In recent years, fertilization combined with irrigation has been widely used in protected areas. Fertilization with water has the advantages of synchronizing water and fertilizer, reducing the volatilization of fertility, improving fertilizer utilization and labor saving. We will mainly introduce the fertilizer characteristics, fertilization amount and irrigation and fertilization methods of crops in protected areas.
(-) Protected ground irrigation and fertilization method
1. Fertilization methods in protected areas Overview Fertilization methods for crops in protected areas usually include soil fertilization, topdressing and root dressing. The various methods and requirements are briefly described as follows:
(1) Soil fertilization Soil fertilization is a fertilization method in which the fertilizer is applied to the root distribution layer according to the distribution characteristics of the root system. This method is convenient for the root system to absorb and exert the maximum effect of the fertilizer. In the case of fruit trees, their horizontal roots are generally concentrated farther outside the canopy. The root system has a fattening property, and its growth direction is often transferred by the fertilization site. Therefore, organic fertilizer is generally applied slightly deeper and farther away from the root distribution layer, and the root system is induced to grow deeper and deeper, forming a strong root system, expanding the absorption area, improving root absorption efficiency and tree nutrient level, and enhancing the stress resistance of the fruit tree. . The depth and breadth of fertilization are related to tree species, variety, age, rootstock, soil and fertilizer types. The fertilization method of fruit trees generally includes ring fertilization. Fertilization in the ditch, fertilization and fertilization in the whole garden. The fertilization methods of vegetables generally have two methods: base fertilizer and topdressing. The base fertilizer is a method of applying soil fertilizer to the soil before and after planting, and it is the nutrient basis for high-quality and high-yield vegetables. The base fertilizer should be based on organic fertilizer. The application method of organic fertilizer usually depends on the degree and degree of decomposing of organic fertilizer, and the organic fertilizer with poor maturity and large amount is not suitable for concentrated ditch application. It should be removed from the surface and combined with cultivated land into the soil; The better and lesser amount of organic fertilizer should be concentrated in the ditch. If the amount is too large, it can be used for ditching and half for spreading. It not only meets the nutrient requirements of vegetables, but also achieves the purpose of fertilizing the soil. When applying a hole, it is necessary to use the decomposed organic fertilizer, and it should not be applied too much to avoid causing the burning of the seedlings. When the hole is applied, the fertilizer and the soil should be evenly mixed.
(2) Topdressing Fertilizer applied in the vegetable seedling stage or after planting is called top dressing. Generally, quick-acting fertilizers are mainly used, among which nitrogen fertilizer is the main, and potassium fertilizer is the second; topdressing should be applied according to different growth and development stages of vegetables, and the principle of less application and diligence should be adopted. The number of top dressings can be determined according to the length of the growing period of vegetables. Vegetables with short growth period can be used for 1 to 3 times in the middle of growth. Vegetables with long growing period can be used for 3 to 5 times in the period of more nutrient demand. frequency. Generally, the fat is chased once every 15 to 20 days. If the amount of topdressing is too large, not only can the vegetables not be absorbed, but also the burning of seedlings and waste, and the soil salt concentration is too high, which hinders the growth of vegetable roots.
(3) Top dressing is also called foliar spray fertilizer. This method is simple and easy. It can improve the photosynthesis and enzyme activity of leaves, thus improving root nutrition, promoting root development, enhancing absorption capacity and promoting overall plant metabolism. process. The use of small amount of fertilizer, quick effect, and not affected by the nutrient distribution center, can meet the crop requirements in time and avoid the loss or fixation of certain elements in the soil. But root dressing is not a substitute for soil fertilization. Both have their own characteristics, complement each other, and use them properly to exert the maximum effect of fertilization.
2. Several kinds of irrigation and fertilization methods commonly used in protected areas have been widely used in protected areas in recent years. The soil fertilization methods in protected areas can generally be combined with various irrigation methods such as gully irrigation, sprinkler irrigation, drip irrigation and seepage irrigation.
(1) The method of fertigation combined with gully irrigation is generally to set up various fertilization facilities at the head end of the field, such as fertilization ponds, etc. Sometimes, a small pit can be dug in the field, plastic film is placed instead, and various fertilizers are placed. After entering the pool and dissolving it, it flows into the field with water and enters the root layer of the crop. In the protected area for fertilization of alfalfa, the following issues should be noted:
1 The concentration of the fertilization solution is strictly controlled between 0.2% and 0.3%;
2 must pay attention to the fertilization period in the irrigation.
(2) Irrigation fertilization method combined with drip irrigation This method is partially irrigated. Local fertilization, water and fertilizer efficiency is higher, while the fertilization concentration can be adjusted, relatively safe, and has the effect of effectively reducing the air humidity of the protected area and preventing the spread of pests and diseases. In drip fertigation, it is generally achieved by adding a fertilizing device in the system. Commonly used fertilization (pesticide) devices include differential pressure fertilization tanks, open fertilizer tanks, venturi fertilisers, and injection pumps. The structure of various common fertilization devices is as follows:
1 Differential pressure fertilization tank: The differential pressure fertilization tank consists of a liquid storage tank, an inlet pipe, a water pipe and a pressure regulating valve, as shown in Figure 5-4.
The pressure difference type fertilization tank fertilization operation process is: after the normal operation of the watering system, the soluble fertilizer or fertilizer solution is first injected into the liquid storage tank 1, and then the can lid is closed; the valve 6 is opened to open the fertilizer supply tube 7 and then opened. Valve 4, and the inlet pipe 2 is turned on, at this time, the pressure of the liquid storage tank and the water delivery pipe are balanced. Then, the small fertilizer pressure regulating valve 5 is closed, so that the pressure difference in the water pipeline before and after the valve is generated, so that the fertilizer in the tank under the pressure, through the fertilizer pipeline into the valve, the water storage tank also causes the liquid storage tank The internal pressure is reduced. This cycle is repeated until the fertilizer in the tank is finished, and new fertilizer is added. The advantage of the differential pressure fertilization tank is that it is simple to manufacture and manufacture, and the cost is low, and no additional power equipment is needed. The disadvantage is that the concentration of the fertilizer solution varies greatly and cannot be controlled. The volume of the tank solution is limited, and the number of added fertilizers is frequent.
3 Open fertilizer tank self-pressure fertilization device: In the self-pressure irrigation system, it is very convenient to use open fertilizer tank or build a fertilizer tank. Simply place the fertilizer tank in the proper position under the self-pressing water source, connect the fertilizer water supply pipe to the water source through the control valve, connect the infusion pipe and the valve to the main pipe of the irrigation system, and open the fertilizer supply valve according to the required opening degree. Fertilize. Open fertilizer tanks are commonly used in single shed independent irrigation systems or in self-pressure irrigation systems.
3 Venturi Fertilizer Injector: The Venturi Fertilizer Injector can be used in conjunction with an open fertilizer tank to form a fertilizing device. The utility model has the advantages of simple structure, convenient use and low cost. Mainly used as a fertilizing device for small irrigation systems. The structure of the Venturi fertilizer injector is shown in Figure 5-6. The disadvantage is that if it is directly connected to the main pipe, it will cause a large pressure loss.
4 Infusion pump: In the irrigation system, a piston pump or a diaphragm pump is often used to inject fertilizer solution or pesticide into the irrigation pipeline. According to the power source of the driving water pump, it can be divided into two types: hydraulic drive and mechanical drive. Figure 5-6 shows the piston type fertilizer pump, and Figure 5-7 shows the hydraulic fertilizer pump. The advantage of using this type of device is that the fertilizing device can uniformly supply fertilizer to the irrigation water source, thereby ensuring that the concentration of the fertilizer water is stable, the fertilization quality is good, and the efficiency is high; the disadvantage is that additional power equipment and injection pump are needed, so the cost is higher. high.
In order to ensure that the irrigation system fertilization (application) device operates normally during fertilization (application) and that the irrigation water source is not contaminated, the irrigation system does not work properly due to fertilization (application), and the irrigation system applies fertilizer (application) The following points should be noted when using the device: The application device for fertilizer and pesticide should be installed between the water source and the filter, so as to ensure that the fully dissolved fertilizer or pesticide neither pollutes the water source and can be filtered after entering the subsequent irrigation. The system ensures that undissolved fertilizers and other impurities will not enter the water trap and avoid clogging of the emitter and its piping.
(b) After fertilizing or applying pesticides, be sure to leave residual pesticides or fertilizers in the irrigation system or fertilizing device. Therefore, after fertilization and application, rinse the residue left in the fertilizer tank or pesticide application device with clean water to prevent the fertilization, application device and pipeline from being corroded.
(c) A check valve should be installed between the fertilizer or pesticide application device and the water source to prevent the dissolved fertilizer or liquid from flowing into the water source and contaminating the water source. In particular, it should be noted that chemical fertilizers or pesticides cannot be directly added to water sources to prevent pollution of water sources and even the environment caused by chemical fertilizers or pesticides.
(d) Fertilizer and application device When applying different fertilizers and pesticides in different growth stages of crops, it is necessary to make the applied fertilizers both uniform and safe. Therefore, it must be completed according to certain operating procedures. If the spraying task of foliar fertilizer is finally completed by using the micro sprinkler irrigation system, the irrigation should be carried out first, and then the fertilizer or pesticide should be applied when the irrigation quota is close, and the amount and time of flushing the fertilization and application device should be reserved.
(3) Irrigation and fertilization methods combined with sprinkler irrigation, micro-sprinkler irrigation and fog irrigation can be combined with sprinkler irrigation, micro-sprinkler irrigation, and fog irrigation to carry out soil fertilization or root dressing, which is characterized by external fertilization. For convenience, the effect is very good. Its fertilization device is similar to irrigation. When spraying foliar application, pay attention to the type of fertilizer applied. Only water-soluble fertilizer and organic fertilizer leaching solution can be sprayed with foliar surface, and attention should be paid to the concentration of spraying. If the concentration is too high, it will cause burning. seedling. Foliar fertilization, in addition to a large number of commonly used elements and trace elements such as urea, potassium dihydrogen phosphate, potassium sulfate, potassium nitrate, compound fertilizer, etc., at present, many manufacturers have developed a large number of elements and trace amounts suitable for crop foliar application. Elements, or fertilizers containing a variety of amino acids, have a certain effect. A small amount of neutral detergent should be added when spraying a large amount of elemental fertilizer to increase the adhesion and improve the effect of spraying fertilizer.
Foliar application of phosphorus and potassium fertilizer should be used in the young fruit stage of cloth and melon vegetables to promote fruit expansion; legumes and leafy vegetables can be used in addition to phosphorus and potassium fertilizer in the growing season. Spraying borax during breeding to the beginning of flowering can increase seed yield.
Foliar application of fertilizer is required to be carried out on a windless sunny day. It is best to spray it after 4 pm in the daytime. In the greenhouse, the shed can be sprayed in time after the dew is dropped. The spraying frequency of foliar fertilization is generally 2 to 3 times. It can also be determined according to the condition of vegetable deficiency and the speed of nutrient running in vegetables. For example, nitrogen and potassium nutrients can run fast, and the number of spraying can be less. Spraying 1 or 2 times during the growth period or critical period; the transfer rate of phosphorus is slow, and it can be sprayed 2 to 3 times. The trace elements are extremely weak in the vegetable body and can be sprayed 3 to 4 times. The type, concentration, period and frequency of fertilizer applied to foliar application.
At present, various irrigation and fertilization methods are mutually infiltrated and supplemented, for example, soilless cultivation of vegetables using nutrient solution is an example. Because it does not use soil, fertilizer and water recycling, no pesticide pollution, it is attracting attention as a means of production of vegetables. This kind of water supply and fertilizer can not only produce celery, lettuce, duck celery, shallots and other leafy vegetables, but also can produce tomato, cucumber, strawberry and melon and other fruits and vegetables, and its cultivation range is still expanding. The appropriate concentration of urea sprayed on its foliage.
There are many ways to cultivate nutrient solution, and Figures 5-8 are schematic diagrams of one way.
(II) Fertilizer characteristics of vegetables Irrigation is not only a measure for supplying water to vegetables, but also a means of fertilizing vegetables. Although China's vegetable cultivation has rich and unique experience in using organic fertilizer combined with traditional surface irrigation methods, it has only been nearly 30 years in the application of chemical fertilizer combined with irrigation. There are still many problems to be solved. This section attempts to provide a basis for rational fertilization and irrigation through the preliminary induction of scientific research results in this area in recent years, so as to achieve high-quality, high-yield and high-efficiency production purposes.
1. The average nitrogen uptake of vegetables in vegetables requires fertilizers and fertilizers to be 0.4 times higher than wheat, 0.2 times higher in phosphorus uptake, 4.3 times higher in calcium absorption, and 0.54 times higher in magnesium absorption. At the same time, vegetable fertilizer requires the following characteristics:
(1) Different vegetable varieties require different types of vegetables. Different types of vegetables absorb different amounts of nutrients in the soil, which depends mainly on the absorption capacity, yield, growth period, growth rate and other ecological conditions of the root system. In general, vegetables with deep roots, wide branches, and root hairs have large contact points between roots and soils, and can absorb more nutrients; the nutrient elements of vegetables with shallow roots and small distribution range are small. For example, carrot roots are 3 to 4 times longer than onion roots, and the lateral growth range is doubled, and the area for nutrient absorption is 19 times larger. Therefore, the roots of carrots are much more absorbent than onions. At the same time, vegetables with high yields absorb more nutrients. In the same vegetable, when the yield level is increased, the amount of nutrients absorbed from the soil per unit area also increases, and the amount of mineral nutrients required per unit of production is relatively reduced. Therefore, the higher the yield per unit area, the greater the yield increase benefit of fertilizer.
Different types of vegetables have different growth periods and growth rates. The total amount of general fertilizer is long in the growing period; the amount of fertilizer absorbed in the general unit of time is high, and the fertilization should be guided by the strength of the fertilizer, and the total amount of the fertilizer is also referred to.
Due to phylogenetic and genetic reasons, the total amount of nutrients in the soil absorbed by different vegetables is different. According to this, vegetable crops can be divided into the following four categories:
1 large absorption, such as cabbage, Chinese cabbage, carrots, beets, potatoes, etc.;
2 medium absorption, such as tomato, eggplant, etc.;
3 absorption is small, such as spinach, celery, knotted lettuce, etc.;
4 absorption is very small, such as cucumber, water radish.
The ability of different types of vegetables to utilize mineral nutrients is also different. For example, cabbage can use nitrogen most. Beet can use phosphorus most. The demand for three elements is large. The ability of tomato to use phosphorus is the weakest, but it has no adverse reaction to a large amount of phosphorus. Therefore, understanding the fertilizer characteristics of different vegetables and fertilizing as needed can improve the fertilization effect.
Different varieties of the same vegetable require different fertilizers. The sorghum tolerance and fertility of the cultivar are determined by genetics. Early-maturing cultivars generally have a fast growth rate and a large amount of fertilizer per unit time, but the growth is short and the total amount of fertilizer is small. Therefore, it is necessary to apply quick-acting fertilizers; late-maturing varieties generally require a large amount of fertilizer and a long growth period. In addition to the need to re-apply the base fertilizer, it is necessary to apply multiple times and apply long-acting fertilizer early.
(2) Different fertilizers in the same growth period require different fertilizers. In terms of the whole development period of vegetables, the growth of seedlings is small and the nutrient elements are less. For example, the absorption of nutrients in cabbage seedlings is only 1/5 to 1/6 of that of adult plants, but the relative growth rate in seedling stage is fast, requiring full and large amounts of fertilizer components. As the plants grow, the amount of fertilizer is gradually increased. When the product organ is formed, the growth amount reaches the peak value and the fertilizer amount is also the most. Generally, the ability of the adult plant to bear the concentration of the soil solution is 2 to 2.5 times larger than that of the seedling.
The requirements for fertilizer types in different growth stages of vegetables are also different. Generally, nitrogen is needed in the whole growth period, especially leafy vegetables. When the supply of nitrogen fertilizer is sufficient, the vegetative growth is good, the chlorophyll content in stems and leaves is high, the leaves are dark and the functional period is long. Phosphorus is also needed in the whole growth stage, especially in the seedling stage of fruit and vegetable, the amount of flower bud differentiation has a good effect on increasing the quantity and quality of flower bud differentiation. (3) Different types of vegetables and vegetables require different types and types of vegetables. Different vegetables and organs have different fertilizer characteristics. Leafy vegetables generally require more nitrogen. Multiple nitrogen fertilizers are beneficial to increase yield and improve quality. Phosphorus and potassium are more abundant. The application of phosphorus and potassium fertilizers is conducive to the expansion of its product organs; the needs of the three elements of fruit and vegetables are relatively balanced, especially in the fruit formation period.
Different types of leafy vegetables require different fertilizers. Green leafy vegetables require the most nitrogen during the whole growth period, and fast-acting nitrogen should be used. Although the leaves and leaves need more nitrogen, it is mainly in the seedling stage and the initial stage of the rosette. When entering the vigorous growth period, it is necessary to increase the application of phosphate fertilizer and potassium fertilizer. When the phosphorus and potassium are insufficient, it is not easy to form a ball. Roots and stems still need a lot of nitrogen fertilizer in the seedling stage, and need a proper amount of phosphate fertilizer and a small amount of potassium fertilizer. When the roots and stems are swollen, a large amount of potassium, an appropriate amount of phosphorus and less nitrogen are needed. If there is too much nitrogen in the whole growth period and the supply of potassium is insufficient, the upper part of the plant is prone to be long, and the fleshy roots, roots, tubers, rhizomes, bulbs, etc., which are product organs, cannot be fully expanded because they do not have sufficient nutrients. If the nitrogen fertilizer is insufficient in the early stage, the growth is slow, the area of ​​the functional leaves (the rosette leaves) is small, and the development is slow, so that when the roots and stems are swollen, the nutrient supply is insufficient and the yield is low. Fruit and vegetable require more nitrogen and phosphorus in the seedling stage. The relative absorption of potassium is less. After entering the reproductive growth period, the demand for phosphorus increased sharply, while the absorption of nitrogen decreased slightly. If there is too much nitrogen in the later stage and the phosphorus is insufficient, the stems and leaves are long and affect the result. In the early stage, when the nitrogen is insufficient, the plants are small, and when the phosphorus and potassium are insufficient, the flowering period is postponed, and the yield and quality are also reduced. In addition, vegetables have different requirements on the form of soil nutrient elements. Mineral elements have their own forms, such as nitrogen with hinged nitrogen, nitrate nitrogen, urea nitrogen, phosphorus with phosphoric acid, and phosphate rock.
At the same time, the amount of boron in vegetables is much higher than that of gramineous plants, so the amount of boron required is also high.
2. The amount of fertilization of vegetables is determined to meet the requirements of nutrients for vegetable growth and development, and to achieve economic and rational fertilization and irrigation, the types and dosages of fertilizers should be determined according to external conditions such as soil nutrient requirements and soil fertility levels. Period and fertilization methods. (1) Nutritional diagnosis method of vegetable plants The nutrient content of various vegetables in different growth stages is different. It can be used to guide rational fertilization irrigation by diagnosing whether it is sufficient. The sampling time, location and standard of main vegetable plants are listed in Table 5- 11.
(2) Soil fertilization method According to the difference between the fertility element requirements of different types of vegetables and the local soil fertility elements, the amount of fertilization of vegetables is determined. The calculation formula is as follows:
Fertilizer dosage = (requires element amount - soil element content - organic fertilizer dosage × organic fertilizer content factor × organic fertilizer utilization coefficient) / (fertilizer element content × fertilizer utilization coefficient)
In the formula, the amount of elements required for various vegetables is determined, and the amount of soil elements can be obtained according to local soil fertility. The nutrient content of organic fertilizer is shown in Table 5-13; the utilization rate of different fertilizers under different external conditions is generally: organic Fertilizer (for base fertilizer) is 20% to 30%, nitrogen and potassium in fertilizer are 50% to 70%, and phosphate fertilizer is 20% to 40%.
(3) Determination of the amount of fertilizer applied to the vegetable field. In addition to considering the soil fertility status and the nutrient uptake of the vegetables, attention should also be paid to the yield of the vegetables and the quality of the fertilizer.
When fertilizing, take care to prevent high salt damage caused by excessive use. For example, cucumber is a medium salt-tolerant vegetable. When the salt content in the soil reaches 0.2% to 0.3%, its growth is severely inhibited, and the yield is reduced by 1/2. The amount of one application should generally not exceed 2/3 of the maximum limit. In particular, care should be taken when applying ammonium chloride and potassium chloride, as chlorinated salts have the most significant effect on increasing the concentration of soil solutions. When there is no data, the proportion of fertilization and the number and number of top dressings of vegetables are shown in Table 5-12 and Table 5-14.
(3) Calculation of fertilizer characteristics and fertilization amount of fruit trees
1. Fertilization characteristics of fruit trees The demand for fertilizer in fruit trees varies with the growth of tree age, the increase in the amount of results, and changes in environmental conditions. Generally, citrus fruit trees require a large amount of fertilizer, which is often twice as much as apples per year; apples, grapes, etc. are more tree species in deciduous fruit trees. At the same time, the amount of fertilizer required for the same species of fruit trees is not the same. For example, rosin and green banana apples are usually applied twice as much as other varieties to produce good results. Even for the same variety, the nutrient content and growth of the tree are different because of different nutrient and fertilizer supply conditions. Such as Bayun pear, rootstock, etc., the content of nitrogen and phosphorus in the leaves is high, and the growth of new shoots is large. Therefore, the amount of fertilization should be appropriately increased or decreased according to different rootstocks in order to make the tree healthy and productive. The fertilization of fruit trees varies with the growth stage of fruit trees. Generally, saplings and saplings need less fertilizer, which can be appropriately applied; trees with large trees and many results should be applied appropriately.
The excessive or insufficient amount of fruit trees has adverse effects on the growth and development of fruit trees. According to the report of the Liaoning Provincial Institute of Agricultural Sciences (1971), the amount of fertilizer absorbed by fruit trees increased with the increase of fertilizer application within a certain range; when the amount exceeded, the amount of fertilizer increased decreased. The absorption of 0.35 kg of nitrogen was the highest, while the difference of 0.6 kg or more with the plant was 0.25 kg, which indicated that the excessive application of fruit trees could not be absorbed.
2. Method for determining the amount of fertilizer applied
(1) Summarizing the experience of mass fertilization People in the fruit areas of China have accumulated valuable experience in fertilization in long-term production practice. Therefore, extensive investigations were carried out on the types and quantities of fertilization in local orchards, and comprehensive analysis and analysis of tree potential, yield and quality of different orchards were carried out, and the effects of fertilization were summarized to determine the amount of fertilization that could ensure the tree potential and obtain early fruit and high yield. And in the production practice combined with the results of tree growth results, and constantly adjust, so that the amount of fertilizer is more in line with the requirements of fruit trees, is an effective method, simple and practical, strong practical.
(2) Field Fertilizer Test Field fertilizer tests were conducted on different tree species and varieties by region, and the amount of fertilizer was determined based on the test results. The method is reliable and easy to use. According to the survey data, the ratio of nitrogen, phosphorus and potassium should be paid attention to when fertilizing common fruit trees, see Table 5-15.
(3) Leaf analysis The leaves of fruit trees can generally reflect the nutritional status of trees in a timely and accurate manner. Analysis of the leaves, can find the symptoms that are invisible to the naked eye, analyze the lack or excess of various nutrient elements, determine the type and quantity of fertilizers suitable for application, the method is more reliable, and can give the deficiency status of fruit trees in time. To ensure the normal growth and results of fruit trees. This method has been applied more and more widely in recent years.
For leaf analysis, the leaves are harvested directly when the leaf nutrient changes are small. For deciduous fruit trees, it is advisable to pick the leaves after germination and when the growth is stopped, and the storage status of the tree in the first year and the accumulation level of the year can be measured. Citrus fruit trees adopt leaves with leaf ages from May to July, and also reduce sampling errors. Generally, they represent 5 to 10 fruit trees, and generally do not produce spring shoots with a total of 100 to 200 tablets.
The nutrient content of leaves often varies with tree species, variety, age, rootstock and area. The leaves of citrus, apple and peach have higher nitrogen content; the same species have different varieties.
3. Calculation of fertilization amount (calculation of theoretical fertilization amount) Before calculating the fertilization amount, it is necessary to measure the amount of nutrients absorbed by the fruit preparation organs from the soil every year (Table 5-16), deducting the energy supply in the soil, and then considering the loss of fertilizer. The difference is the amount of fertilizer applied.
The following formula can be used in the calculation:
Fertilization amount = (amount of fertilizer absorbed by fruit trees - soil supply) / fertilizer utilization
In the formula, fruit nutrient fertilizers are given in Tables 5-15. The soil supply can generally be 1/3 of the absorption of nitrogen, 30% of phosphorus, and 40% of potassium. Due to the application of liquid fertilizer and irrigation, the fertilizer utilization can be significantly improved. The rate of fertilizer utilization mentioned above can be appropriately increased.
(-) Protected ground irrigation and fertilization method
1. Fertilization methods in protected areas Overview Fertilization methods for crops in protected areas usually include soil fertilization, topdressing and root dressing. The various methods and requirements are briefly described as follows:
(1) Soil fertilization Soil fertilization is a fertilization method in which the fertilizer is applied to the root distribution layer according to the distribution characteristics of the root system. This method is convenient for the root system to absorb and exert the maximum effect of the fertilizer. In the case of fruit trees, their horizontal roots are generally concentrated farther outside the canopy. The root system has a fattening property, and its growth direction is often transferred by the fertilization site. Therefore, organic fertilizer is generally applied slightly deeper and farther away from the root distribution layer, and the root system is induced to grow deeper and deeper, forming a strong root system, expanding the absorption area, improving root absorption efficiency and tree nutrient level, and enhancing the stress resistance of the fruit tree. . The depth and breadth of fertilization are related to tree species, variety, age, rootstock, soil and fertilizer types. The fertilization method of fruit trees generally includes ring fertilization. Fertilization in the ditch, fertilization and fertilization in the whole garden. The fertilization methods of vegetables generally have two methods: base fertilizer and topdressing. The base fertilizer is a method of applying soil fertilizer to the soil before and after planting, and it is the nutrient basis for high-quality and high-yield vegetables. The base fertilizer should be based on organic fertilizer. The application method of organic fertilizer usually depends on the degree and degree of decomposing of organic fertilizer, and the organic fertilizer with poor maturity and large amount is not suitable for concentrated ditch application. It should be removed from the surface and combined with cultivated land into the soil; The better and lesser amount of organic fertilizer should be concentrated in the ditch. If the amount is too large, it can be used for ditching and half for spreading. It not only meets the nutrient requirements of vegetables, but also achieves the purpose of fertilizing the soil. When applying a hole, it is necessary to use the decomposed organic fertilizer, and it should not be applied too much to avoid causing the burning of the seedlings. When the hole is applied, the fertilizer and the soil should be evenly mixed.
(2) Topdressing Fertilizer applied in the vegetable seedling stage or after planting is called top dressing. Generally, quick-acting fertilizers are mainly used, among which nitrogen fertilizer is the main, and potassium fertilizer is the second; topdressing should be applied according to different growth and development stages of vegetables, and the principle of less application and diligence should be adopted. The number of top dressings can be determined according to the length of the growing period of vegetables. Vegetables with short growth period can be used for 1 to 3 times in the middle of growth. Vegetables with long growing period can be used for 3 to 5 times in the period of more nutrient demand. frequency. Generally, the fat is chased once every 15 to 20 days. If the amount of topdressing is too large, not only can the vegetables not be absorbed, but also the burning of seedlings and waste, and the soil salt concentration is too high, which hinders the growth of vegetable roots.
(3) Top dressing is also called foliar spray fertilizer. This method is simple and easy. It can improve the photosynthesis and enzyme activity of leaves, thus improving root nutrition, promoting root development, enhancing absorption capacity and promoting overall plant metabolism. process. The use of small amount of fertilizer, quick effect, and not affected by the nutrient distribution center, can meet the crop requirements in time and avoid the loss or fixation of certain elements in the soil. But root dressing is not a substitute for soil fertilization. Both have their own characteristics, complement each other, and use them properly to exert the maximum effect of fertilization.
2. Several kinds of irrigation and fertilization methods commonly used in protected areas have been widely used in protected areas in recent years. The soil fertilization methods in protected areas can generally be combined with various irrigation methods such as gully irrigation, sprinkler irrigation, drip irrigation and seepage irrigation.
(1) The method of fertigation combined with gully irrigation is generally to set up various fertilization facilities at the head end of the field, such as fertilization ponds, etc. Sometimes, a small pit can be dug in the field, plastic film is placed instead, and various fertilizers are placed. After entering the pool and dissolving it, it flows into the field with water and enters the root layer of the crop. In the protected area for fertilization of alfalfa, the following issues should be noted:
1 The concentration of the fertilization solution is strictly controlled between 0.2% and 0.3%;
2 must pay attention to the fertilization period in the irrigation.
(2) Irrigation fertilization method combined with drip irrigation This method is partially irrigated. Local fertilization, water and fertilizer efficiency is higher, while the fertilization concentration can be adjusted, relatively safe, and has the effect of effectively reducing the air humidity of the protected area and preventing the spread of pests and diseases. In drip fertigation, it is generally achieved by adding a fertilizing device in the system. Commonly used fertilization (pesticide) devices include differential pressure fertilization tanks, open fertilizer tanks, venturi fertilisers, and injection pumps. The structure of various common fertilization devices is as follows:
1 Differential pressure fertilization tank: The differential pressure fertilization tank consists of a liquid storage tank, an inlet pipe, a water pipe and a pressure regulating valve, as shown in Figure 5-4.
The pressure difference type fertilization tank fertilization operation process is: after the normal operation of the watering system, the soluble fertilizer or fertilizer solution is first injected into the liquid storage tank 1, and then the can lid is closed; the valve 6 is opened to open the fertilizer supply tube 7 and then opened. Valve 4, and the inlet pipe 2 is turned on, at this time, the pressure of the liquid storage tank and the water delivery pipe are balanced. Then, the small fertilizer pressure regulating valve 5 is closed, so that the pressure difference in the water pipeline before and after the valve is generated, so that the fertilizer in the tank under the pressure, through the fertilizer pipeline into the valve, the water storage tank also causes the liquid storage tank The internal pressure is reduced. This cycle is repeated until the fertilizer in the tank is finished, and new fertilizer is added. The advantage of the differential pressure fertilization tank is that it is simple to manufacture and manufacture, and the cost is low, and no additional power equipment is needed. The disadvantage is that the concentration of the fertilizer solution varies greatly and cannot be controlled. The volume of the tank solution is limited, and the number of added fertilizers is frequent.
3 Open fertilizer tank self-pressure fertilization device: In the self-pressure irrigation system, it is very convenient to use open fertilizer tank or build a fertilizer tank. Simply place the fertilizer tank in the proper position under the self-pressing water source, connect the fertilizer water supply pipe to the water source through the control valve, connect the infusion pipe and the valve to the main pipe of the irrigation system, and open the fertilizer supply valve according to the required opening degree. Fertilize. Open fertilizer tanks are commonly used in single shed independent irrigation systems or in self-pressure irrigation systems.
3 Venturi Fertilizer Injector: The Venturi Fertilizer Injector can be used in conjunction with an open fertilizer tank to form a fertilizing device. The utility model has the advantages of simple structure, convenient use and low cost. Mainly used as a fertilizing device for small irrigation systems. The structure of the Venturi fertilizer injector is shown in Figure 5-6. The disadvantage is that if it is directly connected to the main pipe, it will cause a large pressure loss.
4 Infusion pump: In the irrigation system, a piston pump or a diaphragm pump is often used to inject fertilizer solution or pesticide into the irrigation pipeline. According to the power source of the driving water pump, it can be divided into two types: hydraulic drive and mechanical drive. Figure 5-6 shows the piston type fertilizer pump, and Figure 5-7 shows the hydraulic fertilizer pump. The advantage of using this type of device is that the fertilizing device can uniformly supply fertilizer to the irrigation water source, thereby ensuring that the concentration of the fertilizer water is stable, the fertilization quality is good, and the efficiency is high; the disadvantage is that additional power equipment and injection pump are needed, so the cost is higher. high.
In order to ensure that the irrigation system fertilization (application) device operates normally during fertilization (application) and that the irrigation water source is not contaminated, the irrigation system does not work properly due to fertilization (application), and the irrigation system applies fertilizer (application) The following points should be noted when using the device: The application device for fertilizer and pesticide should be installed between the water source and the filter, so as to ensure that the fully dissolved fertilizer or pesticide neither pollutes the water source and can be filtered after entering the subsequent irrigation. The system ensures that undissolved fertilizers and other impurities will not enter the water trap and avoid clogging of the emitter and its piping.
(b) After fertilizing or applying pesticides, be sure to leave residual pesticides or fertilizers in the irrigation system or fertilizing device. Therefore, after fertilization and application, rinse the residue left in the fertilizer tank or pesticide application device with clean water to prevent the fertilization, application device and pipeline from being corroded.
(c) A check valve should be installed between the fertilizer or pesticide application device and the water source to prevent the dissolved fertilizer or liquid from flowing into the water source and contaminating the water source. In particular, it should be noted that chemical fertilizers or pesticides cannot be directly added to water sources to prevent pollution of water sources and even the environment caused by chemical fertilizers or pesticides.
(d) Fertilizer and application device When applying different fertilizers and pesticides in different growth stages of crops, it is necessary to make the applied fertilizers both uniform and safe. Therefore, it must be completed according to certain operating procedures. If the spraying task of foliar fertilizer is finally completed by using the micro sprinkler irrigation system, the irrigation should be carried out first, and then the fertilizer or pesticide should be applied when the irrigation quota is close, and the amount and time of flushing the fertilization and application device should be reserved.
(3) Irrigation and fertilization methods combined with sprinkler irrigation, micro-sprinkler irrigation and fog irrigation can be combined with sprinkler irrigation, micro-sprinkler irrigation, and fog irrigation to carry out soil fertilization or root dressing, which is characterized by external fertilization. For convenience, the effect is very good. Its fertilization device is similar to irrigation. When spraying foliar application, pay attention to the type of fertilizer applied. Only water-soluble fertilizer and organic fertilizer leaching solution can be sprayed with foliar surface, and attention should be paid to the concentration of spraying. If the concentration is too high, it will cause burning. seedling. Foliar fertilization, in addition to a large number of commonly used elements and trace elements such as urea, potassium dihydrogen phosphate, potassium sulfate, potassium nitrate, compound fertilizer, etc., at present, many manufacturers have developed a large number of elements and trace amounts suitable for crop foliar application. Elements, or fertilizers containing a variety of amino acids, have a certain effect. A small amount of neutral detergent should be added when spraying a large amount of elemental fertilizer to increase the adhesion and improve the effect of spraying fertilizer.
Foliar application of phosphorus and potassium fertilizer should be used in the young fruit stage of cloth and melon vegetables to promote fruit expansion; legumes and leafy vegetables can be used in addition to phosphorus and potassium fertilizer in the growing season. Spraying borax during breeding to the beginning of flowering can increase seed yield.
Foliar application of fertilizer is required to be carried out on a windless sunny day. It is best to spray it after 4 pm in the daytime. In the greenhouse, the shed can be sprayed in time after the dew is dropped. The spraying frequency of foliar fertilization is generally 2 to 3 times. It can also be determined according to the condition of vegetable deficiency and the speed of nutrient running in vegetables. For example, nitrogen and potassium nutrients can run fast, and the number of spraying can be less. Spraying 1 or 2 times during the growth period or critical period; the transfer rate of phosphorus is slow, and it can be sprayed 2 to 3 times. The trace elements are extremely weak in the vegetable body and can be sprayed 3 to 4 times. The type, concentration, period and frequency of fertilizer applied to foliar application.
At present, various irrigation and fertilization methods are mutually infiltrated and supplemented, for example, soilless cultivation of vegetables using nutrient solution is an example. Because it does not use soil, fertilizer and water recycling, no pesticide pollution, it is attracting attention as a means of production of vegetables. This kind of water supply and fertilizer can not only produce celery, lettuce, duck celery, shallots and other leafy vegetables, but also can produce tomato, cucumber, strawberry and melon and other fruits and vegetables, and its cultivation range is still expanding. The appropriate concentration of urea sprayed on its foliage.
There are many ways to cultivate nutrient solution, and Figures 5-8 are schematic diagrams of one way.
(II) Fertilizer characteristics of vegetables Irrigation is not only a measure for supplying water to vegetables, but also a means of fertilizing vegetables. Although China's vegetable cultivation has rich and unique experience in using organic fertilizer combined with traditional surface irrigation methods, it has only been nearly 30 years in the application of chemical fertilizer combined with irrigation. There are still many problems to be solved. This section attempts to provide a basis for rational fertilization and irrigation through the preliminary induction of scientific research results in this area in recent years, so as to achieve high-quality, high-yield and high-efficiency production purposes.
1. The average nitrogen uptake of vegetables in vegetables requires fertilizers and fertilizers to be 0.4 times higher than wheat, 0.2 times higher in phosphorus uptake, 4.3 times higher in calcium absorption, and 0.54 times higher in magnesium absorption. At the same time, vegetable fertilizer requires the following characteristics:
(1) Different vegetable varieties require different types of vegetables. Different types of vegetables absorb different amounts of nutrients in the soil, which depends mainly on the absorption capacity, yield, growth period, growth rate and other ecological conditions of the root system. In general, vegetables with deep roots, wide branches, and root hairs have large contact points between roots and soils, and can absorb more nutrients; the nutrient elements of vegetables with shallow roots and small distribution range are small. For example, carrot roots are 3 to 4 times longer than onion roots, and the lateral growth range is doubled, and the area for nutrient absorption is 19 times larger. Therefore, the roots of carrots are much more absorbent than onions. At the same time, vegetables with high yields absorb more nutrients. In the same vegetable, when the yield level is increased, the amount of nutrients absorbed from the soil per unit area also increases, and the amount of mineral nutrients required per unit of production is relatively reduced. Therefore, the higher the yield per unit area, the greater the yield increase benefit of fertilizer.
Different types of vegetables have different growth periods and growth rates. The total amount of general fertilizer is long in the growing period; the amount of fertilizer absorbed in the general unit of time is high, and the fertilization should be guided by the strength of the fertilizer, and the total amount of the fertilizer is also referred to.
Due to phylogenetic and genetic reasons, the total amount of nutrients in the soil absorbed by different vegetables is different. According to this, vegetable crops can be divided into the following four categories:
1 large absorption, such as cabbage, Chinese cabbage, carrots, beets, potatoes, etc.;
2 medium absorption, such as tomato, eggplant, etc.;
3 absorption is small, such as spinach, celery, knotted lettuce, etc.;
4 absorption is very small, such as cucumber, water radish.
The ability of different types of vegetables to utilize mineral nutrients is also different. For example, cabbage can use nitrogen most. Beet can use phosphorus most. The demand for three elements is large. The ability of tomato to use phosphorus is the weakest, but it has no adverse reaction to a large amount of phosphorus. Therefore, understanding the fertilizer characteristics of different vegetables and fertilizing as needed can improve the fertilization effect.
Different varieties of the same vegetable require different fertilizers. The sorghum tolerance and fertility of the cultivar are determined by genetics. Early-maturing cultivars generally have a fast growth rate and a large amount of fertilizer per unit time, but the growth is short and the total amount of fertilizer is small. Therefore, it is necessary to apply quick-acting fertilizers; late-maturing varieties generally require a large amount of fertilizer and a long growth period. In addition to the need to re-apply the base fertilizer, it is necessary to apply multiple times and apply long-acting fertilizer early.
(2) Different fertilizers in the same growth period require different fertilizers. In terms of the whole development period of vegetables, the growth of seedlings is small and the nutrient elements are less. For example, the absorption of nutrients in cabbage seedlings is only 1/5 to 1/6 of that of adult plants, but the relative growth rate in seedling stage is fast, requiring full and large amounts of fertilizer components. As the plants grow, the amount of fertilizer is gradually increased. When the product organ is formed, the growth amount reaches the peak value and the fertilizer amount is also the most. Generally, the ability of the adult plant to bear the concentration of the soil solution is 2 to 2.5 times larger than that of the seedling.
The requirements for fertilizer types in different growth stages of vegetables are also different. Generally, nitrogen is needed in the whole growth period, especially leafy vegetables. When the supply of nitrogen fertilizer is sufficient, the vegetative growth is good, the chlorophyll content in stems and leaves is high, the leaves are dark and the functional period is long. Phosphorus is also needed in the whole growth stage, especially in the seedling stage of fruit and vegetable, the amount of flower bud differentiation has a good effect on increasing the quantity and quality of flower bud differentiation. (3) Different types of vegetables and vegetables require different types and types of vegetables. Different vegetables and organs have different fertilizer characteristics. Leafy vegetables generally require more nitrogen. Multiple nitrogen fertilizers are beneficial to increase yield and improve quality. Phosphorus and potassium are more abundant. The application of phosphorus and potassium fertilizers is conducive to the expansion of its product organs; the needs of the three elements of fruit and vegetables are relatively balanced, especially in the fruit formation period.
Different types of leafy vegetables require different fertilizers. Green leafy vegetables require the most nitrogen during the whole growth period, and fast-acting nitrogen should be used. Although the leaves and leaves need more nitrogen, it is mainly in the seedling stage and the initial stage of the rosette. When entering the vigorous growth period, it is necessary to increase the application of phosphate fertilizer and potassium fertilizer. When the phosphorus and potassium are insufficient, it is not easy to form a ball. Roots and stems still need a lot of nitrogen fertilizer in the seedling stage, and need a proper amount of phosphate fertilizer and a small amount of potassium fertilizer. When the roots and stems are swollen, a large amount of potassium, an appropriate amount of phosphorus and less nitrogen are needed. If there is too much nitrogen in the whole growth period and the supply of potassium is insufficient, the upper part of the plant is prone to be long, and the fleshy roots, roots, tubers, rhizomes, bulbs, etc., which are product organs, cannot be fully expanded because they do not have sufficient nutrients. If the nitrogen fertilizer is insufficient in the early stage, the growth is slow, the area of ​​the functional leaves (the rosette leaves) is small, and the development is slow, so that when the roots and stems are swollen, the nutrient supply is insufficient and the yield is low. Fruit and vegetable require more nitrogen and phosphorus in the seedling stage. The relative absorption of potassium is less. After entering the reproductive growth period, the demand for phosphorus increased sharply, while the absorption of nitrogen decreased slightly. If there is too much nitrogen in the later stage and the phosphorus is insufficient, the stems and leaves are long and affect the result. In the early stage, when the nitrogen is insufficient, the plants are small, and when the phosphorus and potassium are insufficient, the flowering period is postponed, and the yield and quality are also reduced. In addition, vegetables have different requirements on the form of soil nutrient elements. Mineral elements have their own forms, such as nitrogen with hinged nitrogen, nitrate nitrogen, urea nitrogen, phosphorus with phosphoric acid, and phosphate rock.
At the same time, the amount of boron in vegetables is much higher than that of gramineous plants, so the amount of boron required is also high.
2. The amount of fertilization of vegetables is determined to meet the requirements of nutrients for vegetable growth and development, and to achieve economic and rational fertilization and irrigation, the types and dosages of fertilizers should be determined according to external conditions such as soil nutrient requirements and soil fertility levels. Period and fertilization methods. (1) Nutritional diagnosis method of vegetable plants The nutrient content of various vegetables in different growth stages is different. It can be used to guide rational fertilization irrigation by diagnosing whether it is sufficient. The sampling time, location and standard of main vegetable plants are listed in Table 5- 11.
(2) Soil fertilization method According to the difference between the fertility element requirements of different types of vegetables and the local soil fertility elements, the amount of fertilization of vegetables is determined. The calculation formula is as follows:
Fertilizer dosage = (requires element amount - soil element content - organic fertilizer dosage × organic fertilizer content factor × organic fertilizer utilization coefficient) / (fertilizer element content × fertilizer utilization coefficient)
In the formula, the amount of elements required for various vegetables is determined, and the amount of soil elements can be obtained according to local soil fertility. The nutrient content of organic fertilizer is shown in Table 5-13; the utilization rate of different fertilizers under different external conditions is generally: organic Fertilizer (for base fertilizer) is 20% to 30%, nitrogen and potassium in fertilizer are 50% to 70%, and phosphate fertilizer is 20% to 40%.
(3) Determination of the amount of fertilizer applied to the vegetable field. In addition to considering the soil fertility status and the nutrient uptake of the vegetables, attention should also be paid to the yield of the vegetables and the quality of the fertilizer.
When fertilizing, take care to prevent high salt damage caused by excessive use. For example, cucumber is a medium salt-tolerant vegetable. When the salt content in the soil reaches 0.2% to 0.3%, its growth is severely inhibited, and the yield is reduced by 1/2. The amount of one application should generally not exceed 2/3 of the maximum limit. In particular, care should be taken when applying ammonium chloride and potassium chloride, as chlorinated salts have the most significant effect on increasing the concentration of soil solutions. When there is no data, the proportion of fertilization and the number and number of top dressings of vegetables are shown in Table 5-12 and Table 5-14.
(3) Calculation of fertilizer characteristics and fertilization amount of fruit trees
1. Fertilization characteristics of fruit trees The demand for fertilizer in fruit trees varies with the growth of tree age, the increase in the amount of results, and changes in environmental conditions. Generally, citrus fruit trees require a large amount of fertilizer, which is often twice as much as apples per year; apples, grapes, etc. are more tree species in deciduous fruit trees. At the same time, the amount of fertilizer required for the same species of fruit trees is not the same. For example, rosin and green banana apples are usually applied twice as much as other varieties to produce good results. Even for the same variety, the nutrient content and growth of the tree are different because of different nutrient and fertilizer supply conditions. Such as Bayun pear, rootstock, etc., the content of nitrogen and phosphorus in the leaves is high, and the growth of new shoots is large. Therefore, the amount of fertilization should be appropriately increased or decreased according to different rootstocks in order to make the tree healthy and productive. The fertilization of fruit trees varies with the growth stage of fruit trees. Generally, saplings and saplings need less fertilizer, which can be appropriately applied; trees with large trees and many results should be applied appropriately.
The excessive or insufficient amount of fruit trees has adverse effects on the growth and development of fruit trees. According to the report of the Liaoning Provincial Institute of Agricultural Sciences (1971), the amount of fertilizer absorbed by fruit trees increased with the increase of fertilizer application within a certain range; when the amount exceeded, the amount of fertilizer increased decreased. The absorption of 0.35 kg of nitrogen was the highest, while the difference of 0.6 kg or more with the plant was 0.25 kg, which indicated that the excessive application of fruit trees could not be absorbed.
2. Method for determining the amount of fertilizer applied
(1) Summarizing the experience of mass fertilization People in the fruit areas of China have accumulated valuable experience in fertilization in long-term production practice. Therefore, extensive investigations were carried out on the types and quantities of fertilization in local orchards, and comprehensive analysis and analysis of tree potential, yield and quality of different orchards were carried out, and the effects of fertilization were summarized to determine the amount of fertilization that could ensure the tree potential and obtain early fruit and high yield. And in the production practice combined with the results of tree growth results, and constantly adjust, so that the amount of fertilizer is more in line with the requirements of fruit trees, is an effective method, simple and practical, strong practical.
(2) Field Fertilizer Test Field fertilizer tests were conducted on different tree species and varieties by region, and the amount of fertilizer was determined based on the test results. The method is reliable and easy to use. According to the survey data, the ratio of nitrogen, phosphorus and potassium should be paid attention to when fertilizing common fruit trees, see Table 5-15.
(3) Leaf analysis The leaves of fruit trees can generally reflect the nutritional status of trees in a timely and accurate manner. Analysis of the leaves, can find the symptoms that are invisible to the naked eye, analyze the lack or excess of various nutrient elements, determine the type and quantity of fertilizers suitable for application, the method is more reliable, and can give the deficiency status of fruit trees in time. To ensure the normal growth and results of fruit trees. This method has been applied more and more widely in recent years.
For leaf analysis, the leaves are harvested directly when the leaf nutrient changes are small. For deciduous fruit trees, it is advisable to pick the leaves after germination and when the growth is stopped, and the storage status of the tree in the first year and the accumulation level of the year can be measured. Citrus fruit trees adopt leaves with leaf ages from May to July, and also reduce sampling errors. Generally, they represent 5 to 10 fruit trees, and generally do not produce spring shoots with a total of 100 to 200 tablets.
The nutrient content of leaves often varies with tree species, variety, age, rootstock and area. The leaves of citrus, apple and peach have higher nitrogen content; the same species have different varieties.
3. Calculation of fertilization amount (calculation of theoretical fertilization amount) Before calculating the fertilization amount, it is necessary to measure the amount of nutrients absorbed by the fruit preparation organs from the soil every year (Table 5-16), deducting the energy supply in the soil, and then considering the loss of fertilizer. The difference is the amount of fertilizer applied.
The following formula can be used in the calculation:
Fertilization amount = (amount of fertilizer absorbed by fruit trees - soil supply) / fertilizer utilization
In the formula, fruit nutrient fertilizers are given in Tables 5-15. The soil supply can generally be 1/3 of the absorption of nitrogen, 30% of phosphorus, and 40% of potassium. Due to the application of liquid fertilizer and irrigation, the fertilizer utilization can be significantly improved. The rate of fertilizer utilization mentioned above can be appropriately increased.
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