the efficiency of saving water, fertilizer and labor. Generally speaking, water-soluble fertilizers can contain all the nutrients needed for crop growth, such as N, P, K, Ca, Mg, S and trace elements. In this way, people can design formulas based on the nutritional requirements of crop growth. Scientific formulas will not cause waste of fertilizers, making their fertilizer utilization rate almost 2-3 times that of conventional compound chemical fertilizers (in China, The fertilizer utilization rate of ordinary compound fertilizer is only 30-40) Secondly, water-soluble fertilizer is a quick-acting fertilizer, which allows growers to quickly see the effect and performance of the fertilizer, and adjust the fertilizer formula at any time according to the different growth conditions of the crops. Of course, the application method of water-soluble fertilizer is very simple. It can be applied along with the irrigation water, including sprinkler irrigation, drip irrigation, etc., which not only saves water, but also saves fertilizer, and also saves labor. This is in the face of rising labor costs. The benefits of using water-soluble fertilizers today are clear. Since the application method of water-soluble fertilizer is irrigation with water, the fertilization is extremely uniform, which also lays a solid foundation for increasing yield and quality. Water-soluble fertilizers generally have less impurities and low conductivity, and the concentration is very easy to adjust. Therefore, they are safe even for young seedlings, and there is no need to worry about adverse consequences such as seedling burning. At the same time, the author believes that according to the requirements of crops, large-element water-soluble fertilizers must have the following technical characteristics:
●The water-soluble chelated trace element composition added to the ingredients must avoid antagonistic effects with phosphorus.
●For crops, it has the characteristics of stress resistance and yield increase, which can significantly improve the photosynthesis of crops, improve the yield and quality of crops, increase sugar content, and enhance resistance to cold, drought, disease, and lodging. Anti-stress properties and extended shelf life.
● Adding high-potassium formula can quickly meet the potassium demand of fruits and grains when they are enlarging, increase the sweetness of fruits, improve fruit coloring, and extend storage time.
Medium element fertilizer
Also known as secondary macro element fertilizer, it contains one or more compounds of the crop nutrient elements calcium, magnesium and sulfur, and the content needs to be marked. A type of chemical fertilizer. Minor constants are compared to the scale of production and application of the major constants nitrogen, phosphorus, and potassium. China calls it medium-element fertilizer. In addition to providing crop nutrients, this type of fertilizer can also adjust the physical properties of the soil and promote agricultural production. The production of medium-element fertilizers has not been paid much attention by people for a long time. The reason is that some commonly used fertilizer varieties, especially low-concentration fertilizer varieties, also contain calcium, magnesium or sulfur elements. Sulfur dioxide in the atmosphere enters the soil through rainwater and is also one of the sources of sulfur elements. In the past 30 years, high-concentration fertilizers have gradually replaced low-concentration fertilizers in the chemical fertilizer variety structure, which has reduced the calcium, magnesium and sulfur elements brought into the soil. Some soils have experienced a shortage of medium nutrients, especially a shortage of sulfur elements. As a result, the production and use of medium-element fertilizers have received attention. Calcium- and magnesium-containing fertilizers: limestone powder, dolomite powder, hydrated lime, shell powder and other industrial wastes containing calcium and magnesium are widely used as soil conditioners and provide calcium and magnesium nutrients. Its soil conditioning functions are: ①Improve the effectiveness of phosphorus fertilizer in the soil. In soils containing high amounts of iron and aluminum oxides, the effectiveness of phosphate fertilizers is reduced due to the reaction of phosphates with iron and aluminum compounds. Applying calcium and magnesium conditioners to maintain soil pH at 6 to 7 can slow down the above reaction. ② It is conducive to the reaction of converting ammonium nitrogen into nitrate nitrogen in the soil. Most nitrifying bacteria require calcium. ③Promote the process of biological nitrogen fixation. ④Adjust the absorption of trace elements by crops. When the soil pH is maintained at 6 to 7, trace nutrients will maintain a certain effectiveness on crops. ⑤ Improve the physical properties of soil, mainly improving the particle size distribution of soil. Common calcium magnesium phosphate fertilizers (see phosphate fertilizers) also have the above effects.
Sulfur-containing fertilizers are mainly used to adjust the alkalinity and salinity of the soil (the soil contains too much sodium chloride and carbonate). A large amount of calcium sulfate (gypsum) is used to improve saline-alkali soil or soil flooded by seawater, and has good results. Pyrite has been used successfully in India to improve alkaline or calcareous soils. For some magnesium-deficient soils with high pH, ??it is not suitable to apply dolomite powder. Instead, magnesium sulfate or anhydrous magnesium vitriol can be applied, or serpentine magnesium silicate powder can be used. In recent years, a new technology has been developed to coat the surface of urea particles with molten elemental sulfur. On the one hand, it provides sulfur elements to the soil, and on the other hand, it makes urea a slow-acting nitrogen fertilizer to improve nitrogen utilization.
Biological fertilizer
What is biofertilizer? Existing biofertilizers are based on organic matter, and then mixed with bacterial agents and inorganic fertilizers. To broadly improve this general and traditional situation, biofertilizer products go far beyond existing concepts. It will be expanded to provide crop nutrition and improve the soil; at the same time, the soil should be disinfected, that is, using organisms (mainly microorganisms) to decompose and eliminate pesticides (insecticides and fungicides), herbicides and It removes pollutants from petrochemical and other products, and at the same time plays a remedial role in soil.
Biofertilizer in a narrow sense refers to microbial (bacterial) fertilizer, referred to as bacterial fertilizer, also known as microbial inoculant. It is fermented (artificially cultivated) by microorganisms with special effects. It contains a large number of beneficial microorganisms. When applied to the soil, it can fix nitrogen in the air, activate nutrients in the soil, and improve plant nutrition. The environment, or specific microbial products that produce active substances and stimulate plant growth during the life activities of microorganisms.
Biofertilizers in a broad sense generally refer to biological agents that are manufactured using biotechnology and have specific fertilizer effects (or fertilizer effects and stimulating effects) on crops. The active ingredients can be specific living organisms, organisms Metabolites or transformation products of substrates, etc. This organism can be either a microorganism or an animal or plant tissue or cell. Biological fertilizers, like chemical fertilizers and organic fertilizers, are important fertilizer sources in agricultural production.
The irrational application of large amounts of chemical fertilizers and chemical pesticides not only consumes a large amount of non-renewable resources, but also destroys the soil structure, pollutes the quality of agricultural products and the environment, and affects human health and survival. Therefore, judging from the development trend of green agriculture and ecological agriculture advocated in modern agricultural production, pollution-free biofertilizers that do not pollute the environment will surely play an important role in future agricultural production.
Classification of biofertilizers
According to the current products and types of microbial fertilizers, they can be divided into two categories:
(1) Through the microorganisms contained in them The life activities of plants increase the supply of plant element nutrients, including the total supply of plant nutrients and the effective supply of plant nutrients in the soil and production environment, leading to an improvement in plant nutritional status and an increase in yield. This type of microorganisms The representative variety of fertilizer is rhizobia fertilizer.
(2) Although its products also increase crop yields through the key role of the microbial life activities contained in them, the key role of the microbial life activities is not limited to improving the elemental nutrient supply level of plants, including them. The produced plant growth stimulating hormone stimulates plants, promotes the absorption of nutrients by plants, or antagonizes the pathogenic effects of certain pathogenic microorganisms, reducing crop diseases and insect pests and increasing yields. There are many types and products of this type of microorganisms, and they are also relatively complex. However, with the further development of research, such microorganisms and their products will have more reasonable and scientific attribution and classification.
Types of biofertilizers
There are many types of biofertilizers (microbial fertilizers). According to the specific types of microorganisms in the products, they can be divided into bacterial fertilizers (such as rhizobia fertilizers and nitrogen-fixing bacteria fertilizers). ), actinomycete fertilizers (such as antibiotic fertilizers), fungal fertilizers (such as mycorrhizal fungi); according to their mechanism of action, they are divided into rhizobium fertilizers, nitrogen-fixing bacteria fertilizers (autonomous or combined with bacteria), phosphate-solubilizing bacteria Microbial fertilizers, silicate fungus fertilizers; according to the content of their products, they are divided into single microbial fertilizers and compound (or compound) microbial fertilizers. Compound microbial fertilizers include bacteria, bacteria compound, and bacteria and various additives.
The main varieties currently on the market in China are: nitrogen-fixing bacteria fertilizers, rhizobium fertilizers, phosphorus-solubilizing microbial fertilizers, silicate bacterial fertilizers, photosynthetic bacteria fertilizers, Bacillus preparations, and decomposing crop straw preparations , microbial growth regulators, compound microbial fertilizers, preparations used in combination with PGPR, AM mycorrhizal fungus fertilizers, antibiotic 5406 fertilizers, etc.
Characteristics of biofertilizers: Microbial fertilizers are a type of live bacteria products, and their efficiency is directly related to the activity of the fungi and the method of use.
(1) The core of microbial fertilizers refers to specific varieties of effective living microorganisms. The effective number of viable bacteria in any product is clearly defined. When the number of effective viable bacteria drops to a certain number, it The effect is gone.
(2) Microbial fertilizer is a type of agricultural live bacterial preparation. From production to use, attention must be paid to giving the microorganisms in the product a suitable environment for survival, mainly moisture content, pH, temperature, and residual sugar in the carrier. content, packaging materials, etc.
(3) Microbial fertilizers, as live bacteria preparations, have an issue with their validity period. When these products are first produced, the content of viable bacteria is high. However, as the storage time and different transportation and storage conditions change, the number of effective microorganisms in the product gradually decreases. When it is reduced to a certain number, its effective effect cannot be displayed. Therefore, it is of great significance to stipulate the expiration date and correct use of products.
(4) Suitable crops and suitable areas are important guarantees for the effective effect of microbial fertilizers. Promote targeted breeding of production strains, such as strains for alkaline soils, acidic soils, or strains for a specific crop.
In addition, attention should be paid to the application technology, and it is also necessary to see whether the product has a market access certificate. Bio-organic compound fertilizer is a high-tech product processed by absorbing the essence of traditional organic fertilizer and combining it with modern biotechnology.
Its nutritional elements integrate quick-acting, long-lasting and synergistic effects, and can improve the quality of agricultural products, inhibit soil-borne diseases, enhance crop resistance and promote early maturity of crops. Its main features are:
Firstly, No pollution, no public hazard. Biocompound fertilizer is an effective combination of natural organic matter and biotechnology. The bacteria contained in it can accelerate the decomposition of organic matter and provide "power" for crops to produce or transform available nutrients. At the same time, the microbial agent has the function of improving the utilization rate of chemical fertilizers and activating potential nutrients in the soil.
Second, the formula is scientific and nutritious. Bio-organic compound fertilizers generally use organic matter as the main body, combined with a small amount of chemical fertilizers, scientifically proportioned according to the fertilizer requirements of crops and fertilizer characteristics, and perfectly combined with biological "activators". In addition to containing a large amount of nutrients such as nitrogen, phosphorus and potassium In addition to calcium, magnesium, sulfur, iron, boron, zinc, selenium, molybdenum and other medium and trace elements, it also contains a large amount of organic substances, humic acid substances and fertilizer-preserving synergists. It is complete in nutrients, fast and slow, and provides Balanced fertilizer, long-lasting fertilizer effect.
The third is to activate the soil and increase fertilizer efficiency. Biofertilizers help release latent nutrients in the soil. The conversion rate of nitrogen in soil can reach 5-13.6; the conversion rate of phosphorus and potassium in soil can reach 7-15.7 and 8-16.6.
Fourth is low cost and high output. In the third and fourth temperate zones with short growth periods, bio-organic compound fertilizers can replace chemical fertilizers for one-time fertilization, reducing production costs. For example, 30-40kg of special biological compound fertilizer is applied to soybeans per acre, and 50-75kg of special fertilizer is applied to corn per acre. They are applied as base fertilizer at one time and do not require top dressing, which saves investment and work. Compared with conventional application of chemical fertilizers, with equivalent inputs, grain crop yields can increase by 10-20% per mu.
The fifth is to improve product quality and reduce harmful accumulation. Due to the dual effects of the activator and fertilizer-preserving synergist in biocompound fertilizer, it can promote the conversion of nitrates in crops and reduce the accumulation of nitrates in agricultural products. Compared with the application of chemical fertilizers, the nitrate content in the product can be reduced by 20-30%, the VC content can be increased by 30-40%, and the soluble sugar can be increased by 1-4 degrees. The product tastes good, stays fresh for a long time, and is durable in storage.
The sixth is to effectively increase the fertility of cultivated land and improve the soil fertilizer environment. The exosporic polysaccharide overflowed from the activated bacteria in the biofertilizer is the binder of the soil aggregate structure. It can loosen the soil, strengthen the soil aggregate structure, improve the water and fertilizer retention capacity, increase soil organic matter, and activate potential nutrients in the soil.
The seventh is to suppress soil-borne diseases. Biofertilizer can promote the proliferation of beneficial microorganisms in the rhizosphere of crops and improve the ecological environment of the rhizosphere of crops. The increase in beneficial microorganisms and disease-resistant factors can also significantly reduce the infection of soil-borne diseases and reduce the disease index of repeated crops. Application in successive years can greatly alleviate obstacles to continuous cropping.
The eighth is to promote early maturity of crops.
The role of biofertilizers: The efficacy of biofertilizers (microbial fertilizers) is a comprehensive effect, mainly related to the source and availability of nutrient elements, or to the absorption of nutrients, water and disease resistance (insects) of crops. )related. Generally speaking, the functions of biofertilizers (microbial fertilizers) are as follows:
1. Improve soil fertility. Applying nitrogen-fixing microbial fertilizers can increase the source of nitrogen in the soil; phosphorus-solubilizing and potassium-solubilizing microbial fertilizers , which can decompose insoluble phosphorus and potassium in the soil and transform them into phosphorus and potassium compounds that crops can absorb and utilize, improving the nutritional conditions of crops.
2. Produce and assist crops in absorbing nutrients. Rhizobium infects the roots of leguminous plants and fixes nitrogen in the air. Microorganisms can produce a large amount of plant growth hormones during reproduction, which stimulate and regulate crop growth, make plants grow strong, and promote the absorption of nutrients.
3. Enhance plant disease resistance and drought resistance. Microbial fertilizers inhibit or reduce the reproduction opportunities of pathogenic microorganisms due to their large growth and reproduction in the roots of crops; they can resist pathogenic microorganisms and reduce crop diseases; a large number of microorganisms The mycelium can increase the absorption of water and improve the drought resistance of crops.
4. Reduce the use of chemical fertilizers and improve crop quality. The use of microbial fertilizers has a certain effect on improving the quality of agricultural products, such as protein, sugar, vitamins, etc., and some can reduce the accumulation of nitrates. In some cases, improvements in quality are more beneficial than increases in yield.
Organic fertilizer
Organic fertilizer (manure) is a type of fertilizer made from natural organic matter decomposed or fermented by microorganisms. Also known as farmyard manure in China. Its characteristics include: wide sources of raw materials and large quantities; complete nutrients and low content; the fertilizer effect is late and long-lasting, and must be decomposed and transformed by microorganisms before it can be absorbed by plants; and the soil improvement effect is good. Commonly used natural fertilizer varieties include green manure, human excrement, manure, compost, retting fertilizer, biogas fertilizer and waste fertilizer.