Potassium has a ratio of 1-4% in crop dry matter, and it has many nutritional functions. Potassium activates multiple enzymes (chemicals that regulate life). Therefore, it plays a vital role in the synthesis of carbohydrates and proteins. Potassium can improve the moisture status of crops and increase the ability of crops to resist drought, frost and frost and salt. Crops with an adequate supply of potassium are also less susceptible to disease.
The role of potassium fertilizer:
1. Promote the synthesis of carbohydrates
When potassium is insufficient, the sucrose and starch in the plant are hydrolyzed to monosaccharides, and when potassium is sufficient, the starch synthase is activated, and the monosaccharide is carried out in the direction of synthesizing sucrose and starch.
Potassium can promote the process of sugar in the direction of polymerization, which is beneficial to the synthesis of fibers. Therefore, potassium fertilizer has an important role in cotton, hemp and other fiber crops.
2. Promote the transportation of photosynthetic products
Potassium can promote the transport of photosynthetic products to the fruit, and the fruit expands rapidly.
3. Coordinate the interrelationship between the "source" and the "library"
Common potash fertilizers:
Potassium chloride KCl: contains K2O 50-60% (contains K 52%, Cl 47.6%).
Properties: white, light yellow or purple red crystals, easily soluble in water, chemically neutral, hygroscopic, long-term storage will agglomerate, physiological acidic fertilizer. It should be used as a base fertilizer, applied on acidic soil, preferably with the use of organic fertilizers, saline and alkaline land should not be applied, and chlorinated crops should not be applied.
Potassium sulfate K2SO4: contains K2O 50%-54% (contains K43.8%, S 17.6%).
Properties: white or light yellow crystals, soluble in water, chemical acidity, moisture absorption is small, physiological acidic fertilizer. Potassium sulfate is suitable for all kinds of crops, especially potassium-free crops, and should be properly concentrated when applied.
Potassium nitrate KNO3: contains K2O 45%-46% (contains K 38%-39%).
Properties: white powder or crystallization; soluble in water, chemically neutral; hygroscopicity is small.
Potassium dihydrogen phosphate KH2PO4: contains K2O 34%-35% (contains K 28%-29%).
Properties: colorless to white crystalline or crystalline powder, soluble in water, chemically acidic, stable in air, physiological acidic fertilizer. At present, it is mostly used for soaking seeds and topdressing outside the root, and the effect is very good.
Grass and wood ash: it is the residual ash after the burning of crop straw, dead branches and leaves, etc., and almost all nitrogen is lost during the combustion process, containing a variety of ash elements, such as potassium, phosphorus, calcium, magnesium, sulfur, silicon and various trace elements. Among them, potassium and calcium content are high, and it is customary to regard grass and wood ash as potassium fertilizer. The form of potassium in grass and wood ash is mainly potassium carbonate, about 90% soluble in water, is a quick-acting potassium fertilizer, so it should be stored and used to prevent rain, so as not to cause nutrient loss.
Biological potassium fertilizer is a silicate bacterial agent, it can be used to mix seeds, dip roots, can also be applied in the soil, the application of bacterial agents is actually for the crop root inoculation, so that silicate bacteria will be around the root soil potassium, phosphorus, silicon, iron and other elements released by the root system to be absorbed and utilized by the roots.
Precautions for the use of potassium fertilizer:
First, according to the soil application. Due to the current shortage of potassium fertilizer resources, potassium fertilizer should first be put in areas with severe potassium deficiency in the soil. In general, when the soil available potassium is lower than 80mg/kg, the effect of potassium fertilizer is obvious, and potassium fertilizer should be increased; when the soil available potassium is 80~120mg/kg, potassium is not applied for the time being. From the perspective of soil texture, the available potassium content of sandy soils is often low, and potassium fertilizer should be increased: the available potassium content of clay soils is often higher, and it can be applied less or not. Potassium sulfate can be applied to soils that are deficient in potassium and sulfur, but potassium chloride cannot be applied to saline-alkaline soils.
Second, due to crop application. It is applied to potassium-loving crops such as legumes, potato crops, cotton and hemp, tobacco and other cash crops, as well as corn of cereals. In rainy areas or with irrigation conditions, good drainage conditions in most crops can be applied potassium chloride, a small number of cash crops to improve the quality, should not be applied potassium chloride, according to the requirements of agricultural production on the product traits and their use to determine the rational application of potassium fertilizer, in addition, due to the different amount of potassium demand of different crops and the different ability of the root system to absorb potassium, the degree of response of crops to potassium fertilizer is also different, from the results of the application of potassium fertilizer for many years, corn, cotton, sweet potato, oil crops, potassium fertilizer yield increase effect is the best, Other crops, such as wheat, are on the other.
Third, pay attention to the rotation of potassium. In the rotation of winter wheat and summer corn, potassium fertilizer should be preferentially applied to corn.
Fourth, pay attention to the reasonable collocation between potash varieties. For tobacco, sugar crops, fruit trees should be selected potassium sulfate is better; for fiber crops, potassium chloride is more appropriate. Due to the high cost of potassium sulfate, potassium sulfate can be used in high-efficiency cash crops, and for general field crops, except for a few crops that are sensitive to chlorine, it is advisable to use less expensive potassium chloride
Types of fat
Potassium-containing minerals, especially soluble potash minerals, are the main raw materials for the production of potash fertilizers, and potassium fertilizers can also be extracted from salt lake water, salt well water and brine.
About the naming of potash fertilizers
Potassium fertilizer belongs to a strong alkali acid, its name and its corresponding what acid, and nitrate corresponding to potassium nitrate, and sulfate corresponding to potassium sulfate, and hydrochloric acid (also called hydrochloric acid) corresponding to potassium chloride, and carbonate corresponding to potassium carbonate, and phosphate corresponding to potassium phosphate (monostasium phosphate, dipotassium phosphate, tripotassium phosphate, potassium polyphosphate, potassium polyphosphate, etc.), and organic acid corresponding to called organic potassium (potassium formate, potassium acetate, potassium citrate, etc.), and silicate corresponding to called potassium silicate ...
Main products
plant ash
It mainly contains potassium, phosphorus, calcium, magnesium, sulfur, silicon and various trace elements, but mainly potassium and calcium. It is a fast-acting alkaline potassium fertilizer. Rain blisters should be avoided during storage. It should not be mixed with ammonium nitrogen fertilizers, water-soluble phosphate fertilizers and fully decomposed organic fertilizers (such as human and animal urine). Rich in calcium, it cannot be mixed with calcium superphosphate and mixed. It is suitable for all kinds of soils except saline-alkaline soils, especially for acidic soils.
Grass and wood ash can be used as base fertilizer, topdressing and cover seed fertilizer, and can also be used for extra-root topdressing. The dosage is 50 ~ 100kg / mu, and a small amount of water should be added to make it moist before application. When making base fertilizer, it should be applied intensively, using ditch application or hole application, and covering the soil after application. When topdressing, foliar spraying can be done. When used as cover seed fertilizer, it is used as a vegetable seedbed cover. Use 1% grass and wood ash water leaching solution for extra-root topdressing, which can also prevent aphids.
potassium chloride
With a potassium content of 60% and a commercial fertilizer content of 50% to 60%, it is suitable for various soils except saline-alkaline soils. Attention should be paid to the application of organic fertilizers, calcium- magnesium and phosphate fertilizers, phosphate rock powders or other alkaline fertilizers on acidic soils or soils with long-term large amounts of potassium chloride. Long-term application of potassium chloride on neutral soil should be accompanied by calcium fertilizer. Under the conditions of cultivation of melons, fruits and vegetables and protected land, potassium chloride should be applied according to the reasonable or small amount of crop and soil conditions, and the application of dichlorinated fertilizers made of potassium chloride and ammonium chloride is strictly prohibited. During the dry season, the amount of potassium applied to the soil needs to be appropriately increased.
It can be used as base fertilizer and topdressing, and should not be used as seed fertilizer. When making base fertilizer, it should be used in conjunction with organic fertilizer and phosphate rock powder on neutral and acidic soil. When topdressing, it should be applied early, and the amount of application is generally 5 to 15kg/mu. The amount of base fertilizer applied can be slightly more than topdressing. Chlorine-sensitive crops such as potatoes should not be applied, and potassium fertilizers without chloride ions such as potassium sulfate can be used.
Advantages: low price, high potassium content, good instant solubility, neutral fertilizer.
Disadvantages: dissolved heat absorption, easy moisture absorption, chlorine, a large number of long-term administration has certain side effects.
potassium sulfate
Potassium content 48% ~ 52%, sulfur content 18%, light gray or slightly yellow, soluble in water, high concentration of fast-acting potassium fertilizer, suitable for a variety of crops and soils, especially suitable for chlorine, sulfur-loving crops, such as potatoes, potatoes, onions and garlic and so on. On acidic soil or long-term application, calcium, magnesium and phosphate fertilizer, phosphate rock powder or other alkaline fertilizers should be applied to prevent soil acidification and compaction. It is applied to sulfur-deficient soils and vegetables with more sulfur needs, such as onions, leeks, and garlic, and has a good effect, so it should first be used for crops that are sensitive to chlorine and potassium and sulfur. It should not be applied in aquatic vegetables. Applied on neutral and calcareous soils, organic fertilizers should be applied in conjunction with the application of organic fertilizers. For sandy soils with poor water retention and fertilizer retention ability, they should be applied separately by combining base fertilizer and topdressing.
It can be used as base fertilizer, topdressing, seed fertilizer and foliar fertilizer. It is advisable to apply it early for topdressing. When making base fertilizer and topdressing, the centralized fertilization method of strip application, ditch application and hole application is adopted, and the application amount is 7.5~15kg/mu. The amount of seed fertilizer used is 1.5~2.5kg/mu. Foliar fertilization concentration was 2% to 3%.
Advantages: low price, high potassium content, not easy to absorb moisture, can provide sulfur elements.
Disadvantages: dissolved heat absorption, weak acidity, physiological acid fertilizer, the sulfur contained in it is easy to combine with calcium to form a micro-soluble calcium sulfate, which can cause soil acidification and compaction after application.
Potassium dihydrogen phosphate
52% phosphorus content, about 34% potassium content, is a chemically neutral, physiologically neutral fertilizer, with good water solubility. Generally before and after flowering, it can be used to promote root germination and flower bud differentiation, and provide energy for flowering and fruit setting; the use of coloring period can promote pink coloring and increase the sweetness of the fruit; the use of fruit after picking can promote the old ripening of branches and improve the degree of lignification of the fruit.
It can be used for seed soaking, seed mixing, root dipping, root irrigation, foliar spraying, and root application. It is economical and more effective to use during critical periods of crop growth. For example, seeds are soaked and mixed before sowing; the jointing stage, budding stage and pregnant ear stage of grain crops; and the seedling stage and full flowering period of cotton, rapeseed, peanuts, vegetables and potatoes are used best.
Advantages: not easy to absorb moisture, high total content of phosphorus and potassium, is currently a high content of powder water-soluble fertilizer in the necessary raw materials. At the same time, phosphorus and potassium are supplemented, and the dosage is small, and the effect is obvious.
Disadvantages: If you have to say it, it is a bit more fakes ~! When purchasing, please look for regular manufacturers
potassium nitrate
Containing 13.5% nitrogen in nitrate and 46% potassium, it is a chemically neutral and physiologically neutral fertilizer with good water solubility and long-term application, which will not lead to soil acidification. It is suitable for the expansion stage of young fruits in fruit trees to the early stage of coloring, and can promote the expansion of pulp cells. Because it contains nitrate nitrogen, it is not recommended to use it in the later stage of coloring, which is easy to cause rejuvenation.
It is easy to move in the soil and is suitable for crop topdressing, especially in the middle and late stages of topdressing.
Advantages: moderate price, good instant solubility, not easy to absorb moisture, neutral fertilizer, providing fast absorption of nitrate nitrogen.
Disadvantages: dissolved heat absorption to reduce ground temperature, under adversity, it is easy to cause the accumulation of nitrite in the crop body (organic agriculture is prohibited), which is nitrate, and has certain safety hazards in the storage and processing process.
Effective application of potassium fertilizers
The effective application technology of potassium fertilizer is affected by a variety of factors, among which soil type, fertility level, crop type, fertilization method and other factors are greatly affected.
Potassium is applied to the soil
The degree of soil potassium deficiency is a prerequisite for the effective application of potassium fertilizer, and the effect of soil available potassium content on potassium fertilizer efficiency should be considered first. The size of the potash fertilizer is closely related to the abundance of available potassium in the soil, that is, under the same conditions as other conditions, the lower the soil available potassium content, the better the fertilizer efficiency of the potash fertilizer in the current season.
Soil available potassium content is less than 40 mg / kg for the soil of extreme potassium deficiency, potassium has become a limiting factor for crop yield increase, should be given priority, per mu dosage (K2O) 5 ~ 10 kg, fold potassium chloride or potassium sulfate 10 ~ 20 kg, no matter what soil and crop, the yield increase effect is very significant. When the soil available potassium content is 40~80 mg/kg, it is potassium-deficient soil, and the potassium fertilizer dosage per mu is about 5 kg, and the yield increase effect is also significant. When soil available potassium content is greater than 80 mg/kg, except for some potassium-loving cash crops, food crops can be applied less or no. At the same time, the content of soil slow potassium, soil texture and degree of maturation should also be considered.
Soil potash can not be directly absorbed and utilized by crops, is the source and reserve of soil available potassium, in the case of similar soil available potassium content, the lower the soil potash content, the slower the conversion into available potassium. The fertilizer efficiency of applying potassium fertilizer tends to be better. However, as a guide to the application of potassium in the current season, the soil available potassium content is the main basis.
Coarse sandy soils, due to the low potassium content, coupled with the available potassium in the soil and easy leaching loss, the effect of potassium application on such soils is often better than that of cohesive soils, and the fertilizer efficiency of potassium fertilizer in soils with high degree of maturation is generally not as good as that of soils with low degree of curing. Because the former is rich in potassium, and has good soil physical and chemical properties, potassium supply capacity is strong. The soil in southern China has a low potassium content, and the focus of potassium fertilizer application should be in the south; but the area of soil potassium deficiency in the north is gradually expanding, especially in some high-yield soils, and the phenomenon of potassium deficiency is becoming increasingly serious.
Potassium is applied as a result of crop
In the case of soil potassium deficiency, potassium fertilizer should be preferentially used on potassium-loving crops, the order of potassium-loving crops, legumes> potatoes, sugar beets, sugar cane, watermelon, fruit trees> cotton, hemp, tobacco> corn> rice, wheat. Potassium-loving crops are relative, in the soil of severe potassium deficiency, no matter what crops are planted, the effect of potassium application is significant, and on potassium-rich soils, potassium-loving crops often do not increase yield.
Different varieties of the same crop also react differently to potassium fertilizer, taking rice as an example, hybrid rice, dwarf high-yielding fine stalk rice increased the fertilizer efficiency of potassium fertilizer than high-stalk varieties, Shantou rice and conventional rice.
Crops such as soybeans, oil, wheat, fruit trees and rice can enhance cold resistance and reduce frost damage and increase yield in harsh environments such as cold, drought and insufficient sunlight, and increase or apply potassium fertilizer early. For example, in the black soil of northeast China, the content of available potassium and slow potash is higher, but in recent years, the test of soybeans on black soil has shown that the application of potassium fertilizer in cold and dry years has enhanced the effect of soybean cold resistance and drought resistance, and the fertilizer efficiency is also more obvious.
The amount of potassium fertilizer applied
The amount of potassium fertilizer also follows the phenomenon of decreasing remuneration. On potassium-deficient soils, crop yields increase with potassium application, while yield increases per kilogram of potassium fertilizer decrease with increased use. When the dosage exceeds a certain range, the yield cannot be further increased.
The appropriate amount of potassium fertilizer should be determined by the balance of soil available potassium content, crop types and various nutrient disorders. In the current case of relatively little potassium fertilizer, it is generally impossible to fully meet the needs of crops, and it is advisable to use 3 to 6 kg of potassium fertilizer per mu (K2O). In potassium-deficient soils, rice yields are generally increased by 5 to 10 kg per kilogram (K2O). The seasonal utilization rate of potash fertilizer is 40% to 50%. Crops with serious potassium deficiency and potassium-loving soil, such as soybeans, sweet potatoes, tobacco, sugarcane and other potassium fertilizers, can be appropriately increased, and the amount of potassium fertilizer in the soil is not serious and the amount of farm manure is sufficient, potassium fertilizer can be applied less or not.
Application period of potassium fertilizer
Potassium fertilizer can be used as base fertilizer, seed fertilizer or topdressing. Potassium fertilizer, like phosphate fertilizer, is better with base fertilizer or early topdressing, because the seedling stage value of the crop is the critical stage of potassium, and the response to potassium is very sensitive. Although the potassium absorption of crops at the seedling stage is less than 1% of the total growth period, the individuals at the seedling stage are small and the relative number is large.
The application method of potassium fertilizer
(1) After spreading, use a plough to turn and press into the soil
(2) Fertilize with seeds or strips near seeds when sowing
(3) Shallow cultivation after application (harrowing land or field)
(4) Acupuncture
(5) Surface sprinkling
(6) Foliar spraying
Source: Meng Baolong Great Agriculture.