Crabs in paddy fields can remove weeds from paddy fields, reduce rice pests and diseases, and improve soils to increase rice yield. At the same time, rice provides a good environment for crab growth, development, foraging, clam shells, and habitats, reaching rice and crab lengths. In general, 350-510 kilograms of paddy rice and 25-100 kilograms of aquatic products such as fish, shrimps and crabs can be produced per acre of paddy field. The operating techniques are described below.
I. Preparation for raising crabs in paddy fields
1. The Crab Fields The crab-raising rice fields must be quiet and convenient in transportation, and they can be filled with energy, water, and fertility clay or loam. The water source is clean and free from industrial wastewater, chemical fertilizers, and pesticides. The pH is 6.8 to 9, preferably 7.5 to 8.5. Acidic rice fields can be modified with quicklime. Paddy fields should be rectangular and east-west direction, which will help increase the lighting time and facilitate management. The rice field that raises crabs is best to be contiguous and has a certain scale. Each area is between 8 and 15 acres. In order to save land, it is advisable to make reasonable use of existing waste trenches near the paddy fields, road side ditch ponds, and drainage channels.
2. Ditch ponds Excavation of paddy fields to raise crabs usually requires excavation of ring ditch, field ditch, and holding pool. The ring ditch can be excavated along the inner side of the field ridge, 2 to 3 meters away from the field ridge, 1.5 to 2 meters wide and 0.8 to 1 meter deep; the field sulcus can be widened and deepened appropriately based on the high yield groove of the rice field, showing "+", " Wells, "艹" shape; holding pool length depends on the size of the field block, generally 3 to 4 meters wide, 1.2 meters deep. The ring ditch, field ditch and holding pool should be connected to each other, and the excavated area accounts for 15% to 20% of the total area of ​​the paddy field. The excavated mud is used to raise and reinforce the stack. Tian Hao requires a height of 0.8 to 1 meter and a top width of 1 meter or more. The construction must be compacted and secured. It is best to carry out earthworks in the fall season, or to put them in good condition in the fall season, and to leave them in an empty place and choose to excavate during the winter slack season. Especially in the large-scale continuous farming of rice fields, due to the large amount of trenching and open-pit projects, it is difficult for the project to be put into operation during busy periods, and the project quality is affected. Construction in autumn and winter, after winter and spring freeze-dried weathering, piles and rakes are easily compacted, have good water retention properties, and are not prone to leakage and collapse.
3. The rice fields cultivated in the paddy fields should be separated from other farmland, and separate water channels should be built. A cement culvert with a diameter of about 40 cm should be used to directly build the influent canals, or bricks, stones, and other materials should be built into the canals. Drainage channels can use the original drainage channels in paddy fields. The inlet and outlet must be sealed with a dense wire mesh or plastic net to prevent the escape of farm animals and the entry of enemies with water.
4. Anti-escape equipment to prevent escape is the key to success or failure of rice field crabs. Crab escape prevention wall requires 50 to 60 centimeters high, 10 to 20 centimeters buried in the earth, can be prefabricated with a certain amount of cement, cement board, strong anti-oxidation capacity of calcium plastic plate, asbestos and other materials, along the rice field It is buried, supported by wood and bamboo piles, and thin iron wires are firmly clamped. The two board joints should be tight and no gaps should be left. The four corners should be curved.
Second, the four patterns of crab farming in paddy fields
1. Cultivated crabs were stocked with 80 to 120 crabs per kilogram cultivated in the previous year, and developed into large-size commercial crabs. This model requires: First, the field project construction standards to be high, injection and drainage systems, ring ditch and holding pool area accounted for about 20% of the total area of ​​paddy fields; Second, the quality of crab species is better, specifications, quantity to meet the requirements, the best It is necessary to cultivate crab breeds and commercial crab breeding facilities; Thirdly, the fence and escape prevention equipment must be solid and reliable. Generally, crabs of more than 300 kilograms of crabs produced per 15 mu can be placed with 60-75 kilograms of high-quality crabs; for crabs of 450 kilograms or more for 15 acres, 90-100 kilograms of crabs should be released; 750 kilograms of crabs should be produced for every 15 acres. Above, it should be put crab species 150 to 180 kg. The time for stocking crabs is mainly from December to March of the following year. The purchased crab species are first raised in a holding pool and intensively cultivated. After the seedlings are transplanted and live, they are then deepened and the crabs are allowed to enter the paddy fields.
2. Fast-growing large-eyed larvae (crab seedlings) with 3 crabs, which are intensively cultivated in plastic greenhouses, greenhouses, and other warming equipment, and bred for 800-2000 kg/kg of juveniles above the V level from mid-to late April. In early June, rice fields were added. This model has only 9 to 10 months of culture period from large eye larvae to commercial crabs, which has a short time, low cost, and high efficiency. The required young crabs can be cultivated by themselves, or they can be stocked directly by restocking of young crabs aged above V, which were cultivated in early-reproduction plants. Usually can be placed per kilogram 800 ~ 2000 / kg of young crabs above the V period 15 to 30 kg per 15 acres. Using this model, animal feed should be fed normally, accounting for more than 60% of the total feed, supplemented with plant foods such as cereals and aquatic plants. Careful breeding, enhanced management, and promotion of rapid growth of crabs are required. 100 grams or more of commercial crabs.
3. Cultivating Crab Species Conventional large-eyed larvae are generally stocked from early May to early June. Each 15 mu of paddy field can have 4.5 to 15 kg of high-quality macrolarvae. The purchased bigeye larvae should be surrounded by a suitable body of water in a holding pool or ring ditch, and be thoroughly sterilized thoroughly. After the toxicity has disappeared, they should be placed in rearing. The big eye larvae that were placed were fed with a paste feed made from fish eggs and eggs and fed 3 to 4 times a day. Through the fine-grained rearing management, young crabs of stage III or above are to be bred, and then the seedlings are planted and replanted. After adding water to the paddy fields, the young crabs are allowed to enter the paddy fields and grow up. Feeding baits on paddy fields to raise young baits should be properly controlled to prevent overeating and over-eating, so that the crab species are oversized and the proportion of sexual maturity is high, which affects the survival rate in the coming year. Rice field crabs, generally up to 450 to 750 kilograms per 15 acres, this is the development of crabs in paddy fields, to solve the source of crabs an important channel.
4. This polyculture model of crabs and shrimps can significantly increase the economic benefits of crab farming in rice fields. Generally, every 15 mu can be placed in 80 ~ 120 kg/kg of crab species, 37.5 ~ 45 kg, or 3000 ~ 9000 of early-bred juvenile crabs in the V period, and about 150 kg of mixed-breeding large-sized species of fish, 5 ~ 6 cm. Custoia 7.5 to 15 kilograms of shrimp, after 8 months of feeding, the end of the year can produce 15 to 450 kilograms of crabs per 15 acres, 300 kilograms of green shrimp, 750 kilograms of fish. Green prawns can be harvested on the market or purchased on the market. Before the shrimps are stocked, a certain number of plants must be transplanted in the holding ponds or in the ditch to provide breeding conditions for the egg-holding shrimps to be self-producing, self-breeding, and self-supporting.
I. Preparation for raising crabs in paddy fields
1. The Crab Fields The crab-raising rice fields must be quiet and convenient in transportation, and they can be filled with energy, water, and fertility clay or loam. The water source is clean and free from industrial wastewater, chemical fertilizers, and pesticides. The pH is 6.8 to 9, preferably 7.5 to 8.5. Acidic rice fields can be modified with quicklime. Paddy fields should be rectangular and east-west direction, which will help increase the lighting time and facilitate management. The rice field that raises crabs is best to be contiguous and has a certain scale. Each area is between 8 and 15 acres. In order to save land, it is advisable to make reasonable use of existing waste trenches near the paddy fields, road side ditch ponds, and drainage channels.
2. Ditch ponds Excavation of paddy fields to raise crabs usually requires excavation of ring ditch, field ditch, and holding pool. The ring ditch can be excavated along the inner side of the field ridge, 2 to 3 meters away from the field ridge, 1.5 to 2 meters wide and 0.8 to 1 meter deep; the field sulcus can be widened and deepened appropriately based on the high yield groove of the rice field, showing "+", " Wells, "艹" shape; holding pool length depends on the size of the field block, generally 3 to 4 meters wide, 1.2 meters deep. The ring ditch, field ditch and holding pool should be connected to each other, and the excavated area accounts for 15% to 20% of the total area of ​​the paddy field. The excavated mud is used to raise and reinforce the stack. Tian Hao requires a height of 0.8 to 1 meter and a top width of 1 meter or more. The construction must be compacted and secured. It is best to carry out earthworks in the fall season, or to put them in good condition in the fall season, and to leave them in an empty place and choose to excavate during the winter slack season. Especially in the large-scale continuous farming of rice fields, due to the large amount of trenching and open-pit projects, it is difficult for the project to be put into operation during busy periods, and the project quality is affected. Construction in autumn and winter, after winter and spring freeze-dried weathering, piles and rakes are easily compacted, have good water retention properties, and are not prone to leakage and collapse.
3. The rice fields cultivated in the paddy fields should be separated from other farmland, and separate water channels should be built. A cement culvert with a diameter of about 40 cm should be used to directly build the influent canals, or bricks, stones, and other materials should be built into the canals. Drainage channels can use the original drainage channels in paddy fields. The inlet and outlet must be sealed with a dense wire mesh or plastic net to prevent the escape of farm animals and the entry of enemies with water.
4. Anti-escape equipment to prevent escape is the key to success or failure of rice field crabs. Crab escape prevention wall requires 50 to 60 centimeters high, 10 to 20 centimeters buried in the earth, can be prefabricated with a certain amount of cement, cement board, strong anti-oxidation capacity of calcium plastic plate, asbestos and other materials, along the rice field It is buried, supported by wood and bamboo piles, and thin iron wires are firmly clamped. The two board joints should be tight and no gaps should be left. The four corners should be curved.
Second, the four patterns of crab farming in paddy fields
1. Cultivated crabs were stocked with 80 to 120 crabs per kilogram cultivated in the previous year, and developed into large-size commercial crabs. This model requires: First, the field project construction standards to be high, injection and drainage systems, ring ditch and holding pool area accounted for about 20% of the total area of ​​paddy fields; Second, the quality of crab species is better, specifications, quantity to meet the requirements, the best It is necessary to cultivate crab breeds and commercial crab breeding facilities; Thirdly, the fence and escape prevention equipment must be solid and reliable. Generally, crabs of more than 300 kilograms of crabs produced per 15 mu can be placed with 60-75 kilograms of high-quality crabs; for crabs of 450 kilograms or more for 15 acres, 90-100 kilograms of crabs should be released; 750 kilograms of crabs should be produced for every 15 acres. Above, it should be put crab species 150 to 180 kg. The time for stocking crabs is mainly from December to March of the following year. The purchased crab species are first raised in a holding pool and intensively cultivated. After the seedlings are transplanted and live, they are then deepened and the crabs are allowed to enter the paddy fields.
2. Fast-growing large-eyed larvae (crab seedlings) with 3 crabs, which are intensively cultivated in plastic greenhouses, greenhouses, and other warming equipment, and bred for 800-2000 kg/kg of juveniles above the V level from mid-to late April. In early June, rice fields were added. This model has only 9 to 10 months of culture period from large eye larvae to commercial crabs, which has a short time, low cost, and high efficiency. The required young crabs can be cultivated by themselves, or they can be stocked directly by restocking of young crabs aged above V, which were cultivated in early-reproduction plants. Usually can be placed per kilogram 800 ~ 2000 / kg of young crabs above the V period 15 to 30 kg per 15 acres. Using this model, animal feed should be fed normally, accounting for more than 60% of the total feed, supplemented with plant foods such as cereals and aquatic plants. Careful breeding, enhanced management, and promotion of rapid growth of crabs are required. 100 grams or more of commercial crabs.
3. Cultivating Crab Species Conventional large-eyed larvae are generally stocked from early May to early June. Each 15 mu of paddy field can have 4.5 to 15 kg of high-quality macrolarvae. The purchased bigeye larvae should be surrounded by a suitable body of water in a holding pool or ring ditch, and be thoroughly sterilized thoroughly. After the toxicity has disappeared, they should be placed in rearing. The big eye larvae that were placed were fed with a paste feed made from fish eggs and eggs and fed 3 to 4 times a day. Through the fine-grained rearing management, young crabs of stage III or above are to be bred, and then the seedlings are planted and replanted. After adding water to the paddy fields, the young crabs are allowed to enter the paddy fields and grow up. Feeding baits on paddy fields to raise young baits should be properly controlled to prevent overeating and over-eating, so that the crab species are oversized and the proportion of sexual maturity is high, which affects the survival rate in the coming year. Rice field crabs, generally up to 450 to 750 kilograms per 15 acres, this is the development of crabs in paddy fields, to solve the source of crabs an important channel.
4. This polyculture model of crabs and shrimps can significantly increase the economic benefits of crab farming in rice fields. Generally, every 15 mu can be placed in 80 ~ 120 kg/kg of crab species, 37.5 ~ 45 kg, or 3000 ~ 9000 of early-bred juvenile crabs in the V period, and about 150 kg of mixed-breeding large-sized species of fish, 5 ~ 6 cm. Custoia 7.5 to 15 kilograms of shrimp, after 8 months of feeding, the end of the year can produce 15 to 450 kilograms of crabs per 15 acres, 300 kilograms of green shrimp, 750 kilograms of fish. Green prawns can be harvested on the market or purchased on the market. Before the shrimps are stocked, a certain number of plants must be transplanted in the holding ponds or in the ditch to provide breeding conditions for the egg-holding shrimps to be self-producing, self-breeding, and self-supporting.
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