Potassium fertilizers commonly used in production include potassium sulfate, potassium chloride and plant ash, and their main properties are shown in Table 9-3. The ashes left after burning plant residues are called plant ash. For a long time, straw, fallen leaves and dead branches have been used as fuel in most rural areas of China, so plant ash is an important source of fertilizer in agricultural production. The composition of plant ash is extremely complex, containing many ash elements in plants, among which potassium and calcium are more, followed by phosphorus, so it is usually regarded as potash fertilizer. In fact, it plays the nutritional role of many elements. The main form of potassium in plant ash is potassium carbonate, followed by potassium sulfate and potassium chloride. About 90% of potassium in plant ash is soluble in water, which is highly effective and is a quick-acting potash fertilizer. Because plant ash contains K2CO3, its aqueous solution is alkaline and it is an alkaline fertilizer. Due to different combustion temperatures, plant ash has different colors and potassium availability. When the combustion temperature is too high, potassium and silicic acid form low solubility K2SiO3, which is grayish white and has poor fertilizer efficiency. Plant ash, which burns at low temperature, is generally dark gray with high fertilizer efficiency.

2. Transformation of potash fertilizer in Trichosanthes kirilowii base soil

After potassium sulfate and potassium chloride were applied to the soil, potassium was in ionic state, one part was absorbed and utilized by plants, and the other part was adsorbed by colloid. In neutral and calcareous soils, Ca2+ is replaced to produce CaSO4 and CaCl2, respectively. CaSO4 _ 4 _ 4 is a slightly soluble substance, which can block pores and cause soil hardening after leaching with water for a certain distance. CaCl2 _ 2 _ 2 is water-soluble and easy to leach with water, which leads to the loss of Ca ~ (2+) and soil hardening. In arid and semi-arid areas, it will increase the content of water-soluble salts in soil. Therefore, the long-term application of potassium sulfate and potassium chloride in neutral and calcareous soils should be combined with the application of organic fertilizer. In acidic soil, both of them replace H+ to produce H2SO4 and HCl, which increases the acidity of acidic soil. Therefore, lime and organic fertilizer should be applied together.

3. Rational distribution and effective application of potassium fertilizer in Trichosanthes kirilowii base

The fertilizer efficiency of potassium fertilizer depends on soil properties, crop species, fertilizer combination, climate conditions and so on. Therefore, in order to allocate and apply potassium fertilizer economically and reasonably, it is necessary to understand the relevant conditions that affect the fertilizer efficiency of potassium fertilizer.

(1) Soil conditions and effective application of potassium fertilizer

Soil potassium supply level, soil mechanical composition and soil aeration are the main soil conditions that affect the fertilizer efficiency of potassium fertilizer.

Soil potassium supply level: the level of soil available potassium is an important factor to determine the fertilizer efficiency of potassium fertilizer, and the index value of available potassium varies slightly with soil, climate and crops. Through multi-point experiments in Liaoning Province, 90mg·∕·kg of available potassium (equivalent to K2O108 mg ∕ kg) was taken as the critical value of soil potassium abundance and deficiency. The content of available potassium is less than 90mg∕kg, and the effect of applying potassium fertilizer is remarkable; When the content of available potassium is 9 1mg∕kg- 150mg∕kg, the effect of applying potassium fertilizer is unstable, which depends on crop species, the content of available potassium in soil and the combination with other fertilizers. When the content of available potassium exceeds 150mg∕kg, potassium fertilizer is ineffective. It should be pointed out that it is not enough to judge the supply level of potassium only from the available potassium for the soil with the same low available potassium content and great difference in the slow-release potassium content, and the storage of slow-release potassium must be considered at the same time to estimate the supply level of potassium more accurately.

Mechanical composition of soil: The mechanical composition of soil is related to potassium content. Generally speaking, the finer the mechanical components, the higher the potassium content, and vice versa. Different soil textures will also affect soil potassium supply capacity, so some people put forward the critical indicators of potassium deficiency in different soil textures: K2O85mg∕kg is sandy soil-sandy loam, 100mg∕kg is sandy loam, and mg∕kg is clay. Therefore, the effect of applying potassium fertilizer on coarse sandy soil is higher than that of clay, and it is best to give priority to applying potassium fertilizer on sandy soil lacking potassium.

Soil aeration: Soil aeration mainly affects the absorption of potassium by affecting the respiration of plant roots, so that the soil itself is not deficient in potassium, but crops show symptoms of potassium deficiency. Therefore, in production practice, it is necessary to analyze the causes of potassium deficiency in crops in detail and take corresponding measures to improve the absorption of potassium by crops.

(2) Basic conditions of Trichosanthes kirilowii and effective application of potassium fertilizer.

Because of the different biological characteristics of different crops, their demand for potassium and their absorption capacity are also different, so their responses to potassium fertilizer are also different. Crops with high sugar content, such as Trichosanthes kirilowii, potatoes, sweet potatoes, sugar cane, beets, watermelons, fruit trees and tobacco, all need a lot of potassium. Therefore, more potassium should be applied to these potassium-loving crops, which can not only increase the yield, but also improve the quality. Under the same soil conditions, potassium-loving crops should be preferred. In addition, the application of potassium fertilizer on leguminous crops and oil crops also has obvious and stable yield-increasing effect. Of course, in the soil lacking potassium, potassium fertilizer has a good effect on many crops, but in the soil with moderate or abundant potassium fertilizer, only the crops that like potassium have better fertilizer efficiency.

(3) The fertilizer characteristics of Trichosanthes kirilowii and the effective application of potassium fertilizer.

Different types and properties of fertilizers have different application methods.

Potassium sulfate can be used as base fertilizer, topdressing, seed fertilizer and topdressing outside roots, while potassium chloride cannot be used as seed fertilizer. Potassium sulfate is suitable for all kinds of soils and crops, especially for crops that like potassium but avoid chlorine and crops that like sulfur, such as Cruciferae. Potassium chloride is suitable for fiber crops such as hemp and cotton, which can improve fiber content and quality. The application in paddy field can also prevent rice from black root, which is not suitable for chlorine-free crops and low-lying land and saline-alkali land with poor drainage.

Plant ash is suitable for base fertilizer, topdressing and seed mulching. When used as base fertilizer, it can be applied in ditches or holes with a depth of about 250px, and then covered with soil. When topdressing, it can be spread on the leaves, which can not only supplement nutrients, but also reduce or prevent the occurrence and harm of pests and diseases to a certain extent. Because plant ash is dark in color, contains a certain amount of carbon, absorbs heat quickly, and its texture is slack, so it is most suitable to be used as seed fertilizer for rice and vegetable seedlings, which not only supplies nutrients, but also helps to raise ground temperature and prevent rotten seedlings. Plant ash can also be used as topdressing outside the roots, with general crops 1% flooded, fruit trees 2%-3% flooded and wheat growing 5%- 10% flooded. Plant ash is an alkaline fertilizer, which can't be mixed with ammonium nitrogen fertilizer and decomposed organic fertilizer, and can't be stored in pigsty and toilet to avoid ammonia volatilization loss. Plant ash has a good response to a variety of crops on various soils, especially leguminous crops applied on acidic soils, and the yield increase effect is very obvious.

(4) Applying potassium fertilizer combined with nitrogen and phosphorus fertilizer in Trichosanthes kirilowii base.

Crops need a certain proportion of nitrogen, phosphorus and potassium, so the fertilizer efficiency of potassium fertilizer is related to the supply level of nitrogen and phosphorus. When the content of nitrogen and phosphorus in soil is low, the effect of applying potassium fertilizer alone is often not obvious. With the increase of nitrogen and phosphorus, the application of potassium fertilizer can increase the yield, and the interaction of nitrogen, phosphorus and potassium can also promote the absorption of potassium by crops and improve the utilization rate of potassium fertilizer.

(5) Potassium fertilizer application technology in Trichosanthes kirilowii base

Potassium fertilizer should be applied deeply and intensively: potassium is easily fixed by clay minerals in soil, especially 2∶ 1 clay minerals. Deep application of potassium fertilizer can reduce the lattice fixation caused by frequent alternation of wet and dry in this surface soil and improve the utilization rate of potassium fertilizer. Potassium is also an element with little fluidity in soil. Therefore, centralized application of potassium fertilizer can reduce the contact area between potassium and soil, reduce fixation, improve the diffusion rate of potassium, and be beneficial to the absorption of potassium by crops.

Potassium fertilizer should be applied early: usually, the proportion of potassium fertilizer as base fertilizer and seed fertilizer is large. If potash fertilizer is used for topdressing, it should be applied early. Because the key period of potassium nutrition in most crops is in the early stage of crop growth, potassium uptake by crops is intense in the middle and early stage, and it is obviously reduced in the later stage, and even some potassium overflows from the roots when it matures. Cereal crops need more potassium from tillering stage to jointing stage, accounting for 60%-70% of the total potassium requirement. Potassium is most needed in cotton, vegetable and eggplant, and radish fleshy root swelling. For perennial fruit trees, the suitable fertilization period should be selected according to the characteristics of fruit trees, such as pears in the developing stage and grapes in the early stage of berry coloring. In sandy soil, potassium fertilizer should not be applied in large quantities at one time, but should be applied in several times, that is, following the principle of small amount and multiple times to prevent potassium leaching. Clay can be used as base fertilizer at one time or in a large amount at one time.

Potassium fertilizer application amount: The application amount of potassium fertilizer depends on the available potassium content in the soil, the demand of crops for potassium and the balance among various nutrient elements. Generally, potassium oxide should be applied per mu, with 6 kg -9 kg of corn and 5 kg -8 kg of rice. For potassium-loving crops, it can be increased appropriately.

Four, trace element fertilizer

Trace element fertilizer refers to fertilizer containing trace elements such as boron, manganese, molybdenum, zinc, copper and iron. In recent years, the shortage of trace elements in agricultural production has become more and more serious, and many crops have been short of trace elements, such as corn and rice, fruit trees, rape and so on. The application of trace element fertilizer has achieved obvious yield-increasing effect and economic benefit, and the application of trace element fertilizer has been put on the agenda by the national agricultural department.

1. boron fertilizer

Main types and characteristics of boron fertilizer in Trichosanthes kirilowii base (1)

At present, boron fertilizers commonly used in production include borax, boric acid, calcium superphosphate containing boron, boron magnesium fertilizer and so on. Boric acid and borax are the most commonly used, and their main components and properties are shown in Table 9-4.

(2) Application of boron fertilizer in Trichosanthes kirilowii base.

Crop types and boron fertilizer application: Different crop types have different requirements for boron. At present, the crops with obvious boron deficiency in China are rape, beet, cotton, Chinese cabbage, cabbage, radish, celery, cucumber in greenhouse, soybean, apple, pear and peach. Corn, millet, potatoes, carrots, onions, peppers, peanuts, tomatoes, etc. Under the same soil conditions, priority should be given to these crops with high boron demand.

Soil conditions and boron fertilizer application: the content of water-soluble boron in soil is closely related to the fertilizer efficiency of boron fertilizer, which is an important basis for deciding whether to apply boron. According to the research of Oil Crops Research Institute of Chinese Academy of Agricultural Sciences, Shanghai Academy of Agricultural Sciences, Zhejiang Academy of Agricultural Sciences and other units, when the content of water-soluble boron in soil is less than 0.3mg∕kg, it is a serious boron deficiency, and when it is less than 0.5mg∕kg, the effect of applying boron fertilizer is obvious, so boron fertilizer should be given priority. The boron content in soil is also related to the application method of boron fertilizer. When the soil is seriously deficient in boron, the base fertilizer is better, and the soil with mild boron deficiency usually adopts the method of topdressing outside the roots.

Application technology of boron fertilizer: boron fertilizer can be used as base fertilizer, topdressing and seed fertilizer. When making base fertilizer, it can be used in combination with P and N fertilizers or applied alone. Generally, 0.25kg-0.5kg boric acid or borax should be applied every 667m2, and it must be applied evenly to prevent poisoning due to high concentration. Topdressing usually adopts the method of topdressing outside the roots, and the concentration of borax or boric acid solution is 0. 1%-0.2%, and the dosage is 50 kg-75 kg per 667m2, which is sprayed once at seedling stage and once when crops change from vegetative growth to reproductive growth. Seed dressing and soaking are often used as seed fertilizer. When soaking the seeds, soak the seeds with 0.0 1%-0. 1% boric acid or borax solution for 6- 12 hours, and then sow in the shade. 0.0 1%-0.03% solution can be used for cereals and vegetables, and 0. 1% solution can be used for rice. When dressing seeds, use 0.2-0.5g of borax or boric acid per kilogram of seeds.

2. Zinc fertilizer

Main types and characteristics of zinc fertilizer in Trichosanthes kirilowii base (1)

At present, zinc fertilizers commonly used in production include zinc sulfate, zinc chloride, zinc carbonate, zinc chelate, zinc oxide and so on. See Table 9-5 for its main components and properties.

(2) Application of zinc fertilizer in Trichosanthes kirilowii base.

Crop types and application of zinc fertilizer: Crops sensitive to zinc include corn, rice, sugar beet, flax, cotton, apples and pears. Applying zinc fertilizer to these crops usually has good fertilizer efficiency.

Soil conditions and application of zinc fertilizer: the content of available zinc in soil is closely related to the fertilizer efficiency of zinc fertilizer. According to the experiment of soil fertilizer station in Henan province, when the available zinc content in soil is less than 0.5 mg/kg, the application of zinc fertilizer to wheat, corn and rice has obvious yield-increasing effect. When the available zinc content in soil is between 0.5- 1.0mg/kg, the application of zinc fertilizer in calcareous soil and high-yield fields can still improve the yield and crop quality.

Application technology of zinc fertilizer: Zinc fertilizer can be used as base fertilizer, topdressing and seed fertilizer. Insoluble zinc fertilizer is usually used as base fertilizer. When used as base fertilizer, zinc sulfate can be mixed with physiological acid fertilizer at the rate of 1-2kg per 667m2. Apply it once every 1-2 years for the land with mild zinc deficiency, and reduce it every other year or next year for the land with moderate zinc deficiency. Topdressing is often used as topdressing outside the roots. The concentration of zinc sulfate solution for general crops is 0.02%-0. 1%, and that for corn and rice is 0. 1%-0.5%. Spraying 0.2% zinc sulfate solution at tillering stage, booting stage and flowering stage of rice; 5% zinc sulfate can be sprayed on fruit trees one month before germination, and 3%-4% concentration can be applied to fruit trees after germination; Spraying 0.2% zinc sulfate solution on annual branches for 2-3 times or in early summer. Seed fertilizer is often soaked or dressed. Seed soaking concentration is 0.02%-0. 1%, seed soaking 12 hours, and then sowing in the shade. Zinc sulfate is 2g-6g for seed dressing and 2g-4g for corn per kilogram. Zinc oxide can also be used as the root of rice seedlings, with the dosage of 200 g per 667 m2, and made into 1% suspension concentrate.

The relationship between zinc fertilizer and phosphorus fertilizer efficiency: induced zinc deficiency mostly occurs in soils with high available phosphorus content, for example, some paddy soils lack zinc because of high available phosphorus content. One reason is the antagonism of phosphorus and zinc, and the other reason is the increase of P2O5∕Zn in plants. In order to maintain normal P2O5∕Zn, crops need to absorb more zinc. When applying phosphate fertilizer, we must pay attention to the nutrient supply of zinc fertilizer to prevent zinc deficiency caused by excessive phosphorus.

3. Manganese fertilizer

Main types and characteristics of manganese fertilizer in Trichosanthes kirilowii base (1)

Manganese fertilizers commonly used in production include manganese sulfate and manganese chloride, and their main components and properties are shown in Table 9-6.

(2) Application of manganese fertilizer in Trichosanthes kirilowii base.

Crop types and fertilizer efficiency of manganese: crops sensitive to manganese include beans, wheat, potatoes, onions, spinach, apples and strawberries. , followed by barley, sugar beet, clover, celery, radish, tomato and so on. Crops insensitive to manganese are corn, rye and pasture.

Soil conditions and application of manganese fertilizer: Generally, the active manganese content is used as the main index to diagnose the manganese supply capacity of soil. The content of active manganese in soil is extremely low, and the content of 50 mg ∕ kg-100 mg ∕ kg-200 mg ∕ kg is low. The application of manganese fertilizer in manganese-deficient soil has a good yield-increasing effect on general crops.

Application technology of manganese fertilizer: the most commonly used manganese fertilizer in production is manganese sulfate, which is generally used as topdressing outside roots, soaking seeds, dressing seeds and soil seed fertilizer, and insoluble manganese fertilizer is generally used as base fertilizer. Generally, 0.05%-0. 1% is suitable for topdressing outside roots, 0.3%-0.4% for fruit trees, 0.03% for leguminous crops and 0. 1% for rice. Seed dressing: Gramineae crops use 4 grams of manganese sulfate per kilogram of seeds, leguminous crops use 8g- 12g, and sugar beets use 0/6 g; The effect of manganese sulfate as soil seed fertilizer is similar to that of seed dressing, and the general dosage is 2kg∕667m2-4kg∕667m2.

4. Iron fertilizer

Main types and characteristics of iron fertilizer in Trichosanthes kirilowii base (1)

See Table 9-7 for the types, components and properties of iron fertilizers commonly used in production.

(2) Application of iron fertilizer in Trichosanthes kirilowii base

Crop types and iron fertilizer efficiency: The crops sensitive to iron include soybean, sorghum, beet, spinach, tomato and apple. Generally speaking, iron deficiency is rare in Gramineae and other crops, but it is more common in fruit trees. In addition, some acidic flowers in the south, such as gardenia and camellia, are also quite common when planted in the north.

Application technology of iron fertilizer: ferrous sulfate is the most commonly used iron fertilizer in production, and it is mostly applied by topdressing outside the roots at present. The spraying concentration is 0.2%- 1%. Most fruit trees were sprayed with 0.75%- 1% ferrous sulfate before germination or sprayed with 0.5% ferrous sulfate and 0.5% urea three times after yellow leaves. You can also mix ferrous sulfate with organic fertilizer at the ratio of 1: 10-20 and apply it to fruit trees, each plant is 50 kg, and the fertilizer effect can last for one year, so that 70% of iron deficiency can be restored to green. High-pressure injection is also an effective method of applying iron to fruit trees, that is, 0.3%-0.5% ferrous sulfate solution is directly injected into the xylem of the trunk, and then transported to the needed parts with the liquid flow. In addition, according to the research of Liu Zangzhen of Hebei Agricultural University, when the fruit trees are yellow due to iron deficiency, the diseased leaves only turn green in spots, and the new leaves are still yellow, and the effect is not good. If urea and citric acid are added to the iron fertilizer solution, the effect will be very good. The preparation method of the solution is as follows: firstly, 25g of citric acid is added into 50kg of water, then 125g of ferrous sulfate is added after dissolution, and 50g of urea is added after dissolution of ferrous sulfate, so as to obtain the composite iron fertilizer of 0.25% ferrous sulfate +0.05% citric acid +0. 1% urea.

5. Molybdenum fertilizer

Main types and characteristics of molybdenum fertilizer in Trichosanthes kirilowii base (1)

Commonly used molybdenum fertilizers in production include ammonium molybdate, sodium molybdate, molybdenum trioxide, molybdenum slag, molybdenum-containing glass fertilizer and so on. See Table 9-8 for its main components and properties.

(2) Application of molybdenum fertilizer in Trichosanthes kirilowii base.

Response of crop varieties to molybdenum fertilizer: Leguminous crops lack molybdenum, alfalfa is the most prominent, and rape, cauliflower, corn, sorghum, millet, cotton and beet also have good responses to molybdenum fertilizer.

Soil conditions and application of molybdenum fertilizer: the application effect of molybdenum fertilizer is related to the content, form and distribution area of molybdenum in soil. Liu Kun, Nanjing Institute of Soil Research, Chinese Academy of Sciences, divided the molybdenum content and fertilizer efficiency in China into three regions, namely, significant region, effective region and possible effective region. Crops needing molybdenum fertilizer in the significant area of soil molybdenum fertilizer in the north are soybeans and peanuts, while crops needing molybdenum fertilizer in the significant area of soil molybdenum fertilizer in the south are leguminous green manure, peanuts, soybeans, citrus and so on. Crops that need molybdenum fertilizer in the effective area of molybdenum fertilizer include leguminous green manure, peanuts, soybeans and so on. However, the application of molybdenum fertilizer in the possible effective area of molybdenum fertilizer needs further experimental study.

Application technology of molybdenum fertilizer: molybdenum fertilizer is mostly used as seed fertilizer (seed dressing and soaking) and topdressing outside the roots. During seed dressing, 2g-6g of ammonium molybdate is used for each kilogram of seeds, which is first dissolved in hot water, then diluted into 2-3% solution with cold water, sprayed on the seeds with a sprayer and mixed while spraying. After mixing, the seeds are dried in the shade and can be planted. When soaking seeds, 0.05%-0. 1% ammonium molybdate solution can be used for soaking seeds 12 hours. Foliage fertilizer is generally used for crops with large leaf area. Spraying 0.0 1%-0. 1% ammonium molybdate solution 1-2 times in seedling stage and bud stage, and spraying 50 times every 667m2.

6. Copper fertilizer

Main types and characteristics of copper fertilizer used in Trichosanthes kirilowii base (1)

Common copper fertilizers in production include copper sulfate, copper smelting slag, chelated copper and copper oxide, and their main components and properties are shown in Table 9-9.

(2) Application of copper fertilizer in Trichosanthes kirilowii base

Crop types and fertilizer efficiency of copper: Different crops have different reactions to copper. Studies show that the crops that need more copper are wheat, onion, spinach, alfalfa, sunflower, carrot, barley and oats. There are beets, flax, cucumbers, radishes, tomatoes and so on. Medium copper is required; There are also beans, pasture, rape and so on that need less copper. There are also reports that apples, peaches and strawberries in fruit trees lack copper.

Soil conditions and copper fertilizer application: China's soil copper content is relatively rich, generally above 1mg/kg. The content of available copper in red soil developed on red sandstone in hilly area of Central China, sandy yellow fluvo-aquic soil in Xuhuai area of Jiangsu, aeolian sand in northwest China and loessial soil is low, and the effect of applying copper fertilizer is better.

Application method of copper fertilizer: copper fertilizer can be used as base fertilizer, topdressing and seed treatment. The dosage of copper sulfate as base fertilizer is 667 m2 1kg- 1.5kg. Because of the long period of validity of copper fertilizer, it is advisable to apply it once every 3-5 years to prevent the toxic effect of copper. Topdressing is usually based on topdressing outside roots, and the spraying concentration is 0.02%-0.04% for fruit trees and 0.2%-0.4% for fruit trees, and 10%-20% hydrated lime containing copper sulfate is added to prevent phytotoxicity. The dosage of copper sulfate seed dressing agent is 0.3g-0.6g∕kg, and the seed concentration is 0.0 1%-0.05% copper sulfate solution.

7. Problems needing attention in applying microelement fertilizer in Trichosanthes kirilowii field

Pay attention to the application amount and concentration: the demand for trace elements in crops is very small, and the range from moderate to excessive is very narrow. It is necessary to prevent excessive use of trace elements. When applying soil, it must be evenly applied and the concentration should be appropriate, otherwise it will cause plant poisoning, pollute soil and environment, and even enter the food chain, which will hinder the health of people and animals.

Pay attention to improving soil environmental conditions: the lack of trace elements is often not because of the low content of trace elements in soil, but because of its low effectiveness. By adjusting soil conditions such as pH, redox, soil texture, organic matter content and soil water content, the nutritional status of trace elements in soil can be effectively improved.

Pay attention to the combined application with macro-element fertilizers: trace elements are as important as nitrogen, phosphorus, potassium and other nutrients and cannot be replaced. Only when the demand of plants for macroelements is met, the application of trace fertilizer can give full play to its fertilizer efficiency and show obvious yield-increasing effect.