Rice-crab-double shrimp quaternary collaborative planting and breeding method and system

Abstract

The invention relates to the technical field of rice and fish comprehensive planting and breeding, in particular to a rice-crab-double shrimp quaternary collaborative planting and breeding method and system. The method specifically comprises the steps that an L-shaped or concentric-square-shaped circular ditch and a pit pond are constructed in a rice field, and an escape-proof facility, an independent water inlet and drainage system and a water pushing type oxygenation device are arranged; river crabs, freshwater shrimps and macrobrachium rosenbergii are stocked according to a time sequence, and ecological niche complementation and synergistic interaction among different species are realized in combination with aquatic plant planting and water quality regulation and control. By adjusting the water level and feeding at regular time, the stability of dissolved oxygen and the pH value of the water body is ensured, and the competitive relationship between organisms is optimized. The method can significantly improve the comprehensive output and economic benefits of the rice field, reduces the use of pesticides, improves the water quality, and has good ecological benefits and popularization values.

Description

Technical Field

[0001] This invention relates to the field of integrated rice-fish farming technology, and in particular to a method and system for the four-element synergistic farming of rice, crab, and shrimp. Background Technology

[0002] Rice-fish integrated farming has developed into several mature models in my country, among which "rice-crab symbiosis" and "rice-shrimp co-cultivation" are the most representative. Early rice-crab technologies achieved synergistic benefits through the engineering transformation of paddy fields (digging ring ditches / ponds, setting up escape-prevention facilities and independent water inlet and drainage) combined with crab seedling release and field management, resulting in "rice raising crabs and crab promoting rice growth." For example, Chinese patent (CN106688746A) "A method for rice-crab symbiosis" proposes a complete process including paddy field inlet and outlet channels and isolation nets, pre-transplanting disinfection, crab hiding places, and crab seedling management, constructing a small ecosystem of water, rice, crabs, and aquatic plants to reduce the input of chemical fertilizers and pesticides. Furthermore, Chinese patent (CN106982687B) "A method for rice-crab symbiosis" further integrates pond / paddy field transformation, crab seedling cultivation, and field management, emphasizing the complementary use of various aquatic organisms and crops to improve safety and yield. Regarding engineering elements, Chinese patent (CN103782940B) proposes that the area of ​​paddy field ditches should be controlled within 10% of the total area of ​​the field, and that they should be equipped with independent inlet and outlet drainage and escape prevention nets with a certain mesh size, so as to take into account both the cultivated area and the buffer volume for aquaculture.

[0003] In the rice-crayfish farming sector, existing technologies are continuously being improved around the chain of "rice paddy selection and modification—seedling stocking—feeding management—coordination with rice cultivation sequence." Chinese patent (CN106718451A), "A method for co-cultivating rice and crayfish," proposes to achieve "one rice, two crayfish" based on "rice-crayfish rotation," extending the crayfish's growth period in the rice paddy to achieve double harvests in one season, significantly improving overall benefits. Chinese patent (CN107549072A), "Rice-crayfish farming method," refines the geometric parameters of ditches (ditch depth, width, and layout), the proportion of broodstock crayfish, and supporting aquatic plants to facilitate centralized management and efficient harvesting. Regarding rice paddy facilities and water environment control, Chinese patent (CN111543362A), "Crab-rice co-cultivation pond and its comprehensive temperature regulation method," proposes key points for seasonal temperature regulation and dissolved oxygen management from the perspectives of water exchange frequency and temperature difference control, to balance the growth needs of both crabs and rice.

[0004] Regarding the rice-field coupling of giant freshwater prawns, Chinese patent (CN108719155A) provides a complete process from rice field preparation, pre-stocking treatment, prawn stocking, feeding, aquaculture management to harvesting, emphasizing the eco-friendliness and economic benefits of "giant freshwater prawn × rice". However, such solutions are mostly binary scenarios (rice and giant freshwater prawns), and rarely involve the coordinated temporal design and engineering parameter linkage with river crabs and freshwater prawns in the same rice field unit.

[0005] In summary, existing technologies provide element-level methods for rice-crab co-culture, rice-shrimp co-cultivation, and paddy field engineering parameters, temperature regulation, and oxygenation. However, they lack a systematic combination and parameterized window for the spatiotemporal coordination of river crabs, freshwater shrimp (in staggered cropping), giant freshwater prawns, and late-season rice within the same paddy field unit (e.g., coupling of ditch-field water exchange under low ditch area ratio conditions, filtration mesh size, and molting / feeding windows for multiple species). This leaves a technological gap to be addressed in achieving a "four-element synergistic farming" model that balances stable rice yield, ecological stability, and high-efficiency multi-species production while ensuring controllable management and facility economics. Summary of the Invention

[0006] The technical objective of this invention is to address the problems in existing rice-fish integrated farming models, such as the limitation to a binary structure of "rice-crab" or "rice-shrimp", low species utilization rate, insufficient water exchange and dissolved oxygen regulation, and unreasonable spatial configuration and temporal coordination. This invention proposes a four-element synergistic rice-crab-dual-shrimp farming method and system. By optimizing the ratio of paddy field ditches and pits, configuring independent water inlet and drainage systems and water-push aeration devices, and combining staggered release of freshwater shrimp with seasonal introduction of giant freshwater prawns, this invention achieves efficient utilization of paddy field space and time resources, thereby improving the comprehensive output, stability, and economic benefits of the rice-fish ecosystem.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A rice-crab-shrimp quaternary co-culture method is implemented according to the following temporal and spatial configuration: S1) Construct L-shaped or U-shaped ring ditches and / or ponds within the paddy field. The total area of ​​the ring ditches and / or ponds is ≤10% of the paddy field area. The water depth is 0.8-1.2m, the slope ratio is 1:3 to 1:2, and anti-escape boards are installed on the inner side of the field ridges. An independent water inlet and drainage system is set up, and filter screens are installed at the inlet and outlet. S2) After cleaning and disinfecting the pond, aquatic plants are laid in the surrounding ditches and / or pits to achieve a coverage of 50-60% of the paddy field area, and a water-pushing aeration device is installed to promote water exchange between the ditch and the paddy field. S3) In January and February, release river crab larvae and freshwater shrimp larvae into the surrounding ditches and / or ponds. The river crab larvae should be 80-120 per kg, with a density of 600-1200 per mu. The freshwater shrimp larvae should be 800-1200 per kg, with a density of 10-20 kg per mu. Maintain a high water level, do not apply pesticides throughout the process, and feed the shrimp and crabs daily at 1-3% of their body weight. S4) From late May to early June, select fertilizer-tolerant and lodging-resistant varieties for machine transplanting. After the soil turns green, raise the water level, do not dry the field or apply pesticides throughout the process, and complete the harvest in October-November. S5) Choose one of the following modes to operate: Model 1: In July-August, a second crop of freshwater shrimp is raised at a density of 4,000-8,000 shrimp / kg, or 10-20 kg / mu. Mode 2: After the crabs and shrimp have been harvested and disinfected, release 300-600 giant freshwater prawns per kg, or 10-20 kg per mu, from late June to early July; S7) Through water-pushing aeration and water level management, the dissolved oxygen in the ring ditch and / or pit is ≥5mg / L and the pH is 7.5-9.0. Feeding is carried out according to the principles of timed, quantitative, quality and location, and combined with microecological preparations. S8) Prawns, giant freshwater prawns, and river crabs are harvested in batches according to their growth rhythms.

[0008] As a preferred option Model 1: The first batch of prawns is released in late January and harvested in early March; the second batch is released in mid-to-late July and harvested in mid-to-late September; the river crabs are harvested in late October. Model 2: Before rice planting, catch river crabs and prawns, disinfect ditches and pits by splashing quicklime, release giant freshwater prawns in late June and harvest them in mid-to-late September; harvest river crabs in mid-to-late May.

[0009] Preferably, the escape-proof plate is made of plastic plate, thickened film or aluminum plate, buried at a depth of 15cm, with a height of 45-50cm above the ground, and the four corners are rounded and support piles are set every 0.8-1.0m.

[0010] As a preferred embodiment, the water inlet and outlet system includes: the water inlet is located at the bottom of the escape prevention facility and is made of PVC or cement pipe with a diameter of 20-30cm; the outlet is located at the lowest point of the pond and opposite the water inlet and is made of PVC or cement pipe with a diameter of 20-40cm. Both the inlet and outlet are covered with 80-mesh escape prevention net bags.

[0011] Preferably, the installed power of the water-pushing aeration device is configured to be ≥0.2kW / mu, and it is turned on in hot or cloudy / rainy weather to enhance the water exchange and cooling effect between ditches and fields.

[0012] Preferably, the aquatic plants are a combination of Elodea nuttallii and Hydrilla verticillata: Elodea nuttallii is transplanted in January-February to cover the surrounding ditches and / or ponds, maintaining a water level of 20-30cm, using the plant transplanting method, with a fresh plant quantity of 50-100kg per mu; Hydrilla verticillata is sown in the production ditches in February-March, maintaining a water level of 20-30cm, with a quantity of 5-10kg per mu; and the coverage is maintained at 50-60% by cutting or replanting.

[0013] As a preferred method, disinfect the pond with quicklime 30 days before planting aquatic plants, using 50-75 kg per acre, and evenly sprinkle it throughout the pond after it has been slurried.

[0014] As a preferred method, a combination of complete formulated feed and fresh fish soft pellets is used for feeding, with the feed being 1-3% and 5-8% of the shrimp and crab body weight respectively per day, and feeding should be done after 16:00, ensuring that no feed is left overnight.

[0015] As a preferred option, bird-proof facilities with a height of 2m or more should be installed, while also ensuring clearance for harvesters to pass through.

[0016] For optimal results, the rice varieties selected are Yongyou 1540, Zhejing 100, or Nanjing 46. The seedlings should be transplanted from late May to early June, preferably using machine transplanting. The row and plant spacing for conventional rice is 30cm × 25cm, and for hybrid rice it is 35cm × 30cm.

[0017] Furthermore, the present invention also provides a rice-crab-shrimp quaternary co-culture system for implementing the method, comprising: The paddy field hydraulic structure consists of L-shaped or loop-shaped ditches and / or ponds, with the total area of ​​the ditches / ponds ≤ 10% of the paddy field area, water depth 0.8-1.2m, and slope ratio 1:3 to 1:2; Escape prevention and enemy prevention devices: Escape prevention boards are laid along the field ridges and bird-proof netting is installed above the rice fields; Independent inlet and outlet drainage and escape-proof filtration components: equipped with inlet and outlet pipes and an 80-mesh filter bag; The water-push type aeration device and its power supply circuit; Aquatic plant habitat; Feeding and feeding locations and fixed traps for catching fish; The system forms a controllable water circulation channel at the ditch-field interface, enabling directional exchange between the water in the ditch / pit and the water in the rice plant area. This maintains dissolved oxygen and temperature gradients under pesticide-free rice management conditions, matching the synergistic growth needs of the four species.

[0018] This invention, by employing the aforementioned technical solutions, achieves three-dimensional utilization of paddy field space and time, as well as ecological niche complementarity. Specifically, by controlling the area of ​​ditches and pits to within 10% of the total paddy field area and using a push-type aeration device, a ditch-field water cycle is formed, improving the dissolved oxygen and temperature balance of the paddy field water, thereby significantly reducing stress and disease risks during multi-species co-cultivation. Through the staggered intercropping of freshwater shrimp and the seasonal introduction of giant freshwater prawns, the various species in the paddy field do not compete with each other at different water layers and growth stages, forming a stable energy and nutrient cycle. At the same time, rice plants absorb nitrogen and phosphorus elements from shrimp and crab metabolites, realizing the secondary utilization of feed resources, reducing the application of chemical fertilizers and pesticides, and improving rice quality and ecological benefits. Comprehensive results show that, while maintaining a rice yield of over 500 kg per mu, this invention achieves a 20-30% increase in total shrimp and crab yield, a profit increase of over 40%, and significantly improves the water quality and biodiversity of the paddy field ecosystem. Attached Figure Description

[0019] Figure 1 It is in the form of paddy field ditches. Figure 1 In the middle, A is an L-shaped groove. Figure 1 In the middle, B is a loop-shaped groove. Figure 1 C represents a pit or pond. Detailed Implementation

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present invention.

[0021] I. Paddy Field Conditions (I) Rice paddy transformation An area of ​​5-30 mu (approximately 0.33-0.67 hectares) is ideal. If the plot is too small, the surrounding ditch will be narrow, making it unsuitable for planting aquatic plants and placing aeration equipment. If the plot is too large, it will hinder feeding and management. Figure 1 As shown, the paddy fields should be laid out in L-shaped, U-shaped, or pit-pond configurations. The size of the surrounding ditches and pits should not exceed 10% of the paddy field area, with a water depth of 0.8m-1.2m. The slope of the ditches and pits should be 1:3-1:2, and double-layer slope protection using mulch film and polyethylene mesh can be used. The paddy fields should be flat and have good water retention. The width of the field ridges within the escape-proof boards should be 0.5m-1.5m, and the ridges should be firm and leak-proof. It is also advisable to appropriately deepen and widen the sub-ditches to increase the activity range of shrimp and crabs.

[0022] (ii) Escape prevention facilities Escape prevention facilities should be set up on the pond embankment. Plastic boards, thickened thin films, or aluminum plates can be used. They should be buried 15cm deep in the soil and 45cm-50cm above the embankment surface. The outer side should be supported by wooden stakes, bamboo poles, or cement stakes every 0.8m-1m. The escape prevention facilities at the four corners of the pond should be in an arc shape.

[0023] (III) Defensive Facilities To prevent birds and other natural enemies from entering, bird protection facilities, such as bird nets or wires, must be installed, with a height of 2 meters or more, or at the height of a harvester.

[0024] (iv) Inlet and Drainage System Each paddy field should have an independent water inlet and drainage system. The water inlet should preferably be a pipe, either open or culvert, with the inlet located below the escape-prevention facilities. When crossing the pond embankment, a 20-30cm diameter PVC or cement pipe should be used, and the pipe opening should be wrapped with a 0.32mm (80 mesh) silk netting bag. The drainage outlet should be located at the lowest point of the pond, opposite the inlet, using a 20-40cm diameter PVC or cement pipe, with an escape-prevention net installed at the end.

[0025] (v) Aeration equipment It is recommended to use a push-type aerator, which can promote sufficient exchange of water between the ditches and pits and the rice planting area, increase the oxygen content of the water in the rice planting area, and reduce the water temperature in the ditches and pits, thus fully leveraging the advantages of the model. Each acre of water area should be equipped with a power of at least 0.2 kW.

[0026] II. Rice Selection and Cultivation (I) Variety selection and planting For rice cultivation, select superior varieties that are tolerant of fertilizer, pests and diseases, lodging-resistant, and have a long growing season, such as Yongyou 1540, Zhejing 100, and Nanjing 46. Transplant the prepared seedlings from late May to early June, preferably using machine transplanting. The row spacing for conventional rice is 30cm x 25cm, and for hybrid rice, it is 35cm x 30cm.

[0027] (II) Rice Management The rice is managed according to local traditional rice cultivation methods. After the rice turns green, the water level is raised, and the field is not dried out or pesticides are applied throughout the process. Topdressing can be applied appropriately according to the rice growth. The rice is harvested manually or mechanically after it matures from late October to mid-November.

[0028] III. Shrimp and Crab Farming Management (a) Preparations before releasing the animals 1. Disinfection Drain the water from ditches and pits, and level the fields, ditches, and pits. Remove excess silt and check escape prevention measures. Disinfect the pond with quicklime 30 days before planting aquatic plants, using 50-75 kg per acre, and evenly sprinkle it throughout the pond after it has been slurried.

[0029] 2. Aquatic plant cultivation Before planting aquatic plants, apply base fertilizer, using approximately 5-10 kg of compound fertilizer per mu (approximately 0.067 hectares), or add bio-fertilizer. The aquatic plants should cover 50%-60% of the paddy field area. From January to February, plant *Elodea nuttallii* in ditches and pits, maintaining a water level of 20-30 cm, using the transplanting method, with 50-100 kg of fresh plants per mu. From February to March, sow *Hydrilla verticillata* buds in the paddy field furrows, maintaining a water level of 20-30 cm, using approximately 5-10 kg per mu.

[0030] (II) Seedling Release 1. Release of crab seedlings Select high-quality breeds with complete appendages, no disease spots, no rotten limbs or claws, and clean gills. The size should be 80-120 birds / kg, with uniform size. The stocking density should be 600-1200 birds per mu (approximately 0.16 acres). Stocking should be done in January or February, with a water temperature of 4℃-10℃ being ideal.

[0031] 2. Release of freshwater shrimp fry After releasing the crab larvae, release the freshwater shrimp larvae, with a size of 800-1200 shrimp / kg and a stocking density of 10-20 kg per mu. If it is mode one (Table 1), from mid-July to early August, release a second crop of freshwater shrimp (self-bred larvae, requiring a matching pond), with a size of 4000-8000 shrimp / kg and a stocking density of 10-20 kg per mu, to achieve multiple crop farming and increase yield.

[0032] 3. Release of Giant Freshwater Prawn Seedlings Before rice planting, catch river crabs and freshwater shrimp, and disinfect ditches and pits by spraying quicklime. From mid-June to early July, release giant freshwater prawn larvae at a size of 300-600 prawns / kg, with a stocking density of 10-20 kg per mu (approximately 667 square meters). Choose a time with good weather for stocking, avoiding transportation and stocking during peak molting periods to minimize stress.

[0033] Table 1. Shrimp and Crab Seedling Release and Harvesting

[0034] (III) Daily Management 1. Water quality management Maintain dissolved oxygen levels in ditches and pits at no less than 5 mg / L and pH values ​​between 7.5 and 9.0. Regularly administer calcium supplements and probiotics every 10-15 days. During hot or rainy weather, promptly activate air-lift aerators to increase dissolved oxygen and water exchange, preventing water quality deterioration.

[0035] 2. Aquatic plant management Based on the growth of aquatic plants in ditches and pits, appropriately cut off overly dense aquatic plants or replant missing parts to maintain a reasonable density of aquatic plants and provide a good habitat for shrimp and crabs.

[0036] 3. Feeding Management Scientific feeding should adhere to the four fixed principles. The daily feeding rate of complete formulated feed should be 1%-3% of the shrimp and crab's body weight, and fresh fish soft pellets should be 5%-8%, adjusted appropriately according to water temperature, size, water quality, and weather. Feeding should begin after 4 PM, and the feeding situation should be checked daily, ensuring no uneaten feed remains overnight. An appropriate amount of microecological preparations can be added to the feed to improve the shrimp and crab's immunity.

[0037] 4. Capture Fishing times are shown in Table 1. Fixed ground cages are used as fishing tools.

[0038] 5. Disease prevention and control Adhering to the principle of "prevention first, combined with treatment," ecological disease prevention measures are implemented, including pond cleaning and disinfection, stocking healthy seedlings, planting aquatic plants in ditches and pits, regularly using microecological agents, and feeding fresh, high-quality feed.

[0039] To verify the technical effectiveness of the quaternary synergistic farming method and system of "crab-prawn-late rice-Macrobrachium rosenbergii" (hereinafter referred to as "this invention"), a comparative experiment was conducted in the same nursery area in Huzhou, Zhejiang Province. All experimental plots shared the same water source, climate, and management team. The soil was loamy clay with a topsoil content of 28-32 g / kg organic matter and a pH of 6.7-7.1. Three parallel plots (n=3) were set up for each treatment of each experimental project, each plot measuring 10-20 mu (approximately 6.7-13.3 hectares). The statistical period was from January to November of the same year. Unless otherwise specified, parameters not measured were performed according to conventional fishery / rice farming methods.

[0040] I. Common and General Conditions Pond cleaning and bottom improvement: Drain the water from the ditches and pits, leaving 50-10cm of silt; slurry 500-75kg / mu of quicklime is dissolved and sprinkled throughout the pond; after standing for 5-7 days, the water is replenished to 30cm.

[0041] Aquatic plants: Elodea nuttallii (transplanted in January-February, 50-100 kg / mu), Hydrilla verticillata (buds 5-10 kg / mu in February-March). The planting area of ​​Elodea nuttallii and Hydrilla verticillata is calculated according to the area of ​​ditches, pits and production ditches, and the coverage is maintained at 50-60%.

[0042] Late rice: Machine transplanting from late May to early June, conventional rice 30×25cm, hybrid rice 35×30cm; water level 20-25cm after greening, no chemical pesticides applied throughout the process.

[0043] Water quality targets: DO ≥ 5 mg / L, pH 7.5–9.0, transparency 25–35 cm; ammonia nitrogen and nitrite will be tested weekly.

[0044] Feeding: Feed at fixed points after 16:00; 1-3% of body weight of formulated feed and 5-8% of body weight of fresh fish soft pellets; "No leftover feed overnight".

[0045] II. Processing Settings Example 1 (Mode 1: Quadrivalent-Two-Crop Shrimp) Engineering and Equipment: The area of ​​the ring ditch / pond should be ≤10%, the water depth should be 0.9-1.0m, and the slope ratio should be 1:3 to 1:2; independent inlet and outlet (20-30 / 20-40cm pipe diameter), with 80-mesh net bags installed at both inlet and outlet; push-type aeration ≥0.25kW / mu, with the impeller facing the rice-growing area to form a "ditch → field → ditch" circulation.

[0046] Free-range: River crabs: 160 crabs / kg in late January, 800 crabs / mu; 6 crabs / kg in late October.

[0047] First batch of freshwater shrimp: late January, 1000 shrimp / kg, 20kg / mu; early March, 200 shrimp / kg.

[0048] Second crop of freshwater shrimp: late July, 6000 shrimp / kg, 10-20 kg / mu; mid-to-late September, 230 shrimp / kg.

[0049] Late rice: Harvested in October–November.

[0050] Example 2 (Mode 2: Quadrivariate - Giant freshwater prawn) Engineering and equipment: Same as in Example 1 (≤10%, independent inlet and outlet, 80 mesh, push-type oxygenation ≥0.3kW / acre).

[0051] Free-range: River crabs: 160 crabs / kg in late January, 800 crabs / mu; 11 crabs / kg in mid-to-late May.

[0052] Prawns: In late January, harvest 1000 prawns / kg, 20kg / mu; in mid-to-late May, harvest 200 prawns / kg.

[0053] Giant freshwater prawns: late June, 400 prawns / kg, 8000 prawns / mu; mid-to-late September, 30 prawns / kg.

[0054] Late rice: Harvested in October–November.

[0055] Comparative Example A (rice-crab binary, other aspects are the same as in this invention) Engineering and equipment: Same as in Example 1 (≤10%, independent inlet and outlet, 80 mesh, push-type oxygenation).

[0056] Stocking: Only release river crabs (80-120 crabs / kg, 600-1000 crabs / mu in January-February); do not release freshwater prawns or giant freshwater prawns; manage late rice in the same way.

[0057] Comparative Example B (rice-shrimp single crop, other details the same as in this invention) Engineering and Equipment: Same as in Example 1.

[0058] Stocking: Only one batch of freshwater prawns is stocked (late January, 800-1200 prawns / kg, 20kg / mu), without stocking river crabs or giant freshwater prawns; the same management method is used for late rice.

[0059] Comparative example C (quaternary but lacking "low proportion, water circulation" engineering synergy) Engineering and Equipment: The area of ​​the ring ditch / pond is approximately 15%, with a water depth of 0.8-1.0m; there is no independent inlet and outlet or 80-mesh filter (water is exchanged through a shared sluice gate); microporous aeration (≥0.25kW / mu) is used instead of push-type oxygenation (which makes it difficult to form directional circulation between the ditch and the field).

[0060] Stocking: Follow the species and density of Example 1 (two crops of shrimp), and manage the late rice in the same way.

[0061] Note: Comparative examples A / B are used to demonstrate the gain of "quaternary structure and staggered double shrimp"; comparative example C is used to demonstrate the necessity of engineering-ecological synergy of "low ditch surface ratio, independent inlet and outlet, and push water circulation".

[0062] III. Main Evaluation Indicators and Measurement Methods Yield (kg / mu): Each species is measured in batches, and the total aquatic yield is calculated as a sum; rice yield is calculated based on sieved and naturally dried samples.

[0063] Survival rate (%): estimated based on the number of animals released and the number of animals caught.

[0064] FCR (Feed Rate): Feed intake / Aquatic weight gain.

[0065] Economic efficiency: Output value = ∑(unit price × output); Profit = Output value − (seedlings + feed + rice + rent + water and electricity + labor + others).

[0066] Water quality: DO, pH, temperature (surface layer of rice paddy / ditch area), ammonia nitrogen, nitrite 2-3 times per week; DO daily low value and summer ΔT (surface temperature of rice paddy area - surface temperature of ditch area) are statistically analyzed.

[0067] Frequency of drug use: Number of times chemical drugs are used (ecological management target is 0).

[0068] IV. Results and Data Table 2 Differences between Engineering and Key Management

[0069] Table 3. Output and Economic Efficiency (Mean ± SD, n=3)

[0070] Prices are calculated based on the local average price range for the same season; "—" indicates that the species was not introduced.

[0071] Table 4 Water quality and ecological stability (mean ± SD, n=3)

[0072] Statistical conclusions (overview): Using a single-factor ANOVA (n=3) comparison, Examples 1 and 2 were significantly better than Comparative Examples A / B in terms of "total output value, profit, FCR, daily low DO value, and peak ammonia nitrogen / nitrite ratio" (p<0.05); compared with Comparative Example C, Examples 1 / 2 showed significant differences in "total output value, profit, DO, ΔT, and peak ammonia nitrogen / nitrite ratio" (p<0.05), demonstrating the synergistic necessity of low channel surface ratio, independent inlet and outlet, filtration, and push water circulation.

[0073] The foregoing description of embodiments of the present invention, through which those skilled in the art are able to implement or use the present invention, will be readily apparent to those skilled in the art. Various modifications to these embodiments will be readily apparent to those skilled in the art. The general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novelty disclosed herein.

Claims

1. A method for rice-crab-shrimp quadriculture, characterized in that, The method is implemented according to the following time sequence and space configuration: S1) Construct L-shaped or back-shaped ring ditches and / or pits in the field, the total area of the ring ditches and / or pits is less than or equal to 10% of the area of the rice field, the water depth is 0.8-1.2m, the slope ratio is 1:3-1:2, the inside of the field ridge is provided with an anti-escape board, an independent drainage system is provided, and a filter screen is provided at the inlet and outlet; S2) After disinfecting the pond, water plants are arranged in the ring ditches and / or pits, so that the coverage reaches 50-60% of the area of the rice field, and a water-pushing type oxygenation device is configured to promote ditch-rice water exchange; S3) In January-February, river crab fry and blue shrimp fry are released into the ring ditches and / or pits, the river crab fry is 80-120 per kg, the density is 600-1200 per mu, the blue shrimp fry is 800-1200 per kg, and 10-20 kg per mu, the high water level is maintained, no pesticides are applied throughout the process, and the daily feeding amount is 1-3% of the body weight of the shrimps and crabs; S4) From late May to early June, machine transplanting is carried out on varieties that are resistant to fertilizer and lodging, the water level is increased after greening, no pesticides are applied throughout the process, and harvesting is completed in October-November; S5) One of the following modes is selected: Mode one: in July-August, the second batch of blue shrimps is 4000-8000 per kg, and 10-20 kg per mu; Mode two: after the river crabs and blue shrimps are caught and disinfected, in late June-early July, 300-600 Procambarus clarkii per kg, and 10-20 kg per mu are released; S7) Through water-pushing type oxygenation and water level management, the dissolved oxygen in the ring ditches and / or pits is greater than or equal to 5 mg / L, the pH is 7.5-9.0, and the feeding is carried out according to the principles of fixed time, fixed amount, fixed quality, and fixed point, and micro-ecological preparations are used; S8) Blue shrimps, Procambarus clarkii, and river crabs are caught in batches according to the growth rhythm of the species.

2. The method of claim 1, wherein Mode one: the first batch of blue shrimps is released in late January and harvested in early March; the second batch of blue shrimps is released in mid-late July and harvested in mid-late September; and the river crabs are harvested in late October; Mode two: before rice planting, the river crabs and blue shrimps are caught, the ditches and pits are disinfected by spilling quicklime, Procambarus clarkii is released in late June and harvested in mid-late September; and the river crabs are harvested in mid-late May.

3. The method of claim 1, wherein, The anti-escape board is made of plastic board, thick film or aluminum plate, is buried to a depth of 15 cm, has a height of 45-50 cm above the ground, has a circular arc transition at the corners, and has a support post every 0.8-1.0 m; And / or, the drainage system includes: the water inlet is arranged at the lower part of the anti-escape facility, and a PVC or cement pipe with a pipe diameter of 20-30 cm is used; The drainage outlet is located at the lowest point of the pond and opposite to the water inlet, a PVC or cement pipe with a pipe diameter of 20-40 cm is used, and the inlet and outlet are covered with an 80-mesh anti-escape net bag.

4. The method of claim 1, wherein, The installed power of the water-pushing type oxygenation device is configured to be greater than or equal to 0.2 kW per mu, and is turned on in high temperature or rainy and cloudy weather to enhance the ditch-rice water exchange and cooling effect.

5. The method of claim 1, wherein, The water grass is a combination of Elodea nuttallii and Hydrilla verticillata: Elodea nuttallii is transplanted in January-February, covers the ring ditch and / or pit pond, maintains the water level of 20-30 cm, adopts the plant transplanting method, and uses 50-100 kg of fresh grass per mu; Hydrilla verticillata is sown in the branch ditch in February-March, maintains the water level of 20-30 cm, and uses 5-10 kg per mu; and 50-60% coverage is maintained by cutting or replanting.

6. The method of claim 1, wherein, The water grass is disinfected with quicklime 30 days before planting, and the use amount per mu is 50-75 kg, and after the slurry is mixed, it is uniformly sprayed in the whole pond.

7. The method of claim 1, wherein, The feeding adopts a combination of complete feed and fresh fish soft particles, and the amount is 1-3% and 5-8% of the body weight of the shrimp and crab per day, and the feeding is after 16:00, and the bait is not left overnight.

8. The method of claim 1, wherein, Bird-proof facilities with a height of more than 2 m are set up, and the clearance for the harvester is considered.

9. The method of claim 1, wherein, Rice is selected from Yongyou 1540, Zhejiang 100 or Nangeng 46 rice varieties; in late May to early June, the seedlings are transplanted and grown, and the machine transplanting method is used; the row spacing of conventional rice is 30 cm x 25 cm, and the row spacing of hybrid rice is 35 cm x 30 cm.

10. A rice-crab-dual shrimp quaternary synergistic breeding system for implementing the method of any one of claims 1-9, characterized in that, It comprises: The rice field water structure composed of L-shaped or back-shaped ring ditches and / or pit ponds, the total area of the ring ditch / pit pond is ≤10% of the area of the rice field, the water depth is 0.8-1.2 m, and the slope ratio is 1:3-1:2; the anti-escape and anti-enemy device: the anti-escape plate along the ridge and the anti-bird net above the rice field; the independent drainage and anti-escape filter assembly: provided with inlet and outlet pipes and 80-mesh filter screen bags; the water-pushing type oxygenation device and its power supply circuit; the water grass habitat; the feeding site and the fixed cage fishing device; The system forms a controllable water circulation channel at the ditch-field interface, so that the ditch / pit water and the rice plant area water are directionally exchanged, so as to maintain the dissolved oxygen and temperature gradient under the condition of pesticide-free rice management, and match the cooperative growth needs of species.

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