What are the types and functions of common fertilizers?

Fertilizer is a substance that provides one or more essential nutrients for plants, improves soil properties and improves soil fertility. One of the material bases of agricultural production. China knew as early as the Western Zhou Dynasty that weeds rotted in the fields could promote the growth of millet. The method of planting green manure and the method of rotation between leguminous crops and gramineous crops are introduced in detail in Qi Yao Min Shu. The method of mixing, trampling and composting crop straw with cow dung and urine is also mentioned.

What are the types and functions of common fertilizers?

Ammonium phosphate fertilizer

A nitrogen-phosphorus compound fertilizer is prepared by neutralizing phosphoric acid (including polyphosphoric acid) and ammonia. This is the largest and most popular fertilizer, suitable for almost all soils and crops. The concentration of effective components is high, and it is not easy to absorb moisture and agglomerate. Ammonium phosphate can also be used as flame retardant for fabrics and fibers, culture solution for fermentation industry, food additive and feed additive, acidulant for printing and dyeing industry, and ingredient for dry powder fire extinguishing agent for fire fighting. The production technology of ammonium phosphate fertilizer is the combination of phosphate fertilizer production technology and ammonia processing technology in nitrogen fertilizer production, which is reasonable in economy.

The industrial production of ammonium phosphate began in the 1920s, but the scale was very small. In the early 1960s, the production technology of wet-process phosphoric acid tended to be perfect, ammonium phosphate raw materials were cheaper, and the production developed very rapidly, especially in the United States. 1968 The output of ammonium phosphate fertilizer in the United States (calculated as P2O5) is about half of the total output of phosphate fertilizer, and it increases to 74. 19 1% per year.

The varieties of ammonium phosphate fertilizer can be divided into three categories (see the table below). ① Ammonium orthophosphate with the largest output mainly includes diammonium phosphate, monoammonium phosphate and their mixtures. (2) Ammonium polyphosphate is a mixture of ammonium orthophosphate and ammonium phosphate salts with different polymerization degrees, and most of them are used to make fluid fertilizer. ③ Compound fertilizer made of ammonium phosphate and other nitrogen fertilizers.

Macroelement water-soluble fertilizer

Water-soluble fertilizer (WSF) is a multi-component compound fertilizer that can be completely dissolved in water. Can be quickly dissolved in water, is easily absorbed by crops, and has high absorption and utilization rate. More importantly, it can be applied to facilities agriculture such as spray and drip irrigation to realize the integration of water and fertilizer and achieve the efficiency of saving water, fertilizer and labor. Generally speaking, water-soluble fertilizers can contain all nutrient elements needed for crop growth, such as nitrogen, phosphorus, potassium, calcium, magnesium, sulfur and trace elements. In this way, people can design the formula according to the characteristics of crop growth and nutrition demand, and the scientific formula will not cause fertilizer waste, making its fertilizer utilization rate almost 2-3 times that of conventional compound fertilizer (in China, the fertilizer utilization rate of common compound fertilizer is only 30%-40%). Secondly, water-soluble fertilizer is a kind of quick-acting fertilizer, which allows growers to quickly see the effect and performance of fertilizer and adjust the fertilizer formula at any time according to the different growth conditions of crops. Of course, the application method of water-soluble fertilizer is very simple. Can be used in conjunction with irrigation water, including sprinkler irrigation and drip irrigation, saving water, fertilizer and labor. In today's rising labor costs, the benefits of using water-soluble fertilizers are obvious. Because the application mode of water-soluble fertilizer is irrigation with water, it makes fertilization extremely uniform and lays a solid foundation for improving yield and quality. Generally, water-soluble fertilizers have few impurities, low conductivity and convenient concentration adjustment, and are safe even for seedlings, so there is no need to worry about adverse consequences such as burning seedlings. At the same time, the author believes that according to the requirements of crops, a large number of element water-soluble fertilizers must have the following technical characteristics:

● The composition of water-soluble chelating trace elements added in the composition should avoid antagonism with phosphorus.

● For crops, it has the characteristics of stress resistance and yield increase, which can significantly improve crop photosynthesis, improve crop yield and quality, increase sugar, enhance cold resistance, drought resistance, disease resistance and lodging resistance, and extend shelf life.

Adding high potassium formula can quickly meet the demand for potassium when fruits and seeds swell, increase the sweetness of fruits, improve the coloring of fruits and prolong the storage time.

Medium element fertilizer

Also known as trace and macro-element fertilizer, it contains one or more compounds of crop nutrients such as calcium, magnesium and sulfur, and its content should be marked. The production and application scale of minor constants and major constants of nitrogen, phosphorus and potassium were compared. China is known as the medium element fertilizer. This fertilizer can not only provide crops with nutrients, but also adjust the physical properties of soil and promote agricultural production. For a long time, the production of medium element fertilizer has been ignored by people. The reason is that some commonly used fertilizer varieties, especially low-concentration fertilizer varieties, contain calcium, magnesium or sulfur at the same time. Sulfur dioxide in the atmosphere enters the soil through rainwater and is also one of the sources of sulfur. In recent 30 years, high-concentration fertilizers have gradually replaced low-concentration fertilizers in the variety structure of chemical fertilizers, reducing the calcium, magnesium and sulfur elements brought into the soil, and some soils lack medium nutrients, especially sulfur elements, which makes the production and use of medium-element fertilizers pay attention. Limestone powder, dolomite powder, hydrated lime, shell powder and other industrial wastes containing calcium and magnesium are widely used as soil improvers and provide calcium and magnesium nutrients. Its soil conditioning function is: ① to improve the availability of phosphate fertilizer in soil. In the soil with high iron and aluminum oxide, the effectiveness of phosphate fertilizer is reduced due to the reaction between phosphate and iron and aluminum compounds. Applying calcium and magnesium conditioner to keep the soil pH at 6 ~ 7 can slow down the above reaction. ② It is beneficial to transform ammonium nitrogen into nitrate nitrogen in soil, and most nitrifying bacteria need calcium. ③ The process of promoting biological nitrogen fixation. (4) Adjust the amount of trace elements absorbed by crops. When the soil pH value is kept at 6 ~ 7, trace elements remain effective for crops. ⑤ Improving the physical properties of soil is mainly to improve the particle size distribution of soil. Common calcium magnesium phosphate fertilizer (see phosphate fertilizer) also has the above effect.

Sulfur-containing fertilizers are mainly used to adjust the alkalinity and salinity of 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 submerged by seawater, and the effect is good. India has successfully improved alkaline soil or calcareous soil with pyrite. For some magnesium-deficient soils with high pH value, dolomite powder is not suitable. Magnesium sulfate or anhydrous potassium magnesium alum can be used, and serpentine magnesium silicate powder can also be used. In recent years, a new technology has been developed, in which molten elemental sulfur is coated on the surface of urea particles. On the one hand, it provides sulfur for the soil, on the other hand, urea becomes a slow-acting nitrogen fertilizer, which improves the utilization rate of nitrogen.

Biological fertilizer

What is biological fertilizer? The existing biological fertilizers are mainly organic matter, and then mixed with microbial agents and inorganic fertilizers. In order to improve this universal and traditional situation, bio-fertilizer products go far beyond the existing concepts. It will be expanded to not only provide crop nutrition, but also improve the soil; At the same time, it is necessary to disinfect the soil, that is, use organisms (mainly microorganisms) to decompose and eliminate pesticides (pesticides and fungicides), herbicides and petrochemical pollutants in the soil, and at the same time play a role in repairing the soil.

Biological fertilizer in a narrow sense refers to microbial (bacterial) fertilizer, referred to as bacterial fertilizer, also known as microbial inoculum. It is made of microorganisms with special effects through fermentation (artificial culture) and contains a large number of beneficial microorganisms. After being applied to the soil, it can not only fix nitrogen in the air, activate nutrients in the soil, improve the nutritional environment of plants, but also produce active substances in the life activities of microorganisms and stimulate the growth of plants.

Broadly speaking, biofertilizer refers to a biological agent which is made by biotechnology and has specific fertilizer effect (or fertilizer effect and stimulating effect) on crops. Its effective components can be specific living organisms, metabolites or substrates of organisms, etc. This organism can be microorganisms, animal and plant tissues and cells. Biological fertilizer, like chemical fertilizer and organic fertilizer, is an important fertilizer source in agricultural production. The unreasonable application of chemical fertilizers and pesticides not only consumes a lot of non-renewable resources, but also destroys the soil structure, pollutes the quality of agricultural products and the environment, and affects the healthy survival of human beings. Therefore, judging from the development trend of green agriculture and ecological agriculture advocated by modern agricultural production, pollution-free biological fertilizers that do not pollute the environment will certainly play an important role in future agricultural production.

Classification of biological fertilizers

According to the current products and types of microbial fertilizers, they can be divided into two categories:

(1) Through the life activities of microorganisms contained in it, the supply of plant nutrients is increased, including the total supply of plant nutrients in soil and production environment and the effective supply of plant nutrients, thus improving the nutritional status of plants and increasing the yield. The representative variety of this microbial fertilizer is rhizobia fertilizer.

(2) Although its products also lead to the increase of crop yield through the key role of microbial life activities, the key role of microbial life activities is not limited to improving the nutrient supply level of plants, including the stimulating effect of plant growth stimulators produced by them on plants, promoting the absorption of nutrients by plants, or antagonizing the pathogenic effects of some pathogenic microorganisms, reducing crop diseases and insect pests, thus leading to the increase of crop yield. There are many kinds and products of these microorganisms, and they are also very complicated. However, with the in-depth development of research, such microorganisms and their products will have a more reasonable and scientific attribution and classification.

Types of biological fertilizers

There are many kinds of biological fertilizers (microbial fertilizers), which can be divided into bacterial fertilizers (such as rhizobia fertilizers and nitrogen-fixing bacteria fertilizers), actinomycetes fertilizers (such as antibiotic fertilizers) and fungal fertilizers (such as mycorrhizal fungi) according to the specific microbial types in the products; According to its action mechanism, it can be divided into rhizobia fertilizer, nitrogen-fixing bacteria fertilizer (autotrophic or combined), phosphorus-dissolving bacteria fertilizer and silicate bacteria fertilizer; According to its product content, it can be divided into single microbial fertilizer and compound (or mixed) microbial fertilizer. Compound microbial fertilizer is composed of bacteria, bacteria and various additives.

At present, the varieties appearing in China's market mainly include: nitrogen-fixing bacteria fertilizer, rhizobia fertilizer, phosphate-solubilizing microbial fertilizer, silicate bacteria fertilizer, photosynthetic bacteria fertilizer, Bacillus preparation, crop straw decomposition preparation, microbial growth regulator, compound microbial fertilizer, preparation used in conjunction with PGPR, AM mycorrhizal fungal fertilizer, antibiotic 5406 fertilizer and so on.

Characteristics of biological fertilizer: Microbial fertilizer is a kind of live bacteria product, and its efficacy is directly related to its fungal activity and dosage.

(1) The core of microbial fertilizer refers to the effective living microorganisms of a specific variety. The effective viable count of any product is clearly defined. When the number of effective viable bacteria drops to a certain number, its function will be lost.

(2) Microbial fertilizer is a kind of agricultural viable bacteria preparation. From production to use, we should pay attention to giving the microorganisms in the product a suitable living environment, mainly including moisture content, pH value, temperature, residual sugar in the carrier, packaging materials and so on.

(3) As a viable bacterial preparation, microbial fertilizer has an expiration date. The content of viable bacteria in this kind of products is high at the beginning of production, but with the change of storage time and different transportation and storage conditions, the number of effective microorganisms in the products gradually decreases, and its effective function cannot be exerted when it is reduced to a certain number. 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 to ensure the effective function of microbial fertilizers. Advocate targeted cultivation of production strains, such as strains for alkaline soil, acidic soil, or strains for specific crops.

In addition, we should pay attention to the application technology, and at the same time, we should see whether the products have market access certificates. Bio-organic compound fertilizer is a high-tech product that absorbs the essence of traditional organic fertilizer and combines modern biotechnology. Its nutrient elements are quick-acting, long-lasting and synergistic, and have the functions of improving the quality of agricultural products, inhibiting soil-borne diseases, enhancing crop stress resistance and promoting crop early maturity.

One is pollution-free, pollution-free Biological compound fertilizer is an effective combination of natural organic matter and biotechnology. The microbial inoculum contained in it can accelerate the decomposition of organic matter and provide "power" for crops to manufacture or transform available nutrients. At the same time, microbial agents can improve the utilization rate of chemical fertilizers and activate potential nutrients in the soil.

Second, the formula is scientific and the nutrients are complete. Bio-organic compound fertilizer is generally based on organic matter, with a small amount of chemical fertilizer, scientifically proportioned according to the law of crop fertilizer demand and fertilizer characteristics, and perfectly combined with biological "activator". It contains a lot of nutrients such as nitrogen, phosphorus and potassium, trace elements such as calcium, magnesium, sulfur, iron, boron, zinc, selenium and molybdenum, as well as a lot of organic matter, humic acid and fertilizer synergist, and has complete nutritional components.

The third is to activate soil and increase fertilizer efficiency. Bio-fertilizer can help release potential nutrients in the soil. The conversion rate of nitrogen in soil reached 5-13.6%; The conversion rates of phosphorus and potassium in soil can reach 7- 15.7% and 8- 16.6% respectively.

The fourth is low cost and high output. In the third and fourth accumulated temperature zones with short growth period, bio-organic compound fertilizer can replace chemical fertilizer for one-time fertilization and reduce production cost. For example, 30-40 kilograms of biological special compound fertilizer is applied to soybean and 50-75 kilograms of special fertilizer is applied to corn per mu, and it is used as base fertilizer at one time without topdressing, which saves investment and labor. Compared with conventional application of chemical fertilizer, under the condition of the same input, the yield of grain crops can be increased by 10-20% per mu.

Fifth, improve product quality and reduce harmful accumulation. Because biological compound fertilizer has the dual functions of activator and fertilizer-preserving synergist, it can promote the transformation of nitrate in crops and reduce the accumulation of nitrate in agricultural products. Compared with applying chemical fertilizer, 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 has good taste, long fresh-keeping time and storage resistance.

Sixth, effectively improve the fertility of cultivated land and improve the soil fertility environment. Extracellular polysaccharide overflowed by activated bacteria in biological fertilizer is the adhesive of soil aggregate structure, which can loosen soil, strengthen soil aggregate structure, improve water and fertilizer conservation ability, increase soil organic matter and activate potential nutrients in soil.

Seventh, inhibit soil-borne diseases. Biological fertilizer can promote crop rhizosphere benefits, microbial proliferation and improve crop rhizosphere ecological environment. The increase of beneficial microorganisms and disease resistance factors can also significantly reduce the infection of soil-borne diseases and the disease index of continuous cropping crops, and the continuous cropping obstacles can be greatly alleviated through continuous application.

Eight is to promote early maturity of crops.

Function of biological fertilizer: the function of biological fertilizer (microbial fertilizer) is a comprehensive function, which is mainly related to the source and effectiveness of nutrient elements, or to the absorption of nutrition and water and the resistance of crops to diseases (pests). Generally speaking, the functions of biological fertilizer (microbial fertilizer) are as follows:

1. Applying nitrogen-fixing microbial fertilizer can improve soil fertility and increase nitrogen sources in soil; Microbial fertilizer for dissolving phosphorus and potassium can decompose insoluble phosphorus and potassium in soil and transform them into phosphorus and potassium compounds that can be absorbed and utilized by crops, thus improving the nutritional conditions of crops.

2. Make and assist crops to absorb the roots of leguminous plants infected by vegetative rhizobia and fix nitrogen in the air. Microorganisms can produce a large number of plant growth hormones in reproduction, stimulate and regulate crop growth, make plants grow healthily and promote the absorption of nutrients.

3. Microbial fertilizers used to enhance plant disease resistance and drought resistance inhibit or reduce the reproductive opportunities of pathogenic microorganisms because they grow and reproduce in the roots of crops; Resist pathogenic microorganisms and reduce crop diseases; Microorganisms grow in large numbers, and hyphae can increase water absorption and improve the drought resistance of crops.

4. Reduce the use of chemical fertilizers and improve crop quality. The use of microbial fertilizers can improve the quality of agricultural products, such as protein, sugar and vitamins, and some can reduce the accumulation of nitrate. In some cases, the improvement of quality is more beneficial than the increase of output.

organic fertilizer

Manure is a kind of fertilizer made from natural organic matter by microbial decomposition or fermentation. China is also called farmyard manure. Its characteristics are: wide sources of raw materials, large quantity; Comprehensive nutrition and low content; Fertilizer efficiency is long and late, and it can only be absorbed by plants after microbial decomposition and transformation; The effect of improving soil fertility is good. Commonly used natural fertilizers include green manure, human excrement and urine, manure, compost, compost, biogas manure and waste manure.