Rice and fish planting pond field co-culture method

Abstract

The invention discloses a rice and fish planting pond field co-culture method, which mainly comprises a larval crab culture technology and an adult crab culture technology, and relates to the aspects of rice field selection, field engineering, fry stocking, feed feeding, daily management and the like. Large-size one-year-old larval crabs are bred by taking measures such as low density, frequent water changing, early feeding, feeding regulation and control and molting promotion, a foundation is laid for breeding large-size river crabs, and a technical support is provided for guaranteeing supply of juvenile crabs bred in a rice field and improving the quality of the bred juvenile crabs.

Description

Technical Field

[0001] The invention relates to the technical field of agriculture and breeding, and more particularly to a rice-fish breeding pond-field co-cultivation method. Background Art

[0002] In existing agricultural practices, the crab-rice symbiotic farming model has been applied to a certain extent. This model forms an ecological cycle agricultural system by releasing crabs in rice fields, using the crabs' foraging activities to weed and loosen the soil, and using their excrement as natural fertilizer to promote rice growth. This farming method aims to reduce the use of chemical pesticides and fertilizers and improve the ecological value of agricultural products. However, traditional crab-rice symbiotic farming methods often lack systematic management and scientific regulation, which makes it difficult to accurately control the ecological balance between crabs and rice, thereby affecting the yield and quality of rice, as well as the growth rate and survival rate of crabs. It is mainly manifested in the following aspects: First, it is difficult to maintain ecological balance: In traditional methods, key parameters such as the number of crabs, stocking time, and feed delivery lack scientific basis, which can easily cause ecological imbalance in rice fields, such as excessive foraging of crabs affecting the rice root system, or poor rice growth affecting the living environment of crabs. Second, unstable yield and quality: Due to the lack of refined management, rice yield and crab quality often fluctuate greatly, making it difficult to achieve the best economic benefits. Moreover, in traditional rice field crab farming, the seedlings are small in size and poor in quality, and the size of adult crabs cannot meet market demand.

[0003] Therefore, how to provide a more efficient and high-quality crab-rice farming technology is an urgent problem to be solved by technicians in this field. Summary of the invention

[0004] In view of this, the present invention provides a high-quality and efficient technical model for crab-rice farming, which solves the problems of small seedling specifications, poor quality, and adult crab specifications that are difficult to meet market demand.

[0005] To achieve the above object, the present invention adopts the following technical solutions: A rice-fish farming pond-field co-cultivation method comprises the following steps: Step 1: Cultivating crabs in rice fields (1.1) Rice field transformation Select rice fields with strong water retention capacity, convenient drainage and irrigation, and unpolluted water sources, build dams around them, dig trenches 20 to 30 cm away from the water inlet ditches in the fields, and set up escape-proof walls after planting rice seedlings and before seedlings are placed; (1.2) Seedling placement Select healthy, fast-moving, uniform-sized, disease-free megalopause seedlings and stock them in late May or early June when the ammonia nitrogen concentration in the water is ≤2.0 mg / L. (1.3) Farming management Feeding: Start feeding compound feed after crab seedlings metamorphose into crab larvae. Before late July, feed once a day, and the amount of feed accounts for 3% to 5% of the total weight of the crabs; from late July to mid-August, feed once every two days, and the daily amount of feed accounts for 1% to 2% of the total weight of the crabs; 2 days before harvesting, feed 5% to 7% of the total weight of the crabs every week, and stop feeding when the crab gonads turn slightly yellow. Water quality control: Ensure that the dissolved oxygen concentration of paddy field water is ≥5.0 mg / L, pH 8.0-9.0, and change the water every 3-7 days; Disease prevention and control: timely remove leftover bait and dead crabs and carry out routine disease prevention and control; (1.4) Fishing When the crab fry grows to 100-200 per kg, they are caught and the crabs are obtained; Step 2: Raising crabs in rice fields (2.1) Field selection Select rice fields with good water retention, which will not be flooded in heavy rains or dry up in droughts, build dams around them, dig trenches 20 to 30 cm away from the water inlet ditches in the fields, and set up escape-proof walls after planting rice seedlings and before seedlings are placed in the rice fields; (2.2) Seedling placement Select one-year-old crabs with uniform size, strong vitality, intact limbs, no disease and shiny body color, and temporarily raise them during the rice seedling acclimatization period. After the rice seedlings have been slowed down and grow normally, release them into the rice fields after applying rice tillering fertilizer; (2.3) Farming management Feeding: Feed twice a day, morning and evening, with a daily feeding rate of 5% of the total crab weight. The morning feeding amount accounts for 30% of the daily feeding weight, and the evening feeding amount accounts for 70% of the daily feeding weight. Water quality control: In the early stage of stocking, the water level on the field is maintained at 10cm, and the water is changed once every 10 days; in the hot season, the water level on the field is maintained at 20cm, and the water is changed 1-2 times a week; the amount of water changed each time is one-third of the total water volume, and the water change time is ≤3h. The water temperature change in the rice field is ≤5℃, and the water is drained first and then the water is added; Field management: Avoid spraying fertilizers directly into the ditches when fertilizing crab fields, and do not apply more than 5kg / mu of heavy urea to rice fields. Disease prevention and control: timely remove leftover bait and dead crabs and carry out routine disease prevention and control; (2.4) Fishing and fattening Fishing starts when the crabs reach sexual maturity, and they are fattened for 1 to 2 weeks after being caught.

[0006] Preferably, the dam ridge in step (1.1) has a height of 50-60 cm, a dam top width of 50-60 cm, a ditch top width of 80-100 cm, a bottom width of 50-60 cm, and a depth of 50-60 cm, and the ditch accounts for no more than 10% of the rice field area.

[0007] Preferably, the anti-escape wall setting in step (1.1) is specifically as follows: A plastic film anti-escape wall is set up along the outer side of the dam ridge. The anti-escape wall forms a 70° angle with the field surface. The inlet and outlet of the rice field are set diagonally, drainage pipes are installed at the inlet and outlet, and anti-escape nets are added to the pipe openings.

[0008] Preferably, in step (1.2), the specification of large-eyed juvenile seedlings is 160,000 to 200,000 per kg, and the stocking amount is 0.125 to 0.25 kg per mu.

[0009] Preferably, the dam ridge in step (2.1) has a height of 50 to 80 cm, a dam top width of ≥50 cm, a ditch top width of 80 to 100 cm, a bottom width of 50 to 60 cm, and a depth of 50 to 60 cm, and the ditch accounts for no more than 10% of the rice field area.

[0010] Preferably, the anti-escape wall setting in step (2.1) is specifically as follows: A plastic film anti-escape wall is set up along the outer side of the dam ridge. The anti-escape wall forms a 70° angle with the field surface. The inlet and outlet of the rice field are set diagonally, drainage pipes are installed at the inlet and outlet, and anti-escape nets are added to the pipe openings.

[0011] Preferably, the specification of one-year-old crabs in step (2.2) is 120 to 160 crabs / kg, and the number of precocious individuals does not exceed 5%.

[0012] Preferably, the temporary rearing in step (2.2) adopts one or more of pond temporary rearing, enclosure field temporary rearing or ring ditch temporary rearing. Before entering the water for temporary rearing, the crabs are placed in pond water and soaked for 3-5 seconds and then taken out, and the process is repeated 2-3 times, each time with an interval of 3-5 minutes, and then the crabs are soaked and disinfected in a sodium chloride solution with a mass concentration of 3-5% for 5-10 minutes. During the temporary rearing period, the crabs are fed twice a day, and the daily feeding amount is 10% of the total weight of the crabs, with one-third of the daily feeding amount being fed in the morning and two-thirds of the daily feeding amount being fed in the evening.

[0013] Preferably, the pigs are immersed and disinfected before being released in step (2.2), and the release density is 260 to 400 per mu.

[0014] Preferably, during the fattening period in step (2.4), the water quality is kept fresh and natural feed is fed.

[0015] Specifically, the natural feed is animal feed and plant feed, wherein the animal feed accounts for 60% of the total weight, the plant feed accounts for 40% of the total weight, the natural feed feeding amount is 5% of the total weight of the crabs, and the fattening density is 1-2 kg / ㎡.

[0016] It can be seen from the above technical solutions that, compared with the prior art, the present invention discloses a method for co-cultivation of rice and fish in ponds and fields, which has the following beneficial effects: This technology cultivates crabs in the first year, and makes full use of the rice growing period to cultivate them in temporary ponds in the second year, striving to increase the crab size by 50% on the original basis during the two molting periods, solving the problem of small seedling size, poor quality, and adult crab size that cannot meet market demand. This technology has great room for development and great potential, and can play a great role in promoting the integrated rice-fish farming. DETAILED DESCRIPTION

[0017] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] This technology is used in Jilin Province, Liaoning Province, Heilongjiang Province and the eastern part of Inner Mongolia Autonomous Region. The following takes the western rice-growing area of ​​Jilin Province as an example.

[0019] The soil types in the rice-growing areas in western Jilin Province are all typical soda saline-alkali soils, which are suitable for the growth of river crabs, with fast growth and few diseases. They can also improve the salinity of rice fields, reduce pH values, and increase water fertility. The specific plans during the promotion process are as follows: 1. High-quality and efficient technology for breeding crabs in rice fields 1. Rice field transformation (1) Selecting fields Select rice fields with strong water retention capacity, convenient irrigation and drainage, and unpolluted water sources. The area of ​​the crab breeding unit is 5 to 20 mu, and the breeding unit area is preferably 10 to 50 mu.

[0020] (2) Field engineering Ridges are built around the field-breeding unit, with a dam height of 50 to 60 cm and a dam top width of no less than 50 to 60 cm.

[0021] Ditch pits are dug in the field 20 to 30 cm away from the water inlet ditch, with an upper width of 80 to 100 cm, a bottom width of 50 to 60 cm, and a depth of 50 to 60 cm. They are 20 to 30 cm away from the water inlet ditch. The ditch pits should account for no more than 10% of the area. Aquatic plants such as Elodea and Hydrilla verticillata should be planted in the crab ditches.

[0022] (3) Escape prevention facilities After the rice seedlings are planted in the rice field, an escape prevention wall is set up before the seedlings are released. A plastic film escape prevention wall is set up along the outside of the dam ridge, and a bamboo pole is inserted at intervals of 50 to 60 cm for support. The top of the bamboo pole is connected with a thin rope, and the thin rope is wrapped with the upper end of the plastic film to fix it. The lower end is buried 15 to 20 cm underground. The escape prevention wall is high, the inner wall is smooth, and it forms an angle of 70° with the field surface. The inlet and outlet are set up with diagonal inlet and outlet, and a 1.0 to 1.2 meter long injection and drainage pipe is buried, and an escape prevention net is added to the pipe mouth.

[0023] 2. Seedling placement (1) Selection of crab seedlings The big-eyed juvenile seedlings are strong, crawl quickly, uniform in size, and free of disease. The specification is 160,000 to 200,000 pieces / kg, which conforms to the requirements of GB / T 26435.

[0024] (2) Stocking crab fry The transportation of crab seedlings should comply with the provisions of GB / T 26435. At the end of May and the beginning of June, when the ammonia nitrogen concentration in the water is ≤2.0 mg / L, or the crab seedlings survive normally for 24 hours in the test water, megalopa larvae can be directly released at a stocking rate of 0.125-0.25 kg / mu.

[0025] 3. Breeding management (1) Feeding Feed compound feeds that meet the requirements of GB / T 13078 and NY / T 5072. Start feeding compound feeds after the crab seedlings metamorphose into crab larvae. Before late July, feed once a day, and the feeding amount accounts for 3% to 5% of the total weight of the crabs; from late July to mid-August, feed once every two days, and the daily feeding amount accounts for 1% to 2% of the total weight of the crabs; two days before harvesting, feed 5% to 7% of the total weight of the crabs every week, and increase or decrease the feeding amount according to the amount of leftover bait last time, and stop feeding when the crab gonads turn slightly yellow.

[0026] (2) Management Check once in the morning and evening to see if the escape prevention facilities are damaged, the amount of feed, the crab activity, the occurrence of diseases and insect pests, etc. If any problems are found, solve them in time. Eliminate pests such as rats and frogs.

[0027] (3) Water quality control While trying not to dry the fields, adopt the principle of shallow water in spring, full water in summer, and regular water changes. Keep the water level at 5 cm to 10 cm in spring and 15 cm to 20 cm in summer to ensure that the dissolved oxygen concentration is not lower than 5.0 mg / L and the pH is 8.0 to 9.0. Change the water every 3 to 7 days.

[0028] (4) Disease prevention and treatment Use disease prevention drugs and treat crab diseases in accordance with NY 5071. Focus on prevention and strictly control seedling disinfection and water disinfection. Remove leftover bait and dead crabs in a timely manner.

[0029] 4. Fishing In mid- to late September, crabs are harvested when they are active near the water. The methods include setting up ground traps in ditches, setting up traps in places that are convenient for operation and transportation, and waterproof fishing. The technical indicators of crab seedlings are 100 to 200 per kg, with uniform specifications. The yield is 40 to 60 kg per mu.

[0030] 5. Rice cultivation Select rice varieties with strong fertilizer tolerance, lodging resistance, disease resistance, and good rice quality, suitable for mechanized production and suitable environment. The seed quality should comply with the provisions of GB 8371. Fertilization should comply with the provisions of NY / T 496, NY / T 1105 and NY / T 2911. 2-3 days before transplanting, spray the seedlings with systemic insecticides. The use of drugs should comply with the provisions of GB / T 8321.2. Transplanting should be carried out mechanically in accordance with the provisions of NY / T 2192, and the row spacing should be set to facilitate the symbiosis of rice and crabs. Transplanting should be completed before the end of May. Pest and disease control should be carried out in accordance with the provisions of GB / T 8321.2, using high-efficiency, low-toxic, and low-residue pesticides for rice pest and disease control. After crab seeds are caught, rice is harvested mechanically.

[0031] (II) High-quality and efficient technology for breeding crabs in rice fields 1. Rice field transformation (1) Selecting fields Choose rice fields with good performance, which will not be flooded in heavy rains and will not dry up in droughts. The area of ​​the crab breeding unit should be 20 to 100 mu.

[0032] (2) Field engineering Ridges are built around the field-breeding unit, with a dam height of 50 to 80 cm and a dam top width of no less than 50 cm.

[0033] Ditch pits - dug in the field 20 to 30 cm away from the water inlet ditch, with an upper width of 80 to 100 cm, a bottom width of 50 to 60 cm, a depth of 50 to 60 cm, and a distance of 20 to 30 cm from the water inlet ditch. The ditch pits should not exceed 10% of the area.

[0034] (3) Escape prevention facilities After the rice seedlings are planted in the rice field, an escape prevention wall is set up before the seedlings are released. A plastic film escape prevention wall is set up along the outside of the dam ridge, and a bamboo pole is inserted at intervals of 50 to 60 cm for support. The top of the bamboo pole is connected with a thin rope, and the thin rope is wrapped with the upper end of the plastic film to fix it, and the lower end is buried 15 to 20 cm underground. The escape prevention wall is high, with a smooth inner wall, and forms a 70° angle with the field surface. Diagonal inlets and drainage outlets are set up, and 1.0 to 1.2 meters long injection and drainage pipes are buried, and escape prevention facilities are added to the pipe mouths.

[0035] 2. Selection of crab seedlings Select one-year-old crabs with uniform size, strong vitality, intact limbs, no disease and shiny body color. The size is 120-160 pieces / kg, and the number of precocious individuals should not exceed 5%.

[0036] Precocious individuals can no longer grow and are prone to death. Precocious female crabs have a round navel that covers the entire abdominal segment. There are many marginal hairs on the four sides of the navel, which are dark black in color. Precocious male crabs have a circle of bristles on their walking legs.

[0037] 3. Temporary breeding of crabs The crab seedlings are placed in the rice fields about 7 days after the rice seedlings are transplanted in early June and the rice seedlings have grown normally. During this period, they need to be temporarily raised. There are three main ways of temporary raising: pond temporary raising, field temporary raising, and ring ditch temporary raising. Before entering the water for temporary raising, put it in the pool water and soak it for 3 to 5 seconds, and repeat this 2 to 3 times, with an interval of 3 to 5 minutes each time, so that the crabs can adapt to the environment. Soak and disinfect it in a sodium chloride solution with a mass concentration of 3 to 5% for 5 to 10 minutes. After entering the pond, feed the crabs with feed, mainly special feed for river crabs, twice a day, and the daily feeding rate is about 10% of the total weight of the crabs; feed one-third of the daily feeding amount in the morning and two-thirds of the daily feeding amount in the evening, and adjust the feeding amount appropriately according to the eating situation. Change the water regularly and patrol the pond regularly every day to prevent escape.

[0038] (1) Temporary breeding in ponds Choose a pond with convenient water inlet and outlet, adjacent to the rice field, with an area of ​​5 to 10 mu. The pond should be more than 1m deep, and 60 to 80kg of crabs should be released per mu. Anti-escape facilities should be set up.

[0039] (2) Temporary breeding in enclosed fields The rice fields were transformed, with ridges 70-100cm high and 80-100cm wide at the top. A circular ditch was dug 60cm away from the ridge, with a width of 80-100cm and a depth of 50-80cm, and a slope of 1:1.5. Plastic film was used around to prevent escape, and a certain area was enclosed for temporary crab rearing. Covering materials were placed in the pond to facilitate crab molting. An area of ​​10-15 mu is appropriate, and the stocking density is 50-60kg / mu.

[0040] (3) Temporary breeding in a ring ditch Surround the ditch with plastic film as a temporary holding pond, and put about 80 kg per mu.

[0041] 4. Crab stocking and disinfection Stocking is carried out in early June. After applying rice tillering fertilizer, the crabs are put into the rice fields with a stocking density of 260 to 400 crabs per mu. Before stocking, they are soaked in 5% salt water for 5 to 10 minutes or in 20 mL / L potassium permanganate for 10 minutes.

[0042] 5. Feeding According to the nutritional needs of river crabs, special compound feeds for river crabs should be fed in stages. The feed quality should comply with the requirements of GB 13078 and NY 5072. The following four rules should be followed when feeding: Timing: Feed twice a day, once between 6 and 7 in the morning and once between 5 and 6 in the evening; Positioning: Feed at a fixed position each time, placing the feed on the field surface 30cm away from the ridge; Quality control: ensure that the feed is fresh and free of spoilage; Quantification: The daily feeding rate should be 5% of the total crab weight. The feeding amount should be adjusted in time according to the crab's eating habits every day. Feeding should be mainly done in the evening. The morning feeding amount accounts for 30% of the daily feeding amount, and the evening feeding amount accounts for 70% of the daily feeding amount.

[0043] 6. Water quantity and quality control In the early stage of stocking, the water level on the field is maintained at about 10 cm, and the water is changed once every 10 days; in the high temperature season, the water level on the field is maintained at 20 cm, and the water is changed 1 to 2 times a week; the amount of water changed each time is one-third of the total water volume, and the number and proportion of water changes are flexibly determined depending on the water quality in the field. The water change time is controlled within 3 hours, and the water temperature change in the rice field does not exceed 5°C. Generally, water is drained first and then added. New water is frequently added before and after river crabs molt. During the peak period of molting, water can be added appropriately without changing the water.

[0044] 7. Field management Observe changes in water quality, crab growth, whether the feeding situation is normal, whether there are dead crabs, and whether the ridges are leaking; check whether the escape prevention facilities are intact and whether the escape prevention nets at the inlet and outlet are damaged. If so, repair or replace them in time to prevent natural enemies such as water snakes, mice, frogs, and large birds from entering the fields. Note that drugs cannot be used to kill rodents.

[0045] Fertilization in crab fields should be carried out in accordance with the requirements of SC / T 1135.1. Chemical fertilizers should not be sprinkled directly into the crab ditch. Fertilization in rice fields should be done in small amounts and multiple times. The amount of urea applied each time should not exceed 5 kg / mu.

[0046] 8. Disease prevention and treatment Use disease control drugs and treat crab diseases in accordance with the provisions of NY 5071, focus on prevention, strictly control seedling disinfection and water disinfection, and remove leftover bait and dead crabs in a timely manner.

[0047] 9. Fishing Fishing begins in late August when the fish reach sexual maturity. You can use methods such as ground trap fishing, pit fishing, and light trapping. When operating, be careful to keep the appendages intact.

[0048] 10. Fattening After the river crabs are caught, they are fattened for 1 to 2 weeks depending on their fatness. During the fattening period, the water quality is kept fresh and the feed is natural. Specifically, animal feed (commercially available small crucian carp) and plant feed (corn) are used, with animal feed as the main feed (accounting for 60% of the total weight) supplemented by corn feed (accounting for 40% of the total weight). The daily feeding amount of natural feed is 5% of the total weight of the crabs, and the fattening density is 1 to 2 kg / ㎡.

[0049] After the implementation of the above-mentioned technologies, the average yield of crabs cultured in rice fields in western Jilin Province is 38kg per mu, with an average size of 10-17g, accounting for 65% of the total output, and an average increase of 1,450 yuan per mu; the average yield of adult crabs cultured in rice fields is 12kg per mu, with an average size of 110g, an average increase of more than 50% over the previous average, and an average increase of 1,331 yuan per mu; the amount of fertilizer applied is reduced by more than 20%, and the amount of pesticide applied is reduced by 2 / 3. At the same time, this technology has biological and ecological effects such as weed control, pest control, disease prevention, inter-tillage ventilation, and fertilization and root promotion. During the entire breeding process, the feeding, metabolism and movement of river crabs have different degrees of influence on the physical and chemical parameters of paddy field soil such as bulk density, pH, total nitrogen and total phosphorus.

[0050] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same and similar parts between the embodiments can be referred to each other. The above description of the disclosed embodiments enables professionals and technicians in this field to implement or use the present invention. Various modifications to these embodiments will be obvious to professionals and technicians in this field, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown in this article, but will comply with the widest range consistent with the principles and novel features disclosed herein.

Claims

1. A rice-fish farming pond-field co-cultivation method, characterized in that: The following steps are involved: Step 1: Cultivating crabs in rice fields (1.1) Rice field transformation Select rice fields with strong water retention capacity, convenient irrigation and drainage, and unpolluted water sources, build dams around them, dig trenches 20 to 30 cm away from the water inlet ditches in the fields, and set up escape-proof walls after planting rice seedlings and before seedlings are placed; (1.2) Seedling placement Select healthy, fast-moving, uniform-sized, disease-free megalopause seedlings and stock them in late May or early June when the ammonia nitrogen concentration in the water is ≤2.0 mg / L. (1.3) Farming management Feeding: Start feeding compound feed after crab seedlings metamorphose into crab larvae. Before late July, feed once a day, and the amount of feed accounts for 3% to 5% of the total weight of the crabs; from late July to mid-August, feed once every two days, and the daily amount of feed accounts for 1% to 2% of the total weight of the crabs; 2 days before harvesting, feed 5% to 7% of the total weight of the crabs every week, and stop feeding when the crab gonads turn slightly yellow. Water quality control: Ensure that the dissolved oxygen concentration of paddy field water is ≥5.0 mg / L, pH 8.0-9.0, and change the water every 3-7 days; Disease prevention and control: timely remove leftover bait and dead crabs and carry out routine disease prevention and control; (1.4) Fishing When the crab fry grows to 100-200 per kg, they are caught and the crabs are obtained; Step 2: Raising crabs in rice fields (2.1) Field selection Select rice fields with good water retention, which will not be flooded in heavy rains or dry up in droughts, build dams around them, dig trenches 20 to 30 cm away from the water inlet ditches in the fields, and set up escape-proof walls after planting rice seedlings and before seedlings are placed in the rice fields; (2.2) Seedling placement Select one-year-old crabs with uniform size, strong vitality, intact limbs, no disease and shiny body color, and temporarily raise them during the rice seedling acclimatization period. After the rice seedlings have been slowed down and grow normally, release them into the rice fields after applying rice tillering fertilizer; (2.3) Farming management Feeding: Feed twice a day, morning and evening, with a daily feeding rate of 5% of the total crab weight. The morning feeding amount accounts for 30% of the daily feeding weight, and the evening feeding amount accounts for 70% of the daily feeding weight. Water quality control: In the early stage of stocking, the water level on the field surface is maintained at 10cm, and the water is changed once every 10 days; In the hot season, the water level on the field surface is maintained at 20cm, and the water is changed 1-2 times a week; the amount of water changed each time is one-third of the total water volume, and the water change time is ≤3h. The water temperature change in the rice field is ≤5℃, and the water is drained first and then the water is added; Field management: Avoid spraying fertilizers directly into the ditches when fertilizing crab fields, and do not apply more than 5kg / mu of heavy urea to rice fields. Disease prevention and control: timely remove leftover bait and dead crabs and carry out routine disease prevention and control; (2.4) Fishing and fattening Fishing starts when the crabs reach sexual maturity, and they are fattened for 1 to 2 weeks after being caught.

2. A rice-fish farming method according to claim 1, characterized in that: The dam described in step (1.1) has a dam height of 50-60 cm, a dam top width of 50-60 cm, a ditch top width of 80-100 cm, a bottom width of 50-60 cm, and a depth of 50-60 cm. The ditch accounts for no more than 10% of the rice field area.

3. The rice-fish farming method according to claim 1, characterized in that: The anti-escape wall settings described in step (1.1) are as follows: A plastic film anti-escape wall is set up along the outer side of the dam ridge. The anti-escape wall forms a 70° angle with the field surface. The inlet and outlet of the rice field are set diagonally, drainage pipes are installed at the inlet and outlet, and anti-escape nets are added to the pipe openings.

4. The method for cultivating fish species in ponds and fields according to claim 1, characterized in that: In step (1.2), the specification of large-eyed juvenile seedlings is 160,000 to 200,000 pieces / kg, and the stocking amount is 0.125 to 0.25 kg / mu.

5. The method for cultivating fish species in ponds and fields according to claim 1, characterized in that: The dam ridge described in step (2.1) has a height of 50 to 80 cm, a dam top width of ≥ 50 cm, a ditch top width of 80 to 100 cm, a bottom width of 50 to 60 cm, and a depth of 50 to 60 cm. The ditch accounts for no more than 10% of the rice field area.

6. The method for cultivating fish species in ponds and fields according to claim 1, characterized in that: The anti-escape wall settings described in step (2.1) are as follows: A plastic film anti-escape wall is set up along the outer side of the dam ridge. The anti-escape wall forms a 70° angle with the field surface. The inlet and outlet of the rice field are set diagonally, drainage pipes are installed at the inlet and outlet, and anti-escape nets are added to the pipe openings.

7. The method for cultivating fish species in ponds and fields according to claim 1, characterized in that: In step (2.2), the size of one-year-old crabs is 120-160 pieces / kg, and the number of precocious individuals shall not exceed 5%.

8. The method for cultivating fish species in ponds and fields according to claim 1, characterized in that: The temporary rearing in step (2.2) adopts one or more of pond temporary rearing, enclosure temporary rearing or ring ditch temporary rearing. Before entering the water for temporary rearing, the crabs are placed in the pond water and soaked for 3-5 seconds and then taken out, and the process is repeated 2-3 times, each time with an interval of 3-5 minutes, and then the crabs are soaked and disinfected in a sodium chloride solution with a mass concentration of 3-5% for 5-10 minutes. During the temporary rearing period, the crabs are fed twice a day, and the daily feeding amount is 10% of the total weight of the crabs, with one-third of the daily feeding amount being fed in the morning and two-thirds of the daily feeding amount being fed in the evening.

9. The method for cultivating fish species in ponds and fields according to claim 1, characterized in that: In step (2.2), the fish are immersed and disinfected before release, and the release density is 260 to 400 per mu.

10. The method for cultivating fish species in ponds and fields according to claim 1, characterized in that: During the fattening period described in step (2.4), the water quality is kept fresh, and the feed is natural feed, which includes animal feed and plant feed, wherein the animal feed accounts for 60% of the total weight, the plant feed accounts for 40% of the total weight, the natural feed feeding amount is 5% of the total weight of the crab, and the fattening density is 1-2 kg / ㎡.