Cultivation method of asparagus, and liquid mulching agent used in the cultivation method

Abstract

To provide a method for cultivating asparagus in which a sprout germinating from an underground stem, which is grown to a prescribed length, is harvested, and a nursery plant of asparagus is prevented from being affected with stem blight.SOLUTION: In early spring, a first liquid mulching agent is sprayed on a farm field where an underground stem of asparagus grows, and, corresponding to a stem establishment period after asparagus is harvested in a state where the field is covered by a black covering film, and a second liquid mulching agent is sprayed on the farm field and stalks of nursery plants and they are covered by a white covering film, by which rise of a soil temperature is suppressed to promote growth of a tough underground stem, and a stem of nursery plant is prevented from being affected with stem blight due to attachment of muddy splash water containing pathogens in raining.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a cultivation method of asparagus eaten as a vegetable and a technical field of a liquid multi-agent used in the cultivation method.

Background Art

[0002] Generally, asparagus is known as a vegetable, but the asparagus is classified as a member of the genus Asparagus in the family Asparagaceae. The emergence of new shoots (germination) accompanies sowing, and the growth of the new shoots and the elongation of the stems are the same as those of many vegetables (plants). However, it is not the case that the new shoots germinated from the sown seeds are grown to the harvest height (for example, 25 cm) and then harvested and eaten. After sowing, for example, for about two years, the germination and stem standing of the new shoots are repeated to promote the growth of the underground stems (underground strains, root stocks). Then, after the spring of the third year, the young stems that have grown to the harvest height from the new shoots germinated from the underground stems that have stored nutrients and grown are harvested, and the harvested stem parts are put on the market as asparagus. Such asparagus can continue to harvest stems for many years (10 to 15 years) after the third year after normal sowing. For this purpose, in the year of sowing, the new shoots germinated from the sown seeds are grown large without being harvested to cultivate the stock, and overwinter as underground stems in which nutrients generated by photosynthesis by the lush stems and leaves of the stemmed plants are accumulated. In the following second year, it is allowed to grow upright without harvesting again, and further accumulate in the rhizome, growing and overwintering as the rhizome that has accumulated nutrients. And from the third year onwards, for example, in the Kanto region, as shown in Figure 4, the spring shoot harvesting period, during which new shoots that have started to germinate in early spring from February to March and reached a predetermined height are cut and harvested, continues from approximately April to May. After that, from May to June is the stem-growing period. Selecting strong new shoots, it is allowed to grow without harvesting to form a mother stem with lush foliage. During this stem-growing period, the nutrients produced by the photosynthesis of the leaves of the stems that have grown upright are accumulated in the rhizome. After the stem-growing period, from October to November, new shoots continue to germinate from the rhizome that continues to accumulate due to stem growth, which becomes the summer shoot harvesting period, and the harvesting of asparagus continues. As autumn deepens, the underground part withers, while the rhizome overwinters in a state where nutrients are accumulated. By repeating such a cycle, asparagus is a vegetable that can be harvested repeatedly over many years as described above. In the cultivation of such asparagus, stem blight is known as one of the major diseases. The pathogen of this stem blight (Diaporthe asparagi (Phomopsis asparagi)) is a type of filamentous fungus. When the pathogen of stem blight attaches to and infects the stem of the growing stem and causes disease (primary infection), the infected part turns light brown. As the infection progresses, black (dark brown) spotted things appear on the infected part. These spotted things are called pycnidia. And in these pycnidia, countless conidia that become pathogens are produced. When the growth of the conidia is complete and the pycnidia break, the conidia scatter into the air. And it is said that when a part of these scattered conidia attaches to other stems and causes stem blight, the stem blight spreads (secondary infection). On the other hand, a part of the scattered conidia falls into the field and overwinters in the soil. These overwintered conidia become the pathogens of stem blight in the following year, and due to these factors, the spread of stem blight is repeated every year, causing great damage to the healthy cultivation of asparagus. Regarding such asparagus stem blight, a variety of control methods and control agents (disinfectants) have been developed and put into practical use to date. Among those using control agents, for example, it is preferable to control using benomyl hydrate and TPN (chlorothalonil) hydrate, and it has been reported that effective control can be achieved especially by combining control against primary infection and secondary infection (see, for example, Non-Patent Document 1). However, since asparagus is cultivated repeatedly over the years as described above, when the above control method using a control agent is carried out, the pathogenic bacteria acquire drug resistance due to repeated use of the drug over the years, not only does the control effect gradually become diluted, but there is also a risk that such control agents will remain in the environment for many years and have an adverse impact on the ecosystem, which has also become a social problem. Furthermore, although a direction of controlling by installing a house for cultivation and burning with a burner after cutting the cured plants in autumn has also been proposed, at present, there are difficulties in dealing with it, such as a large financial burden being required for the installation and maintenance of the facilities for house cultivation and it being difficult to maintain the control effect inside the house.

[0003] On the one hand, asparagus is a plant with the characteristics that the suitable growth temperature is from 10°C to 30°C and it is somewhat resistant to dryness. When cultivating such vegetables, in order to promote early germination in early spring, a black mulch sheet (film mulch) may be laid on the field surface (ridge surface) to raise the ground temperature. When this is applied to the cultivation of asparagus, as described above, since asparagus sprouts new shoots from the underground stem, it is impossible to specify in advance where the budding position of the new shoots will be. Therefore, when the mulch sheet is laid, it is virtually impossible to specify in advance the position of the budding new shoots and perform the perforation work. So, it is necessary to remove (peel off) the mulch sheet taking into account the timing of the germination of the new shoots. However, if the timing of this removal is misjudged and is too early, the germination of the new shoots will be delayed due to the decrease in ground temperature. Also, the removed mulch sheet becomes waste plastic and must be treated as industrial waste. There are problems such as poor workability and the expected adverse environmental impact associated with treating the mulch sheet as industrial waste. In view of such a situation, a liquid mulch agent has been developed and put into practical use (see, for example, Patent Document 1). This liquid mulch agent is a biodegradable black liquid. When it is sprayed on the field, it forms a black coating film and is laid on the entire field surface. Therefore, while a high mulch effect can be expected, it has the advantage that the coating film can be easily broken through by the growth force of the budding new shoots and does not hinder the germination and growth of asparagus. For this reason, the coating film of the liquid mulch agent does not need to be removed in response to the germination of new shoots like a mulch sheet and can remain in the coated state. Therefore, even in the period after the initial germination when the temperature in early spring has not risen sufficiently, it contributes to the increase in ground temperature, promoting subsequent germination and the growth of the standing stems. Moreover, the coating film of the liquid mulch agent has the advantage that it biodegrades over time and disappears, for example, by becoming nutrients, so no phytotoxicity occurs. By the way, the pathogen of asparagus stem blight thrives in the temperature range of 20°C to 30°C, and the temperature around 25°C is particularly said to be the optimal temperature for its growth. As if to prove this, it has been confirmed that the incidence of stem blight is low during the spring shoot harvesting period when the temperature has not yet risen in early spring. However, it has been confirmed that after May when the temperature rises and the standing stem period begins, the number of affected plants by stem blight increases rapidly, and in particular, there is a tendency for the number of diseased plants to increase after rainfall.

Prior Art Documents

Non-Patent Documents

[0004]

Non-Patent Document 1

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Incidentally, when we continued to attempt cultivating asparagus in the field with the coating film of the liquid multi-agent described above, in the field where stem blight occurred in the previous year, at an early stage when the temperature was less than 25°C, for the standing stems, the occurrence of stem blight was only slightly confirmed, and asparagus could be harvested without problems. However, afterwards, when the temperature approached 25°C, it was confirmed that the incidence of stem blight in the standing stems rapidly increased. This is because the pathogens of stem blight activated (activated) as the temperature approached 25°C scattered in the air (there was also scattering of pathogens from other fields where stem blight occurred) and adhered to the foliage of the standing stems, causing the disease. And as described above, as a factor for the confirmed increase in the incidence after rainfall, it is presumed that the pathogens in the soil mixed in the splashing water during rainfall such as the plum rain and evening showers repeatedly adhered to the stems of the standing stems, causing the foliage of the standing stems to be affected by stem blight and spread to the leaves. Therefore, it is necessary to address this, and for this purpose, it is first required to prevent the rise of the ground temperature and maintain the growth of the underground stems, and at the same time, take measures to prevent the adhesion of splashing water during rainfall mixed with pathogens in the soil. Furthermore, it is required to prevent the pathogens scattered in the air and mixed in the splashing water during rainfall from adhering to the cultivated plants, and to prevent the scattering of conidia when the generated perithecia are destroyed. The problems to be solved by the present invention are these issues.

Means for Solving the Problems

[0007] The present invention was created for the purpose of solving these problems in view of the above circumstances. The invention of claim 1 is a method for cultivating asparagus in which young shoots germinated from asparagus rhizomes in a field grow and the young stems that have reached the harvesting height are cut and harvested. Before the young shoots germinate from the rhizomes in early spring, a first liquid fertilizer containing a black pigment as one of the main components is sprayed on the field, and asparagus is cultivated with the field covered with a black coating film. Then, corresponding to the stem elongation period when the temperature rises, a second liquid fertilizer containing a white pigment as one of the main components is sprayed on the field, and asparagus is continuously cultivated with the field covered with a white coating film. This is a method for cultivating asparagus characterized by the above steps. The invention of claim 2 is the method for cultivating asparagus according to claim 1, characterized in that the spraying of the second liquid fertilizer is carried out when the temperature is from 18°C to 25°C, preferably 22°C. The invention of claim 3 is the method for cultivating asparagus according to claim 1, characterized in that the spraying of the second liquid fertilizer includes the foliage of the growing stems, and the surface of the foliage is covered with a coating film of the second liquid fertilizer. The invention of claim 4 is the method for cultivating asparagus according to claim 3, characterized in that the height of the coating on the surface of the foliage by the second liquid fertilizer is 5 cm or more from the field surface. The invention of claim 5 is the method for cultivating asparagus according to claim 3, characterized in that the spraying of the second liquid fertilizer on the field may be repeated, and the repeated spraying of the second liquid fertilizer is carried out when more than 1 / 4 of the coating film of the previously sprayed second liquid fertilizer has disappeared. The invention of claim 6 is the method for cultivating asparagus according to claim 3, characterized in that the coating of the second liquid fertilizer on the foliage may also be repeated other than when the second liquid fertilizer is repeatedly sprayed on the field. The repeated coating of the second liquid fertilizer on the foliage other than the repeated spraying on the field is carried out by spraying or applying the second liquid fertilizer on the foliage. The invention according to claim 7 is a liquid multi-agent, wherein the first liquid multi-agent is a black suspension emulsion aqueous solution mainly composed of a biodegradable polymer emulsion and a dispersant in addition to a black pigment, and the second liquid multi-agent is a white suspension emulsion aqueous solution mainly composed of a biodegradable polymer emulsion and a dispersant in addition to a white pigment, and is a liquid multi-agent used in the asparagus cultivation method according to claim 1. The invention according to claim 8 is a liquid multi-agent used in the asparagus cultivation method according to claim 7, characterized in that at least one kind of agent selected from herbicides or fungicides is mixed in the first liquid multi-agent and / or the second liquid multi-agent.

Advantages of the Invention

[0008] By adopting the invention according to claim 1, when cultivating asparagus by cutting and harvesting young stems whose new shoots germinated from the rhizome have reached the harvest height, in early spring before the new shoots germinate from the rhizome, the first liquid multi-agent is sprayed to cover the field surface with a black coating film, so as to promote the early emergence of new shoots due to the increase in the soil temperature of the field and improve the spring shoot harvest. Subsequently, in response to the stem elongation period when the temperature rises, by spraying the second liquid multi-agent to cover the field surface with a white coating film, the increase in the soil temperature during the summer shoot harvest period is suppressed, the healthy germination of summer shoots is promoted, and high yields can be achieved. However, since the field surface is covered with the first and second liquid multi-agents during the spring and summer harvest periods, the pathogens of stem blight existing in the soil (overwintered) are prevented (reduced) from being mixed into the splashing water during rainfall, and the incidence of stem blight in the stemmed plants is reduced, enabling stable cultivation of asparagus. By adopting the invention according to claim 2, the spraying of the second liquid multi-agent is carried out when the temperature is between 18°C and 25°C, preferably 22°C. As a result, the increase in the soil temperature can be suppressed at a stage before the temperature reaches 25°C when the pathogens of stem blight become active, and the prevention of contracting stem blight can be achieved. By setting the invention as claimed in claim 3, by spraying the second liquid multi-agent up to the foliage of the standing stems, the surface of the foliage can be covered with the coating film of the second liquid multi-agent. As a result, even if the splashing water mixed with the pathogen of stem blight adheres to the foliage of the nursery plants, since the stem part is covered with the coating film of the second liquid multi-agent, the pathogen is prevented from adhering to the foliage, and thus the incidence of stem blight can be suppressed. By setting the invention as claimed in claim 4, since the coating height of the foliage surface by the second liquid multi-agent is 5 cm or more from the field surface where splashing water easily adheres, the infection through the splashing water can be effectively prevented. By setting the invention as claimed in claim 5, during the long summer bud harvesting period, the spraying of the second liquid multi-agent to the field may be repeated. In that case, the repeated spraying of the second liquid multi-agent is carried out when more than 1 / 4 of the coating film of the second liquid multi-agent sprayed last time has disappeared. As a result, the covering of the field surface in a white state by the second liquid multi-agent continues, which can greatly contribute not only to suppressing the rise in ground temperature but also to preventing the infection of stem blight. By setting the invention as claimed in claim 6, the coating of the second liquid multi-agent on the foliage may be repeated not only during the repeated spraying of the second liquid multi-agent to the field. In that case, the repeated coating of the second liquid multi-agent on the foliage other than the repeated spraying to the field is carried out by spraying or coating on the foliage. As a result, the coating of the second liquid multi-agent on the foliage can be efficiently achieved. By setting the invention as claimed in claim 7, since the first liquid multi-agent is a black suspension emulsion aqueous solution mainly composed of a biodegradable polymer emulsion and a dispersant in addition to a black pigment, and the second liquid multi-agent is a white suspension emulsion aqueous solution mainly composed of a biodegradable polymer emulsion and a dispersant in addition to a white pigment, biodegradable first and second liquid multi-agents can be easily prepared. By adopting the invention of claim 8, at least one type of agent selected from herbicides or fungicides is mixed in the first liquid multi-agent and / or the second liquid multi-agent. As a result, in addition to coating the field surface, herbicides or fungicides can also be sprayed, which improves workability.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0010] As described above, asparagus is a perennial plant with an underground stem. When paying attention to stem blight, if it is cultivated in a healthy field where the stem blight has not occurred, there is an advantage that it can be harvested over a long period of 3 years or more after sowing, from 10 to 15 years. As factors for the occurrence of stem blight in such a healthy field, pathogens that propagate in other fields where stem blight has occurred (propagation sites of stem blight) may be blown in by the wind, or flowing water accompanying heavy rain such as typhoons may flow from the propagation site to the healthy field. When the pathogens thus carried adhere to the asparagus seedlings, they infect and develop at the weak parts of the seedlings' resistance, and the parts showing a light brown disease state gradually spread as the infection spreads. And black spotted pycnidia are formed on the diseased parts, and when the pycnidia are destroyed, the conidia that become pathogens scatter into the air. And in this way, a healthy field becomes infected with stem blight (primary infection), and further, due to this, stem blight spreads (secondary infection) in the field, and this spread is repeated over the years. As countermeasures against such stem blight, although the pathogen of stem blight is said to have a growth temperature in the range of approximately 20°C to 30°C, in order to suppress the occurrence and spread of stem blight, ·Eliminating pathogens in the field before the germination of new shoots ·Suppressing the adhesion of pathogens by splashing water with mud during rainfall on the standing stems and leaves ·Suppressing the growth of the infected pathogens ·Suppressing the adhesion of pathogens carried from other infected fields are important issues, and the specific issue of the present invention is how to achieve the elimination or reduction of chemical spraying by dealing with any one of these issues.

[0011] The present invention provides a cultivation method using a liquid multi-agent to deal with stem blight of asparagus, and a liquid multi-agent used in the cultivation method. The liquid multi-agent used herein includes a first liquid multi-agent and a second liquid multi-agent. Among the main components used in any of the liquid multi-agents, the main components other than the pigment are biodegradable, harmless (non-toxic) to animals and plants, and will not accumulate in the field over time due to biodegradation, and it is preferable to use those that can be absorbed as plant nutrients. Since the first liquid multi-agent contains a black pigment as the main component, when it is sprayed on the field, it forms a gel-like coating film that turns black on the field surface and is laid in a sheet shape. On the other hand, the second liquid multi-agent contains a white pigment as the main component, and when it is sprayed on the field, it forms a gel-like coating film that turns white on the field surface and is laid in a sheet shape. The coating films formed by spraying these first and second liquid multi-agents on the ridge surface at different times will be easily broken through by the germination force (growth force) of the new shoots germinated from the asparagus rhizomes in the field, and the presence of the coating film will not affect the germination and growth of the new shoots.

[0012] The first liquid multi-agent is sprayed on the ridge surface in early spring before new shoots germinate from the rhizomes. In this way, similar to the case of being covered with an existing mulch film, a coating film of the first liquid multi-agent is formed on one side so that there is no soil exposure on the ridge surface. In the field where the coating film of the first liquid multi-agent is formed in this way, since the coating film of the first liquid multi-agent is black, in early spring when the ground temperature is not yet sufficiently high, it can absorb sunlight well and exhibits an excellent ground temperature rising effect. As a result, the rhizomes are activated at an early stage, promoting the germination of strong new shoots at an early stage and also exhibiting a function of preventing the growth of weeds. Incidentally, for the spraying of the first liquid multi-agent on the field, usually one application is sufficient. However, in cold regions such as Hokkaido, or in the case of a cold damage state where the temperature does not rise significantly even in early summer, it is also possible to spray again after observing the disappearance situation of the coating film.

[0013] On the other hand, the second liquid multi-agent can be sprayed on the ridge surface even when it remains on the ridge surface before the black coating film generated by spraying the first liquid multi-agent is completely decomposed and disappears. As for the timing of spraying the second liquid multi-agent, it is preferably corresponding to the standing stem stage when the spring harvest is over, or around that time, and when approaching the early summer when the temperature rises. However, when using the temperature as a reference, it is preferably carried out with reference to the stage approaching 22°C before reaching 25°C, which is said to be the temperature at which stem blight grows most vigorously. This sprayed second liquid multi-agent forms a white coating film in a sheet shape on one side by spraying the field surface including the residue part of the first liquid multi-agent so as to have no exposure. In the field where the coating film of the second liquid multi-agent is formed in this way, since the coating film of the second liquid multi-agent is white, it reflects strong sunlight and suppresses the rise of the ground temperature, thereby suppressing the situation where the ground temperature becomes too high for the growth of the underground stem and inhibiting the proper growth of the underground stem, promoting the activation of the underground stem, exerting the effect of promoting the emergence of strong new shoots, and also exerting the function of preventing the overgrowth of weeds. As for the second liquid multi-agent, it is preferably repeatedly sprayed as needed until the cultivated plants wither or are removed in autumn. In that case, it is preferable to spray the second liquid multi-agent when at least 1 / 4 or more of the coating film generated by the previous spraying has disappeared. Needless to say, the second liquid multi-agent may be sprayed at a disappearance stage of 1 / 4 or less if necessary. In this case, the spraying may be carried out on the periphery including the disappeared part in order to repair the part where the coating film has disappeared.

[0014] When the present invention is implemented in this way, the first and second liquid multi-agents are sprayed on the asparagus growing field to form respective coating films. Regarding the second liquid multi-agent, it is also related to the stem standing period. Also, since stem blight mainly occurs on the stems and leaves of the standing plants, it is preferable that the coating film of the second liquid multi-agent is formed not only on the field surface but also on the stems and leaves. By forming a coating film on the stems and leaves of the standing plants, there is an effect of preventing the adhesion of pathogenic bacteria on the stems and leaves due to splashing water during rainfall. Therefore, when forming the coating film of the second liquid multi-agent on the stems and leaves, it is preferably at least 10 cm or more above the field surface. When forming the coating film of the second liquid multi-agent on the stems and leaves of the standing plants in this way, it is also suitable from the viewpoint of workability to spray the second liquid multi-agent on the stems and leaves in addition to spraying it on the field surface, but it may also be sprayed targeting the stems and leaves of the standing plants. Furthermore, it may be applied to the stems and leaves of the standing plants using coating means such as a pen or a brush. And when forming the coating film of the second liquid multi-agent on the stems and leaves of the standing plants in this way, the adhesion of the pathogenic bacteria of stem blight to the stems and leaves can be prevented by the coating film.

[0015] Also, when the occurrence of stem blight is recognized in the stems and leaves of the standing plants, it is preferable to form a coating film using the second liquid multi-agent on the peripheral part including the diseased part. When the already diseased stems and leaves are covered with the coating film in this way, the growth of pathogenic bacteria and the generation of pycnidia can be suppressed. Also, even if the generated pycnidia are destroyed, the conidia cannot break through the coating film and come out, so it can contribute to preventing the scattering of pathogenic bacteria and an effect of preventing secondary infection can be expected.

[0016] The composition of the first and second liquid multi-agents used in the present invention has a black or white pigment as one of the main components, and is provided with a dispersant having an interfacial activity function to prevent precipitation of the pigment in the liquid multi-agent and containing a polymer emulsion having a function of forming a coating film as the main component.

[0017] Examples of the black pigment used in the first liquid multi-agent include carbon black, black iron, and charcoal powder. All of these are black pigments that do not affect the ecosystem and at least one selected from these pigments is used. On the other hand, examples of the white pigment used in the second liquid multi-agent include titanium oxide, zinc oxide, and lithopone. Titanium oxide can be said to be preferable as it passes the environmental substance standard test for biodegradable plastics.

[0018] Also, as the dispersant for these pigments, it is selected from materials that are biodegradable and do not affect the ecosystem even after biodegradation. Examples of such materials include humate and polycarboxylate salts as suitable ones. Humate exhibits black or black-brown color and is suitable as a dispersant for the first liquid multi-agent because it is biodegradable. Humic acid is a high molecular weight organic acid obtained by alkali extraction of young coals, weathered coals, leonardites, peat moss, or peat, or a high molecular weight organic acid obtained by oxidative decomposition of young coals, peat moss, or peat with nitric acid. Humate is an alkali metal salt or ammonium salt of a high molecular weight organic acid. And the humate functions as a dispersant to prevent the black pigment from precipitating in the aqueous polymer emulsion solution. In this case, particularly the potassium salt and ammonium salt of humic acid are classified as humic acid fertilizers in the Fertilizer Control Law, so it can be said that they are suitable dispersants to be contained as active ingredients of the first liquid multi-agent.

[0019] On the other hand, a dispersant that is the main component of the second liquid multi-agent and exhibits black color like the above-mentioned humate is not preferable because it hinders the formation of a white coating film. Therefore, it is preferable to use an anionic surfactant that is colorless or nearly colorless and does not hinder the formation of a white coating film as the dispersant. And as such a surfactant, fVarious surfactants such as the rubonic acid type, carboxylic acid type, acrylic acid type, sulfate ester type, polyphosphate ester type, etc. can be exemplified, and at least one selected from these can be adopted.

[0020] Furthermore, as one of the main components of the first and second liquid multi-agents, there is a biodegradable polymer emulsion. By spraying this polymer emulsion on the ridge surface, it has the function of forming a multi-film as a coating film on the ridge surface. It will be in a state of adhering to the sprayed ridge surface to form a uniform coating film on the ridge surface. And the formed coating film will become a water-permeable and water-resistant and breathable film with appropriate water permeability by the evaporation of the contained moisture or impregnation into the soil, etc., and will exert the function of preventing the drying of the field. Examples of such polymer emulsions include polyacrylate emulsion, polyacrylamide emulsion, polyvinyl acetate emulsion, and polycarboxylic acid emulsion, and at least one selected from these polymer emulsions can be adopted.

[0021] In this way, the first and second liquid multi-agents used to implement the present invention each contain a black or white pigment, a dispersant, and a polymer emulsion as the main components. Furthermore, polyvinyl alcohol can be added as a thickening solvent and extender pigment as a pigment extender to this. In this case, kaolin is exemplified as the extender pigment of the first liquid multi-agent, and calcium carbonate is exemplified as the extender pigment of the second liquid multi-agent.

[0022] The present invention is a method for cultivating asparagus in a field where asparagus grows by spraying a black liquid multi-agent and a white liquid multi-agent, which are mainly composed of a biodegradable polymer resin material and a black or white paint, at different times, and cultivating asparagus in a state where a coating film of these liquid multi-agents is formed. In this case, as for the field, in order to remove the pathogenic bacteria remaining in the field cultivated last year, at an early time in spring when there is no germination of new shoots, if there are remaining standing stems, the removal treatment and the sterilization treatment such as burning the field surface with a burner are carried out, and at the same time, the treatments necessary for asparagus cultivation such as spraying herbicides, fungicides, fertilizers, etc. usually used in asparagus cultivation are carried out on the field as necessary.

[0023] And when these treatments have adapted to the field, first, the black first liquid multi-agent is sprayed along the ridges. Spraying of this first liquid multi-agent is preferably carried out using a power sprayer from the viewpoint of workability. For this reason, the first liquid multi-agent is adjusted to a viscosity suitable for spraying with a power sprayer by adding water or the like. The first liquid multi-agent sprayed in this way becomes a natural drying state by evaporation of moisture and penetration into the field, and becomes a soft black coating film on the field surface. And in the field where the coating film of the black first liquid multi-agent is formed in this way, while preventing the runoff (loss) of herbicides, fungicides, and fertilizers due to rainfall, maintaining high water retention, promoting the rise of the ground temperature by the irradiation of sunlight during the day in spring, and preventing the drop of the ground temperature at night, it becomes possible to ensure a ground temperature of 15 °C or higher, which is favorable for the growth of asparagus, even at an early time in spring. This promotes the early germination of asparagus and enables early shipping, leading to an increase in revenue. Moreover, the increase in the ground temperature from an early time in spring promotes the growth of the underground stems, enabling them to be strong and robust. The new shoots germinated from here and the standing stems can generally be made highly resistant (strong) to pathogenic bacteria, resulting in an increase in the revenue effect.

[0024] After spraying the black first liquid multi-agent in this way, the white second liquid multi-agent will be sprayed. The timing of spraying the second liquid multi-agent is carried out at the stage where at least 1 / 4 or more of the coating film formed by spraying the first liquid multi-agent has disappeared. This disappearance of 1 / 4 or more is not constant due to weather conditions such as rainfall, but is at the stage where approximately 1.5 to 3 months have passed after spraying the first liquid multi-agent, and usually it is at or around the stem-standing period. On the other hand, there is a report that the temperature suitable for the growth (propagation) of the pathogen of stem blight is approximately 25°C. Therefore, it can also be selected as the timing of spraying the second liquid multi-agent to carry out it at the stage when the air temperature rises to 22°C. The time when the air temperature reaches 22°C often overlaps with the stem-standing period, and the stem-standing period can also be used as a reference. And the timing of spraying the second liquid multi-agent is affected by the change situation of meteorological conditions. In the case of seasons with a rapid rise in air temperature, it is recommended to carry out it at the stage close to the above-mentioned 22°C before the coating film of the first liquid multi-agent disappears by more than 1 / 4 even before the stem-standing period. Conversely, in the case of seasons with a slow rise in air temperature, it is recommended to take as a reference that it is after the stem-standing and the coating film of the first liquid multi-agent has disappeared by more than 1 / 4. In this case, the remaining coating film of the first liquid multi-agent may or may not be removed, but generally it is not removed from the perspective of workability. Regarding the spraying of the second liquid multi-agent as well, similar to the case of spraying the first liquid multi-agent, it is preferable to use a power sprayer. Therefore, it is also preferable to adjust the viscosity of the second liquid multi-agent by adding water or the like.

[0025] In this way, the field surface where the second liquid multi-agent is sprayed will be covered with a white coating film with uniform viscoelasticity. And the field whose surface is covered with a white coating film in this way will reflect sunlight, suppress abnormal rise of ground temperature, and can achieve the effect of maintaining the cultivation environment of asparagus, which is vulnerable to high temperatures of 30°C or more, in an appropriate state as described above. And in this case, it is preferable to spray the second liquid multi-agent not only on the field surface but also on the stems and leaves of the standing plants. When the second liquid multi-agent is sprayed even on the stems and leaves of the standing plants like this, the stems and leaves of the covered part will be covered with the coating film of the second liquid multi-agent. As a result, the attachment of the pathogens of stem blight to the stems and leaves of the covered part can be avoided, and the prevention of stem blight infection can be achieved. On the other hand, when the stems and leaves of the infected part are covered with the coating film afterwards, the contact with the outside air is blocked, so the formation of pycnidia in the infected part can be suppressed. Even if the generated pycnidia are destroyed, the destroyed pycnidia are covered with the coating film, so the scattering of the pathogens can be prevented, and it can contribute to preventing the spread of stem blight caused by secondary infection.

[0026] When covering the standing plants like this with the coating film of the second liquid multi-agent, it is preferable to make the height at least 10 cm or more from the field surface. By doing so, it is possible to effectively prevent the pathogens mixed in the splashing water from the field surface from adhering to the parent plants, especially during rainfall. And since the coating agent covering the parent plants adheres to the vertical part, it tends to disappear earlier than the one covering the field surface. In this case, the second liquid multi-agent may be sprayed again, or it may be applied using coating materials such as pens and brushes. And when spraying or applying to such parent plants, if an infected part of the disease is found during daily inspection, the second liquid multi-agent may be sprayed or applied to the discovered parent plants to form a coating film. Incidentally, when harvesting the one with the coating film of the second liquid multi-agent applied to the new shoots, the part growing above the covered part may be cut and harvested.

[0027] The coating film of the second liquid mulch that covers the field has a different durability period depending on the thickness of the coating film, but is approximately the same as the durability period of the first liquid mulch. For this reason, when the coating film of the second liquid mulch has disappeared to a certain extent, it is necessary to spray the second liquid mulch again to form a white coating film on the field surface. As the timing of this re-spraying of the second liquid mulch, it is preferably at the stage when approximately 1 / 4 of the coating film of the second liquid mulch sprayed last time has disappeared, and preferably around the time before midsummer. This is because by providing a white coating film of the second liquid mulch on the field surface again before the stage of midsummer, it is possible to prevent the rise of the ground temperature and reduce the decline of the rhizome due to high temperature during the midsummer period. And if necessary, depending on the disappearance state of the coating film of the second liquid mulch, it is of course possible to form a white coating film by re-spraying.

[0028] And when cultivating asparagus under the above conditions, it can be said that it is important to take the above-mentioned measures to deal with stem blight. Incidentally, this is the case of open-field cultivation in the plains of the Kanto region. Needless to say, in cold regions such as the Tohoku and Hokkaido regions, or the mountainous parts of Honshu, or conversely in warm regions such as the Tokai region, Shikoku, and Kyushu region, appropriate changes suitable for each region are necessary. ·Around January: Clean up the remaining stems and the field from the previous year, and burn the ground surface with a gas burner for sterilization. ·Around February to March: Spray a herbicide and a fungicide on the field, and then spray the black first liquid mulch to cover the entire ridge surface with the coating film of the first liquid mulch. This prevents the sprayed herbicide and disinfectant from being washed away (runoff) by rain, promotes the activation of strong rhizomes while raising the ground temperature and maintaining the water retention of the field, and in the early cases, asparagus germination is observed. · Around March to May: This is a season when stem blight is less likely to propagate before the average temperature reaches 22°C. By covering with the coating film of the first liquid fertilizer, the ground temperature rises and the water retention of the field is ensured. Asparagus grows vigorously from the strong underground stems in an environment suitable for growth, and vigorous and healthy new shoots resistant to pathogens such as stem blight germinate abundantly. Those that have grown to a predetermined length in the early stage can be cut for initial harvesting. · Around May to June: After the initial harvesting is completed, strong new shoots are considered and the stems are allowed to grow. At this time, the temperature becomes 22°C or higher, creating an environment where the pathogens of stem blight proliferate vigorously. Before that, the white second liquid fertilizer is sprayed on the field to form a coating film of the second liquid fertilizer on the ridge surface. And when the white coating film is formed, it reflects sunlight, suppressing the rise of soil temperature, protecting the temperature of the underground stems vulnerable to high temperatures, preventing the weakening of the underground stems, and promoting the growth of strong standing stems. The spraying of the second liquid fertilizer is not only on the ridge surface but also on the stems and leaves of the mother plants to cover the surface of the stems and leaves with a white coating film. · Around June to August: In the field with high temperature, the growth of the mother plants comes to an end. The underground stems grow by obtaining the nutrients generated by the photosynthesis of the grown mother plants, and new shoots are promoted to germinate and can be harvested. However, since the soil is covered with the coating film of the white second liquid fertilizer, splashing water caused by rainfall such as the plum rain and evening showers is suppressed, preventing the pathogens of stem blight from adhering to the mother plants. For those that already have the pathogens of stem blight adhering and have developed the disease, the generation of conidia can be suppressed. Also, even if the conidia grow and break, the scattering of the pathogens can be prevented, enabling the high prevention function of secondary infection to be exerted, and the continuous harvesting of asparagus can be stably achieved. · From around August to October: While the continuous harvesting of asparagus can be carried out stably, the white coating gradually disappears. When approximately 1 / 4 of the field surface is exposed, spray the second liquid fertilizer on the field surface again, including the cultivated plants, to reform the white coating, suppress the propagation of stem blight, promote the photosynthesis of the cultivated plants until they grow until late autumn and wither, and ultimately cultivate strong rhizomes in preparation for the next year.

[0029] Next, the formulation examples of the components of the first and second liquid fertilizers will be described. First, regarding the formulation example of the first liquid fertilizer, when carbon black, humic acid, vinyl acetate emulsion, Poval, and kaolin as an extender pigment are adopted as the components of the first liquid fertilizer, the first liquid fertilizer is formulated as follows (unit: parts by weight). Carbon black: 100 - 1000 3 - 20 wt% aqueous solution of humate: 1000 - 2000 Vinyl acetate emulsion: 3000 - 6000 10 - 20 wt% aqueous solution of polyvinyl alcohol: 1000 - 2000 Kaolin: 500 - 2000 And as a method for manufacturing the first liquid fertilizer using the components formulated in this way, carbon black is mixed into the aqueous solution of humate and dispersed with a mixer to obtain a slurry-like mixture. An aqueous solution of polyvinyl alcohol is added to this mixture and mixed well, and then vinyl acetate emulsion is further added and mixed. Further add kaolin to this and mix, and adjust the viscosity with purified water to obtain a black first liquid fertilizer.

[0030] On the other hand, regarding the formulation example of the second liquid fertilizer, when titanium oxide, an anionic surfactant, vinyl acetate emulsion, polyvinyl alcohol, and calcium carbonate as an extender pigment are adopted as the components of the second liquid fertilizer, the second liquid fertilizer is formulated as follows (unit: parts by weight). Titanium oxide: 100 - 1000 Aqueous solution of an anionic surfactant: 3 to 20% by weight, 400 - 1000 Vinyl acetate emulsion: 3000 - 6000 Aqueous solution of polyvinyl alcohol: 10 to 20% by weight, 1000 - 6000 Calcium carbonate: 500 - 2000 And, as a specific production method of the second liquid multi-agent, titanium oxide (R - 630 manufactured by Ishihara Sangyo Co., Ltd.) is mixed into an aqueous solution of an anionic surfactant (Adekacol CS1361E manufactured by ADEKA Corporation) and dispersed with a mixer to obtain a slurry-like mixture. To this mixture, the above-mentioned aqueous solution of polyvinyl alcohol is added and mixed well, and further the above-mentioned vinyl acetate emulsion is added and mixed. To this, calcium carbonate (Newlite F manufactured by Nitto Funka Kogyo Co., Ltd.) is further added and mixed, and the viscosity is adjusted with purified water to obtain a white second liquid multi-agent. Experimental examples

[0031] Next, the experimental examples of the present invention will be described together with comparative examples. <Preparation of the first liquid multi-agent> The first liquid multi-agent was prepared with the following formulation (parts by weight). Carbon black: 500 Aqueous solution of humate: 10% by weight, 2000 Vinyl acetate emulsion: 5000 Aqueous solution of polyvinyl alcohol: 10 to 20% by weight, 1500 Kaolin: 1000 As a method for specifically manufacturing the first liquid multi-agent using the prescribed components, carbon black (Mitsubishi Carbon MA100 manufactured by Mitsubishi Chemical Corporation) is mixed into an aqueous solution of humate (CH-03 manufactured by Teranite Co., Ltd.) while being stirred by a mixer (stirrer) and dispersed by the mixer to obtain a slurry-like mixture. An aqueous solution of polyvinyl alcohol (28-98 manufactured by Kuraray Co., Ltd.) is added to this mixture and mixed well. Further, vinyl acetate emulsion (Vinar EM232 manufactured by Kanae Chemical Industry Co., Ltd.) is added and mixed. Further, kaolin (Hardmill manufactured by Takehara Chemical Industry Co., Ltd.) is added to this and mixed, and the viscosity is adjusted with purified water to obtain a black first liquid multi-agent.

[0032] <Preparation of the second liquid multi-agent> The second liquid multi-agent was prepared with the following formulation (parts by weight). Titanium oxide: 500 10 wt% aqueous solution of anionic surfactant: 800 Vinyl acetate emulsion: 4000 10 wt% aqueous solution of polyvinyl alcohol: 3000 Calcium carbonate: 1000 As a method for specifically manufacturing the second liquid multi-agent using the prescribed components, titanium oxide (R-630 manufactured by Ishihara Sangyo Co., Ltd.) is mixed into an aqueous solution of an anionic surfactant (Adekacol CS1361E manufactured by Adeka Corporation) while being stirred by a mixer (stirrer) and dispersed by the mixer to obtain a slurry-like mixture. The aqueous solution of the polyvinyl alcohol is added to this mixture and mixed well. Further, the vinyl acetate emulsion is added and mixed. Further, calcium carbonate (Newlite F manufactured by Nitto Funka Kogyo Co., Ltd.) is added to this and mixed, and the viscosity is adjusted with purified water to obtain a white second liquid multi-agent.

[0033] An asparagus cultivation experiment was conducted in an asparagus field in the plains of Chiba Prefecture using the black first liquid multi-agent and the white second liquid multi-agent.

[0034] <Experimental Example 1> 〇 Confirmation Experiment on the Efficacy of Liquid Multi-Preparation First, an experiment was conducted on the efficacy of the formulated black first liquid multi-preparation. At the end of January, the field surface was burned with a gas burner and sterilized. On a fine day in mid-February, the formulated first liquid multi-preparation diluted with tap water was sprayed on the ridges using a power sprayer (AP200 manufactured by Kyoritsu Corporation) so that the spraying amount of the first liquid multi-preparation was 500 g / m 2 . As a comparative example, when the field was covered with a black poly film mulch with a thickness of 0.02 mm (manufactured by Tsujino Plastic Industry Co., Ltd.), and for the open field without any treatment, two ridges were prepared for each. One week later, a thermometer (Temperature Data Logger manufactured by Tian Du Di Co., Ltd.) was used to measure the ground temperature in the soil at a depth of 15 cm from the ground surface over time. The ground temperature change situation is shown in the table diagram of Fig. 1. In the table diagram, since the experiment was conducted on two ridges for each, it is denoted as First Liquid Multi-Preparation I, II, Poly Film Mulch I, II, Untreated I, II. From this result, it was confirmed that the first liquid multi-preparation showed a temperature change comparable to that of the conventional one using a poly film mulch, and in particular, it has the effect of preventing the temperature drop in the soil at night. After that, in the field where the poly film mulch was applied, since the germination of asparagus was expected, when the poly film mulch was removed, the ground temperature drop was observed to be the same as that of the untreated one. It was confirmed that the heat preservation effect was obvious for those using the first liquid multi-preparations I and II that do not require the removal of the coating film by applying the first liquid multi-preparation.

[0035] 〇 Confirmation Experiment on the Effect of the Coating Film of the First Liquid Multi-Preparation Next, in the same field as in Experimental Example 1, two test plots with the first liquid multi-preparation applied and two control plots without any treatment were further divided into ridges with irrigation and ridges without irrigation, and the harvesting situation of asparagus was examined. In each ridge, 10 plants of asparagus rhizomes were planted. The experimental period is the effective period of the coating film formed by the first liquid fertilizer until the upright stems grow from March to May. For the harvested asparagus, the thickness of the harvested asparagus for each underground stem (plant) is classified into 7 ranks: "2L", "L thick", "L thin", "M", "S", "B" (low quality), and "out of specification", which are in accordance with the asparagus shipping standards in the area. The average weight (g / plant) of asparagus in each rank and the total of the average weights are taken as the total weight (g), and the results are shown in the graph in Table 2. In the test plot where the coating film of the first liquid fertilizer was formed, asparagus germination was confirmed from early March. In contrast, in the untreated control plot where no fertilizer was applied, asparagus germination was gradually confirmed around the second half of mid-March. This is judged to be the result that the test plot with the coating film of the first liquid fertilizer has a better ground temperature increase and heat preservation effect than the untreated control plot, and early germination was achieved as confirmed in Experimental Example 1.

[0036] As is clear from the graph in Table 2, the average weight per underground stem of asparagus in the test plot with the coating film of the first liquid fertilizer is superior to the yield in the untreated control plot in most cases with irrigation and non-irrigation from 2L to M size. It was confirmed that the asparagus grown in the test plot with the coating film of the first liquid fertilizer grew vigorously. When observing the difference between irrigation and non-irrigation, it is confirmed that the average weight is heavier for those with irrigation, indicating that irrigation is important. For the test plot with the coating film of the first liquid fertilizer, even in the case of non-irrigation, in most cases with S size or above, the average weight is heavier compared to the untreated irrigated and non-irrigated ridges. As a result, in the test plot with the coating film of the first liquid fertilizer, the water retention effect function of the coating film works, and it was confirmed that even in non-irrigated ridges, asparagus can be harvested more vigorously than in the untreated irrigated control plot. Furthermore, it was confirmed that the stem diameter of the asparagus growing in the ridges with the coating film of the first liquid fertilizer is thicker than that of the untreated control plot, and it grows as a strong cultivated plant with good leaf attachment.

[0037] From the above, in the test plot with the coating film of the first liquid fertilizer, when exposed to sunlight, the soil temperature rises to 15°C or higher, and it has an excellent moisture retention effect. As a result, in seasons when the average temperature from March to May does not reach 22°C, it promotes the early germination of asparagus, and moreover, it was confirmed that the harvested asparagus can have a thick stem diameter, be strong, and have a firm and heavy weight.

[0038] <Experimental Example 2> Next, the effect of preventing the onset of stem blight of the second liquid fertilizer was investigated. In this experiment, two additional ridges with the coating film of the first liquid fertilizer were separately prepared. For these two ridges, the harvesting of asparagus was stopped from the middle of April, and the germinated new shoots were allowed to grow into standing stems. Then, in early May when the asparagus had grown considerably, for the two ridges with the coating film of the first liquid fertilizer, after removing the remaining coating film of the first liquid fertilizer, it was divided into a test plot where the second liquid fertilizer was sprayed to form a white coating film and an untreated control plot where only the remaining coating film of the first liquid fertilizer was removed without spraying the second liquid fertilizer, and the onset state of stem blight was observed. The spraying amount of the second liquid fertilizer in the experimental ridge was 1000 g / m 2 And for the foliage part of the standing asparagus, it was also sprayed up to a height of approximately 15 cm from the field surface to be covered with the coating film of the second liquid fertilizer. Then, the occurrence situation of stem blight from late May to early August was confirmed, and the results are shown in the table figure of Figure 3. Incidentally, when the second liquid fertilizer was sprayed, no onset of stem blight was observed in the parent plants growing in any of the ridges.

[0039] The table figure of Figure 3 shows the measurement of the ground temperature (depth 15 cm) on the corresponding investigation days, as well as the respective investigation stem numbers, the number of stems with stem blight occurrence, and the incidence rate in the test plot with the coating film of the second liquid fertilizer and the control plot. Here, the number of stems with occurrence is the number of parent plants in which the onset is confirmed. Even if multiple locations on one parent plant are found to be diseased or the disease has occurred extensively (over a large area), the number of stems with occurrence is counted as "1".

[0040] From the above results, starting from the observation point in late May, approximately three weeks after coating with the second liquid multi-agent, the incidence rate of stem blight in the test plot is clearly lower than that in the control plot. However, the difference has been increasing over time. In early August, the incidence rate in Test Plot Y is 10.9%, while in the control plot, it exceeds seven times that, reaching 78.1%. It was confirmed that the second liquid multi-agent's coating film has a highly effective disease suppression effect on stem blight in the test plot where the coating film was formed. When growing in the spring stage with the coating film of the first liquid multi-agent formed, as shown in Experimental Example 1, due to the effects of increasing soil temperature, heat preservation, and water retention by coating with the coating film of the first liquid multi-agent, strong standing stems are formed. Also, since the temperature is sometimes lower than the reproduction temperature of the pathogen, the incidence rate of stem blight has been suppressed to a low level. However, the reason why the incidence rate of stem blight is higher in the control plot than in the test plot is presumably that, depending on the presence or absence of the coating film of the second liquid multi-agent, a large difference in the degree of attachment of the stem blight pathogen inhabiting the field surface by the splashing water associated with rainfall to the nursery stock occurs at an early stage, resulting in a difference in the incidence rate.

[0041] And thereafter, in the test plot where a white coating film was formed by the second liquid multi-agent, although the occurrence of stem blight cannot be completely suppressed, it was confirmed that there is a clearly significant difference compared to the incidence rate of stem blight in the control plot where no treatment was applied. This is because, by replacing the coating film from the black first liquid multi-agent to the white second liquid multi-agent, the effects of preventing abnormal increase in soil temperature and waterproofing are exerted, enabling temperature protection of the underground stem and sound growth. Even if there is scattering of the stem blight pathogen growing on the field surface into the air, as a result of the coating film being applied to the standing stem part, the attachment of the pathogen scattered in the air is suppressed. This not only suppresses the onset of the disease in the nursery stock itself but also suppresses the scattering of the pathogen due to the destruction of the pycnidia formed at the diseased part of the already diseased stem blight. Thus, not only for primary infection but also for secondary infection, a large suppression effect can be exerted, enabling the sound cultivation of asparagus.

[0042] Thus, in the present invention, in the initial stage of cultivation before germination, a coating film is formed with a black first liquid mulch agent, and when the average temperature approaches 22°C, a coating film is formed with a white second liquid mulch agent for asparagus cultivation. Robust asparagus growth can be obtained from early spring, and stable harvesting can be achieved at an early stage. Regarding the coating film of the second liquid mulch agent, by coating not only the surface of the standing stems but also the surface of the stems, it is possible to not only suppress the primary infection of stem blight but also the secondary infection, resulting in high yields each year and the suppression of the incidence of stem blight over the years, and it is expected that stable income can be achieved.

[0043] Incidentally, although the mulching method of the present invention has been described as being suitable for asparagus stem blight, it is presumed to be effective against diseases such as powdery mildew, white rust, black brown spot, brown spot, scab, anthracnose, rust, soft rot, sclerotinia, half-plane ginkgo disease, damping-off disease, etc., which are the same filamentous fungi as stem blight. In particular, it is considered effective for cucumbers and melons with vine blight, peppers, tomatoes, eggplants, etc. with leaf blight, and for cucurbitaceae, legumes, asteraceae, poaceae, etc. with brown spot. Furthermore, it is considered effective for the genus Cercospora, which causes diseases in plants in general, and for the genus Corynespora, which causes diseases in legumes, etc. However, these will be left for future research. In addition, regarding the biodegradable liquid mulch agent used in the present invention, by using colored liquid mulch agents added with various color pigments such as purple, blue, red, green, etc. instead of black and white pigments, it is possible to prevent damage caused by pests that avoid specific colors, and it is also expected to improve the coloring of the parts on the field side of vegetables and fruits by receiving specific light (specific reflected light) from the field side.

Industrial Applicability

[0044] The present invention can be used as a cultivation method for asparagus, which is eaten as a vegetable, and as a liquid mulch agent used in the cultivation method.

Claims

1. A method for cultivating asparagus, in which young shoots germinated from asparagus rhizomes in a field grow, and the young stems that have reached the harvest height are cut and harvested, comprising: Before the new shoots germinate from the rhizomes in early spring, a first liquid fertilizer containing a black pigment as one of the main components is sprayed on the field, and asparagus is cultivated with the field covered with a black coating film. Then, corresponding to the stem elongation period when the temperature rises, a second liquid fertilizer containing a white pigment as one of the main components is sprayed on the field, and asparagus is continuously cultivated with the field covered with a white coating film. A method for cultivating asparagus, characterized by the above.

2. The method for cultivating asparagus according to claim 1, wherein the spraying of the second liquid fertilizer is carried out when the temperature is 18°C to 25°C, preferably 22°C.

3. The method for cultivating asparagus according to claim 1, wherein the spraying of the second liquid fertilizer includes the foliage of the mother plants, and the surface of the foliage is covered with a coating film of the second liquid fertilizer.

4. The method for cultivating asparagus according to claim 3, wherein the height of the coating of the foliage surface with the second liquid fertilizer is 5 cm or more from the field surface.

5. The spraying of the second liquid fertilizer on the field may be repeated, and the repeated spraying of the second liquid fertilizer is carried out when more than 1 / 4 of the coating film of the previously sprayed second liquid fertilizer has disappeared. The method for cultivating asparagus according to claim 3, characterized by the above.

6. The coating of the foliage with the second liquid fertilizer may also be repeated other than when the second liquid fertilizer is repeatedly sprayed on the field. The repeated coating of the foliage with the second liquid fertilizer other than the repeated spraying on the field is carried out by spraying or applying to the foliage. The method for cultivating asparagus according to claim 3, characterized by the above.

7. The first liquid fertilizer is a black suspension emulsion aqueous solution mainly composed of a biodegradable polymer emulsion and a dispersant in addition to the black pigment. The second liquid fertilizer is a white suspension emulsion aqueous solution mainly composed of a biodegradable polymer emulsion and a dispersant in addition to the white pigment. A liquid fertilizer used in the method for cultivating asparagus according to claim 1, characterized by the above.

8. The liquid multi-agent used in the method for cultivating asparagus according to claim 7, characterized in that at least one kind of agent selected from herbicides or fungicides is mixed in the first liquid multi-agent and / or the second liquid multi-agent.

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