In recent years, crabs have been rapidly developed in paddy fields in Panjin City, Liaoning Province, and they have obtained good economic, social, and ecological benefits. However, traditional farming models have resulted in low yields of crab culture, small crab size, and poor quality. Under the same natural conditions, in order to explore a model of high-yield, high-efficiency, high-quality, and large-scale crab breeding, in 2002, we conducted the “Imitating Ecologically Cultured Crabs in Rice Fields†experiment in Bajianzi Town, Panshan County. Good results.
I. Selection of plots The choice of plots is in Jiangjia Village, adjacent to the canals and water sources. The area of ​​rice fields is 700 mu.
II. Field Engineering and Rice Cultivation Methods
1. The construction of the field project is to increase the water body of crabs in paddy fields, increase the water depth, regulate the water quality and resist drought, and dig 1.5m in each paddy field at a distance of 0.5m from the ground, 0.6m in depth, and 0.5m in bottom. The ring ditch is about 0.6m high and 0.5m wide.
2. The rice planting method is to increase the space and illumination of the river crab activities. The rice planting adopts two rows of large ridges, namely, 6-inch and 12-inch row spacing; 6-inch and 12-inch rows, and vacates 0.8 m at intervals of 6.0 m (20 ridges or so). Do not plant the blank space. Never use herbicides before transplanting.
Three, crab species stocking
1. Selection of crab species Selection criteria for crab species: First, to have good activities, physical fitness, not sick; Second, the specifications are neat, without injury, the appendage is complete, the surface is clean and shiny; Third, select the local culture of crab species The fourth is to directly purchase from the wintering pool of farmers, do not buy the market to collect zero sales of crab species.
2. For crab species, stocking time, and stocking rate, 120 crabs/kg, 160 ducks/kg, and 200 goats/kg were used. On April 22 and May 10, all crab species were placed Keep the pool. In the holding pool, a ring ditch was also dug. The ditch was 3.0m wide and 0.6m deep. The depth of the pool surface was 0.3m and the water depth of the ring ditch was 0.9m. The hidden pool was set in the holding pool. After 7 days of rice cultivation, the crabs in the holding pool were placed in paddy fields. The stocking capacity was 450/mu, 630/mu, 710/mu and 820/mu. In order to purify the water quality, a small amount of earthworms and earthworms have also been stocked in rice fields.
Fourth, daily management
1. Feeding the feed is the material basis for the growth of the crabs. The quality of the crabs directly affects the growth and development of the crabs and their ability to resist diseases. According to the season and the growth of the crabs, feed varieties can be adjusted at any time to meet the nutritional needs of the river crabs. From the holding pool for crabs to July, feeds are mainly based on animal feeds and crab-specific compound feeds with a protein content of 32% - 36% to promote recovery of constitution and increase the survival of clams. Rate; During the high temperature period from early July to early August, feeding compound feeds and aquatic plants with vegetable food and protein content below 20% are mainly used to keep the water quality fresh and reduce disease occurrence; after mid-August, feeding The use of high starch-containing foods, compound feeds, and animal feeds will encourage crabs to increase their fullness. The quality of the feed must be strictly controlled in the culture, and the rot or spoilage feed should not be used, and the water quality feeds should not be damaged during the high temperature season. Photosynthetic bacteria or allicin should also be regularly added to the feed.
2. Water Quality Management Crab enjoys fresh water quality. Frequent water changes can improve the water environment, increase the dissolved oxygen content in the water, and promote crab growth. Before mid-July, the water was changed every 10 days or so, each time the amount of water changed accounted for 1/3 of the total body of water. Each time when entering the water, the water quality was treated with quicklime, and the crabs were not changed in water during the shell stage. After mid-July, due to local drought and lack of water, crab ponds cannot change water. In order to maintain good water quality in crab ponds, biological agents are regularly used to regulate water quality or use some water purification drugs. After mid-August, drought conditions eased, and crab ponds changed water once every 7 days. The depth of crab-reared rice paddies was added to the highest point without affecting rice growth.
3. Once crab disease is controlled, it will inevitably affect growth and it is difficult to treat. Therefore, prevention can only be based on prevention. Liquefy is used for strict disinfection of the holding tanks with an amount of 60 kg/mu; crabs are bathed with 20 ppm of potassium permanganate for 5 minutes to 8 minutes before entering the pool; crabs are stocked and reared for 20 days after the last use of quicklime. Then, 20 ppm of quicklime was poured into the water and the whole pool was splashed with 15 ppm of photosynthetic bacteria 4 days later. Before the crabs were released 7 days later, the paddy fields prepared for the stocking of crab species were sterilized with 0.2 ppm of dibromohydantoin. Each time the water was changed, the lime was mixed with water and the whole pond was splashed with water. During the whole breeding period, lime water was splashed four times, dibromohydantoin was used three times, photosynthetic bacteria were four times, and the crab disease was effectively controlled.
V. Summary and discussion
1. A standard field project can perform normal disease prevention and drug regulation of water quality during water shortages, while large ridges and double rows preserve open spaces and provide relaxed activity space and sufficient light for normal growth of river crabs, shortening crab shells. After the restoration of constitutional time, it effectively extended the period of fattening of crabs. The crabs grow fast, have large specifications, and are not susceptible to disease under such environmental conditions. They are 1.0-fold more productive and profitable than traditional rice-raising crabs. - 1.5 times, good crabs are full-fat, reaching the pollution-free standard and selling at a higher price.
2. Field engineering and blank land account for 1/4 of the total area of ​​paddy fields, and rice yields 35kg--40kg per mu, compared with normal rice cultivation methods. Yuan - 30 yuan, but because of the use of pesticides in paddy fields to reduce the amount of fertilizer, reducing the cost of rice cultivation.
3. For rice crabs grown in paddy fields, the size of stocked crabs should be 160/kg--200/kg, and the catch rate should be 10% to 28% higher than the stock size of 120/kg, and stocking should be 400. Only - 600 are appropriate, small stocking density is conducive to the cultivation of large-size crabs.
I. Selection of plots The choice of plots is in Jiangjia Village, adjacent to the canals and water sources. The area of ​​rice fields is 700 mu.
II. Field Engineering and Rice Cultivation Methods
1. The construction of the field project is to increase the water body of crabs in paddy fields, increase the water depth, regulate the water quality and resist drought, and dig 1.5m in each paddy field at a distance of 0.5m from the ground, 0.6m in depth, and 0.5m in bottom. The ring ditch is about 0.6m high and 0.5m wide.
2. The rice planting method is to increase the space and illumination of the river crab activities. The rice planting adopts two rows of large ridges, namely, 6-inch and 12-inch row spacing; 6-inch and 12-inch rows, and vacates 0.8 m at intervals of 6.0 m (20 ridges or so). Do not plant the blank space. Never use herbicides before transplanting.
Three, crab species stocking
1. Selection of crab species Selection criteria for crab species: First, to have good activities, physical fitness, not sick; Second, the specifications are neat, without injury, the appendage is complete, the surface is clean and shiny; Third, select the local culture of crab species The fourth is to directly purchase from the wintering pool of farmers, do not buy the market to collect zero sales of crab species.
2. For crab species, stocking time, and stocking rate, 120 crabs/kg, 160 ducks/kg, and 200 goats/kg were used. On April 22 and May 10, all crab species were placed Keep the pool. In the holding pool, a ring ditch was also dug. The ditch was 3.0m wide and 0.6m deep. The depth of the pool surface was 0.3m and the water depth of the ring ditch was 0.9m. The hidden pool was set in the holding pool. After 7 days of rice cultivation, the crabs in the holding pool were placed in paddy fields. The stocking capacity was 450/mu, 630/mu, 710/mu and 820/mu. In order to purify the water quality, a small amount of earthworms and earthworms have also been stocked in rice fields.
Fourth, daily management
1. Feeding the feed is the material basis for the growth of the crabs. The quality of the crabs directly affects the growth and development of the crabs and their ability to resist diseases. According to the season and the growth of the crabs, feed varieties can be adjusted at any time to meet the nutritional needs of the river crabs. From the holding pool for crabs to July, feeds are mainly based on animal feeds and crab-specific compound feeds with a protein content of 32% - 36% to promote recovery of constitution and increase the survival of clams. Rate; During the high temperature period from early July to early August, feeding compound feeds and aquatic plants with vegetable food and protein content below 20% are mainly used to keep the water quality fresh and reduce disease occurrence; after mid-August, feeding The use of high starch-containing foods, compound feeds, and animal feeds will encourage crabs to increase their fullness. The quality of the feed must be strictly controlled in the culture, and the rot or spoilage feed should not be used, and the water quality feeds should not be damaged during the high temperature season. Photosynthetic bacteria or allicin should also be regularly added to the feed.
2. Water Quality Management Crab enjoys fresh water quality. Frequent water changes can improve the water environment, increase the dissolved oxygen content in the water, and promote crab growth. Before mid-July, the water was changed every 10 days or so, each time the amount of water changed accounted for 1/3 of the total body of water. Each time when entering the water, the water quality was treated with quicklime, and the crabs were not changed in water during the shell stage. After mid-July, due to local drought and lack of water, crab ponds cannot change water. In order to maintain good water quality in crab ponds, biological agents are regularly used to regulate water quality or use some water purification drugs. After mid-August, drought conditions eased, and crab ponds changed water once every 7 days. The depth of crab-reared rice paddies was added to the highest point without affecting rice growth.
3. Once crab disease is controlled, it will inevitably affect growth and it is difficult to treat. Therefore, prevention can only be based on prevention. Liquefy is used for strict disinfection of the holding tanks with an amount of 60 kg/mu; crabs are bathed with 20 ppm of potassium permanganate for 5 minutes to 8 minutes before entering the pool; crabs are stocked and reared for 20 days after the last use of quicklime. Then, 20 ppm of quicklime was poured into the water and the whole pool was splashed with 15 ppm of photosynthetic bacteria 4 days later. Before the crabs were released 7 days later, the paddy fields prepared for the stocking of crab species were sterilized with 0.2 ppm of dibromohydantoin. Each time the water was changed, the lime was mixed with water and the whole pond was splashed with water. During the whole breeding period, lime water was splashed four times, dibromohydantoin was used three times, photosynthetic bacteria were four times, and the crab disease was effectively controlled.
V. Summary and discussion
1. A standard field project can perform normal disease prevention and drug regulation of water quality during water shortages, while large ridges and double rows preserve open spaces and provide relaxed activity space and sufficient light for normal growth of river crabs, shortening crab shells. After the restoration of constitutional time, it effectively extended the period of fattening of crabs. The crabs grow fast, have large specifications, and are not susceptible to disease under such environmental conditions. They are 1.0-fold more productive and profitable than traditional rice-raising crabs. - 1.5 times, good crabs are full-fat, reaching the pollution-free standard and selling at a higher price.
2. Field engineering and blank land account for 1/4 of the total area of ​​paddy fields, and rice yields 35kg--40kg per mu, compared with normal rice cultivation methods. Yuan - 30 yuan, but because of the use of pesticides in paddy fields to reduce the amount of fertilizer, reducing the cost of rice cultivation.
3. For rice crabs grown in paddy fields, the size of stocked crabs should be 160/kg--200/kg, and the catch rate should be 10% to 28% higher than the stock size of 120/kg, and stocking should be 400. Only - 600 are appropriate, small stocking density is conducive to the cultivation of large-size crabs.
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