The proportion of potassium in crop dry matter is 1-4%, which has many nutritional functions. Potassium activates a variety of enzymes (a life-regulating chemical). Therefore, it plays a vital role in the synthesis of carbohydrates and proteins. Potassium can improve the water condition of crops and increase the ability of crops to resist drought, frost, freeze and salt. Crops with sufficient supply of potassium are also less affected by disease.
The role of potash:
1. Promote the synthesis of carbohydrates
When potassium is insufficient, the sucrose and starch in the plant are hydrolyzed into monosaccharides; when potassium is sufficient, the starch synthase is activated, and the monosaccharide is carried out in the direction of synthesizing sucrose or starch.
Potassium promotes the progress of sugars in the direction of polymerization and is beneficial to the synthesis of fibers. Therefore, potassium fertilizer plays an important role in fiber crops such as cotton and hemp.
2. Promote the transportation of photosynthetic products
Potassium promotes the transport of photosynthetic products to fruits, and the fruit expands rapidly.
3. Coordinating the relationship between "source" and "library"
Common potash:
Potassium chloride KCl: containing K2O 50-60% (including K 52%, Cl 47.6%).
Properties: white, light yellow or purple red crystal; soluble in water, chemically neutral; hygroscopic, long-term agglomeration, physiological acid fertilizer. It should be used as base fertilizer and applied on acidic soil. It is best to use organic fertilizer in combination with salt and alkali. It is not suitable for application.
Potassium sulfate K2SO4: containing K2O 50%-54% (including K 43.8%, S 17.6%).
Properties: white or light yellow crystal; soluble in water, chemically acidic; low hygroscopicity; physiological acid fertilizer. It can be used as base fertilizer or top dressing. Potassium sulphate is suitable for all kinds of crops, especially for chlorhexidine potassium crops.
Potassium nitrate KNO3: containing K2O 45%-46% (including K 38%-39%).
Properties: white powder or crystal; soluble in water, chemically neutral; low hygroscopicity.
Potassium dihydrogen phosphate KH2PO4: containing K2O 34% -35% (including K 28%-29%).
Properties: colorless to white crystalline or crystalline powder; soluble in water, chemically acidic; stable in air; physiologically acidic fertilizer. Currently used for soaking and root dressing, the effect is very good.
Grass ash: It is the residual ash after burning of crop residues such as crop straw and litter. During the combustion process, almost all of the nitrogen is lost, containing various ash elements such as potassium, phosphorus, calcium, magnesium, sulfur, silicon and various Trace elements. Among them, potassium and calcium are abundant, and it is customary to regard grass ash as potash. The form of potassium in the plant ash is mainly potassium carbonate, about 90% soluble in water, is a quick-acting potassium fertilizer, so it should be protected from rain during storage and use, so as not to cause nutrient loss.
Bio-potassium fertilizer is a silicate bacterial microbial agent, which can be used for seed dressing, rooting, or application in soil. The application of microbial agents is actually inoculation of crop roots, allowing silicate bacteria to put potassium in the soil around the roots. Phosphorus, silicon, iron and other elements are released and absorbed and utilized by the roots.
Precautions for the use of potash:
First, due to soil application. Due to the current shortage of potash resources, potash should be first placed in areas where soil is seriously deficient in potassium. Generally, when the soil available potassium is lower than 80 mg/kg, the effect of potassium fertilizer is obvious, and potassium fertilizer should be added; when the soil available potassium is 80-120 mg/kg, potassium is not applied. From the perspective of soil texture, the available potassium content of sandy soil is often low, and potassium fertilizer should be added: the available potassium content of clay soil is often higher, and it can be applied less or not. Potassium sulphate can be applied to soils deficient in potassium and sulphur-deficient, and potassium chloride cannot be applied in saline-alkali soil
Second, due to crop application. It is applied to potassium crops such as legume crops, potato crops, cash crops, tobacco and other cash crops, as well as cereal corn. In rainy areas or areas with irrigation conditions and good drainage conditions, most crops can be applied with potassium chloride. A few economic crops are not suitable for the application of potassium chloride. According to the requirements of agricultural production for product traits and their use, potash is determined. Reasonable application.
In addition, due to the different potassium needs of different crops and the different potassium absorption capacity of the roots, the degree of response of the crops to potassium fertilizers is also different. From the results of many years of potash application, the yield increase of potassium fertilizer is best on corn, cotton, sweet potato and oil crops. Other crops such as wheat are second.
Third, pay attention to the rotation of potassium. In winter wheat and summer maize rotation, potassium fertilizer should be applied preferentially to corn.
Fourth, pay attention to the reasonable mix between potash varieties. Potassium sulphate should be used for tobacco, sugar crops and fruit trees. For fiber crops, potassium chloride is more suitable. Due to the high cost of potassium sulphate, potassium sulphate can be used on high-efficiency cash crops; for general field crops, except for a few chlorine-sensitive crops, cheaper potassium chloride should be used.
Type of fertilizer
Potassium-containing minerals, especially soluble potassium ore, are the main raw materials for the production of potash, and can also be extracted from salt lake water, salt well water and brine.
About the name of potash
Potassium fertilizer belongs to a strong acid salt, and its name depends on what acid root it corresponds to, and nitrate corresponds to potassium nitrate, and sulfate corresponds to potassium sulfate, and hydrochloric acid (also called hydrochloric acid) corresponds to Potassium chloride, which corresponds to carbonate, is called potassium carbonate, and phosphate is called potassium phosphate (potassium phosphate, dipotassium phosphate, potassium phosphate, potassium polyphosphate, potassium polyphosphate, etc.), corresponding to organic acid radicals. It is called organic potassium (potassium formate, potassium acetate, potassium citrate, etc.), and it is called potassium silicate corresponding to 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 quick-acting alkaline potassium fertilizer. Avoid rain and blisters when storing. It should not be mixed with ammonium nitrogen fertilizer, water-soluble phosphate fertilizer and fully decomposed organic fertilizer (such as human and animal urine). It is rich in calcium and cannot be mixed and mixed with superphosphate. Suitable for a variety of soils other than saline and alkaline soils, especially for acidic soils.
The grass ash can be used as a base fertilizer, top dressing and cover seed fertilizer, and can also be used for top dressing. The dosage is 50~100kg/mu, and a small amount of water should be added to make it moist before application. It should be applied intensively as a base fertilizer, using ditch or acupoint application, and applying soil after application. For top dressing, it can be sprayed on the foliar surface. Used as a vegetable seedbed cover when used as a seed fertilizer. Use 1% grass ash water leaching solution for root dressing, which can prevent mites.
Potassium chloride
The potassium content is 60%, and the commercial fertilizer content is 50% to 60%, which is suitable for various soils other than saline and alkaline soil. In the acidic soil or long-term application of potassium chloride to the soil, attention should be paid to the application of organic fertilizer, calcium magnesium phosphate fertilizer, phosphate rock powder or other alkaline fertilizer.
Long-term application of potassium chloride on neutral soil should be accompanied by calcium fertilizer. Potassium chloride should be applied reasonably or in small amounts according to the crop and soil conditions on the melon and fruit vegetables and under the cultivation conditions. It is strictly forbidden to apply the double-chlorine fertilizer made of potassium chloride and ammonium chloride. In the dry season, the amount of potassium applied to the soil needs to increase appropriately.
Can be used as base fertilizer, top dressing, not suitable for seed fertilizer. When used as a base fertilizer, it should be used in combination with organic fertilizer and phosphate rock in neutral and acidic soils. It should be applied early for topdressing, and the application rate is generally 5~15kg/mu. The application rate of the base fertilizer can be slightly more than the top dressing. Chlorine-sensitive crops such as potatoes are not suitable for application, and potassium chloride-free potassium fertilizers such as potassium sulfate may be used.
Advantages: low price, high potassium content, good instant solubility, neutral fertilizer.
Disadvantages: Dissolved heat absorption, easy to absorb moisture, chlorine, a large number of long-term application has certain side effects.
Potassium sulfate
Containing 48%~52% potassium, 18% sulfur, light gray or yellowish, soluble in water, high concentration of quick-acting potassium fertilizer, suitable for various crops and soil, especially suitable for avoiding chlorine and sulfur crops, such as Dioscorea, onion, garlic, etc. Calcium magnesium phosphate, phosphate rock or other alkaline fertilizer should be applied to acid soil or long-term application to prevent soil acidification and compaction.
It is effective in the application of sulfur-deficient soil and vegetables requiring more sulfur such as onion, leeks and garlic. Therefore, it should be used first on crops that are sensitive to chlorine and potassium. It is not suitable for application in aquatic vegetables. Applied on neutral and calcareous soils, combined with the application of organic fertilizers. The sandy soil with poor water retention and fertilizer retention capacity should be applied separately according to the base fertilizer and top dressing.
Can be used as base fertilizer, top dressing, seed fertilizer and foliar fertilizer. For top dressing, it should be applied early. For base fertilizer and topdressing, the method of concentrated application of strip application, ditch application and acupoint application is adopted, and the application amount is 7.5~15kg/mu. The amount of seed fertilizer is 1.5~2.5kg/mu. Foliar fertilization concentration is 2% to 3%.
Advantages: low price, high potassium content, not easy to absorb moisture, can provide sulfur.
Disadvantages: Dissolved endothermic, weakly acidic, physiologically acidic fertilizer, the sulfur contained easily combines with calcium to form a slightly soluble calcium sulfate, which can cause acidification and compaction of the soil after application.
Potassium dihydrogen phosphate
Containing 52% phosphorus and containing about 34% potassium, it is a chemically neutral, physiologically neutral fertilizer with good water solubility. Generally, it can be used to promote root germination and flower bud differentiation before and after flowering, and provide energy for flowering and fruit setting; the coloring period can promote the coloring of the powder and increase the sweetness of the fruit; the fruit can be used to promote the ripening of the branches and increase the degree of lignification of the fruit.
Can be used for soaking seeds, seed dressing, rooting, rooting, foliar application, root application. It is economical and more effective in the critical period of crop growth. For example, seed soaking and seed dressing before sowing; jointing stage, snoring stage and booting stage of grain crops; cotton, rapeseed, peanuts, vegetables, and potatoes have the best effect in seedling stage and full flowering stage.
Advantages: It is not easy to absorb moisture, and the total content of phosphorus and potassium is high. It is an essential raw material in high-content powder water-soluble fertilizer. At the same time, the phosphorus and potassium elements are added, and the dosage is small, and the effect is obvious.
Disadvantages: If you have to say it, it is a lot of fakes! Please look for regular manufacturers when purchasing.
Potassium nitrate
It contains 13.5% nitrate nitrogen and 46% potassium. It is a chemical neutral and physiological neutral fertilizer with good water solubility. It will not cause soil acidification after long-term application. It is suitable for the expansion of fruit trees from the expansion period to the early stage of coloring. Because it contains nitrate nitrogen, it is not recommended to use it later, which is easy to cause greening.
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 nitrate nitrogen absorption fast.
Disadvantages: Dissolving heat and lowering the temperature, it is easy to cause the accumulation of nitrite in crops under adverse conditions (forbidden to use in organic agriculture), which is a nitrate, which has certain safety hazards during storage and processing.
Effective application of potash
The effective application technology of potassium fertilizer is affected by many factors, among which soil type, fertility level, crop type and fertilization method have great influences.
Potassium
The degree of potassium deficiency in soil is a prerequisite for the effective application of potassium fertilizer. First, the effect of soil available potassium content on potassium fertilizer efficiency should be considered. The effect of potash fertilizer efficiency is closely related to soil available potassium abundance, that is, under other conditions, the lower the soil available potassium content, the better the potash fertilizer season.
Soil available potassium content less than 40 mg / kg is a soil that is extremely potassium deficient. Potassium has become a limiting factor for crop yield increase. It should be applied preferentially. The dosage per acre (K2O) is 5-10 kg, and potassium chloride or potassium sulfate is 10~. 20 kg, no matter what soil and crops, 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 the soil available potassium content is greater than 80 mg/kg, food crops may be applied less or not, except for some cash crops that are sensitive to potassium. At the same time, soil slow-acting potassium content, soil texture and ripening degree should be considered.
Soil slow-acting potassium can not be directly absorbed and utilized by crops. It is the source and reserve of soil available potassium. The lower the soil available potassium content, the lower the rate of conversion to available potassium. Fertilizer application of potassium fertilizer is often better. However, as a guide to the application of potassium in the season, the soil available potassium content is the main basis.
The coarse-grained sandy soil, due to the low potassium content, and the quick-dissolving potassium in the soil, is easy to be leached. The effect of applying potassium on this kind of soil is better than that of viscous soil, and the effect of increasing potassium fertilizer on soil with high degree of ripening. Generally not as good as the soil with low degree of ripening. Because the former contains more potassium, and has good soil physical and chemical properties, and has strong potassium supply capacity. The soil potassium content in southern China is low, and the application of potassium fertilizer should be concentrated in the south; however, the potassium deficiency area in the northern soil is gradually expanding, especially in some high-yield soils, and potassium deficiency is becoming more and more serious.
Potassium application
In the case of the same potassium deficiency in the soil, potash should be used preferentially on potassium-producing crops, in the order of potassium crops, legumes > potato, sugar beet, sugar cane, watermelon, fruit tree > cotton, hemp, tobacco > corn > Rice, wheat. Potassium-producing crops are relative. In the soil with severe potassium deficiency, the effect of potassium application is significant regardless of the crops. On potassium-rich soils, potassium fertilizers in potassium-producing crops often do not increase yield.
Different varieties of the same crop respond differently to potassium fertilizer. Taking rice as an example, the fertilizer efficiency of increasing potassium fertilizer in hybrid rice and dwarf stalk high-yielding pedigree rice is better than that of high stalk variety, japonica rice and conventional rice.
Soybeans, oilseeds, wheat, fruit trees, and rice crops can increase cold resistance and reduce freezing damage in a harsh environment such as cold, drought, and insufficient sunlight. The effect of increasing yield is very good. For example, black soil in northeastern China has higher soil available potassium and slow-acting potassium content. However, in recent years, tests on soybeans in black soil have shown that the application of potassium fertilizer in cold and dry years has the effect of enhancing soybean cold and drought resistance, and the fertilizer efficiency is also obvious.
Potassium application rate
The amount of potassium fertilizer also follows the phenomenon of diminishing returns. In the soil with potassium deficiency, the yield of crops increased with the increase of potassium application, and the increase of potassium per kg of potassium decreased with the increase of dosage. When the amount 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 elements. In the current situation of relatively low potassium fertilizer, it is generally not possible to fully meet the needs of crops, and it is appropriate to use 3 to 6 kg per mu of potassium fertilizer (K2O).
In the soil with potassium deficiency, generally 5 to 10 kg of rice can be produced per kilogram (K2O). The utilization rate of potash in the season is 40% to 50%. Crops with severe potassium deficiency and potassium in the soil, such as soybean, sweet potato, tobacco, sugar cane and other potash fertilizers can be appropriately increased, soil potassium deficiency is not serious and the amount of farmyard fertilizer is sufficient, potassium fertilizer can be applied less or not.
Potassium fertilizer application period
Potassium fertilizer can be used as base fertilizer, seed fertilizer or top dressing. Potassium fertilizer is the same as phosphate fertilizer. It is better to use base fertilizer or early topdressing because the seedling value of crops is the critical period of potassium and sensitive to potassium. Although the potassium intake in the seedling stage is less than 1% of the total growth period, the seedling stage is small and relatively large.
Potassium fertilizer application method
1 After plowing, plowing into the soil with a plow
2 when planting with or near the seed fertilization
3 After shallow application, shallow cultivation (squatting or polder)
4 hole application
5 surface application
6 foliar spray
(Agricultural Information)
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