Technique of raising crayfish in paddy field

The price of crayfish has skyrocketed this summer, and the midnight snack stalls on the market are in short supply. Many crayfish farmers are making a lot of money. Let's introduce the culture technology of crayfish in rice fields.

I. selection of land plots

It is advisable to choose fields with sufficient water source, convenient drainage and irrigation, good water quality and strong water retention capacity for crayfish culture, with an area of as little as a few mu, tens of mu or hundreds of mu, and a large area is better.

II. Field engineering construction

The construction of rice field with shrimp culture includes ridge reinforcement, anti-escape facilities of inlet and drain, ring ditch, field ditch, shade shed and so on. The shrimp culture ditch was excavated along the inside of the ridge of the paddy field. The width of the ditch was 1 ~ 2 m, the depth was 0.8 m ~ 1 m, and the slope ratio was 1 to 2.5. For larger fields, it is necessary to dig "field" and "well" shaped field ditches and add several small ridges in the middle of the field. The ditch in the field is 0.5-1 m wide and 0.5 m-0.6 m deep. The small ridges are used for rice management. The area of shrimp culture ditch and field ditch accounts for about 5% of the rice field area. The soil dug out from the shrimp ditch is used to strengthen and raise the ridge of the field, and the surface of the field is leveled. When the ridge is strengthened, each additional layer of soil should be compacted to prevent Rain Water from rinsing and causing the ridge to collapse.

The top of the ridge should be more than 3 meters wide and 0.5-1 meters higher. The inlet and drain should be surrounded by barbed wire or fence to prevent crayfish from escaping with the current. The water intake channel is built on the ridge of the field, and the outlet is built at the lowest part of the shrimp ditch. According to the pattern of high irrigation and low discharge, it can be irrigated and discharged. You can also hit a 1.5-meter-high pile every 3 meters away from the ridge of the field, erect it with bamboo and plant melons, beans and gourds on the ridge of the field. After the vines are on the shelf, they can play the role of shade and shelter in the summer.

III. Preparatory work before stocking

1. Trench cleaning and disinfection. From 10 to 15 days before shrimp release, 50 kg of quicklime was used in each mu of rice field, or other drugs were selected to thoroughly clear the ditch and disinfect the ditch to kill wild fish, enemy organisms and pathogenic bacteria.

2. Apply sufficient base fertilizer. 7-10 days before shrimp release, the depth of water injection in the field ditch is 50 cm ~ 80 cm, and the shrimp ditch in each mu of rice field is disinfected with quicklime of 50 kg ~ 75 kg. Then fertilize and cultivate water, generally applying 50 kg compound fertilizer, 59 kg ammonium bicarbonate or 200 kg ~ 500 kg farm organic fertilizer per mu.

3. Transplant aquatic plants. Submerged aquatic plants such as verticillium verticillata and Malay were planted in the shrimp ditch, or water spinach and water hyacinth were planted on the edge of the ditch. The area of aquatic plants accounts for 20%-25% of the shrimp ditch area, and sporadic distribution is better.

4. Filtering and escape prevention. Anti-escape and filtration facilities such as bamboo foil, barbed wire and mesh should be installed at the inlet and outlet to strictly prevent the entry of enemy creatures.

IV. Shrimp Seedling and Shrimp breeding

Crayfish seedlings should be tested in the water during stocking, and only after the water test is safe can the young shrimp be released. There are the following ways of stocking:

First, in July of the first year, parent shrimp were put directly in the rice field and allowed to reproduce on their own. According to the actual situation of the rice field, 20 kg of parent shrimp with a specification of more than 40 grams per mu was generally released, with a female-to-male ratio of 3:1. In the second year, no-tillage was used to grow rice, so that the hatched larvae could directly feed on plankton in the water of rice fields, so as to improve the hatching rate of larvae and the survival rate of young shrimp.

The second is to put in juvenile crayfish after planting rice seedlings in May, generally stocking 5000 to 8000 young shrimps with a specification of 2MUR 4 cm per mu. When stocking, soak the shrimp body with 3% salt water for about 3 minutes. While grasping the quality of shrimp seedlings, the same field must be stocked with shrimp seedlings of the same specification and fully released at one time.

V. Field management

Crayfish raised in rice fields are not required to be fed with artificial feed except for foot fertilizer. Some aquatic plants can be put into the shrimp ditch, and some animal feeds such as hammered snails, mussels and slaughterhouse feet can be fed properly during the crayfish growing season. Patrol the fields every morning and evening, and observe the changes of water color and the activity, eating and growth of shrimp in the ditch. The work of field management is mainly focused on rice water conservation, field drying, fertilization, drug use and crayfish escape prevention, damage prevention and so on.

1. Drying the fields. Rice drying field should be lightly roasted, the water level can be lowered to the surface of the field, and the time should be short, when you find that the crayfish have abnormal reaction, you should immediately inject water.

2. Fertilization in paddy field. The base fertilizer of rice field is applied into the tillage layer once before transplanting seedlings to achieve the purpose of long-term fertility. Topdressing should be applied a small number of times, a good amount is to apply half of the first half and then apply. Generally, topdressing once a month, applying urea 5 kg per mu, compound fertilizer 10 kg or fermented livestock and poultry manure 30 kg ~ 50 kg, do not apply ammonia water and ammonium bicarbonate. When applying topdressing, it is best to discharge the shallow field water first, let the shrimp concentrate in the ring ditch and field ditch, and then fertilize, so that the chemical fertilizer is rapidly deposited in the bottom field mud, and absorbed by the field mud and rice, and then deepen the field water to the normal depth.

3. Application of pesticide to rice. The principle of raising shrimp in rice fields is not to use drugs firmly, and to choose pesticides with high efficiency and low toxicity when drugs are needed, so as to avoid using insecticides containing pyrethroids. When applying the pesticide, we should pay attention to strictly grasp the safe concentration, spray the medicine on the stems and leaves of rice, try not to spray into the water, and it is best to use the medicine in different areas. To control rice borer, use 200 ml 18% insecticidal double water agent plus 75 kg water spray per mu; control rice planthopper, use 50 g 25% buprofezin wettable powder plus 25 kg water spray per mu; control rice stripe spot and rice blast. 50% carbendazim 40 grams plus water spray per mu. At the same time, add water to 20 cm in the field before spraying, and change the water in time after spraying.

4. Prevent escape and disease. Persist in patrolling the fields every day to check whether the screen of the inlet and outlet is firm, whether the escape prevention facilities are damaged, to prevent flooding in the flood season, and to prevent shrimp escape. When entering and draining water, it should be filtered with 40-80 mesh silk screen to prevent enemy organisms from entering the field. Usually to remove frogs, water snakes, Loach, Monopterus Albus, water rats and other enemy damage, so as not to harm crayfish.

VI. Feeding and management

Generally from July to September, rapeseed meal, wheat bran, land grass, melon peel, vegetables and other plant feed are fed, and more animal feed is given from October to December. The daily feeding amount is 6%-8% of shrimp body weight, one in the morning and one in the evening. 70% of the daily feed in the evening. In winter, it was fed once every 3 to 5 days, before and after sunset, and the feeding amount was 1%-2% of the body weight of shrimp. Starting from April of the following year, gradually increase the feeding amount to ensure that the crayfish are full and eat well, so as to avoid the harm of pesticide prawns.

Pipe water: in addition to drying the field, the water depth of the rice field should be kept at about 20 cm, and new water should be injected frequently. The paddy field water injection is generally carried out from 10:00 to 11:00, and the water temperature of the diversion water is kept close to that of the paddy field. When injecting water, it is necessary to drain and irrigate at the same time, so that the temperature difference is small.

At the end of June, change water 3 ~ 4 times a week; from July to August, change water 3 ~ 4 times a week, and after September, change water once every 5 ~ 10 days, and keep the transparency of shrimp ditch water 25 cm ~ 30 cm. In the field ditch, sprinkle with quicklime water every 15 ~ 20 days, each time the dosage is 5 kg ~ 10 kg per mu, in order to regulate the water quality.

If possible, an appropriate amount of Vc, Ve, and Ca can be added to the feed regularly to enhance the disease resistance and immunity of shrimp.

VII. Fishing

Crayfish cultured in rice fields are generally raised for about 2 months, and some of them can reach commercial specifications and can be caught frequently. Fishing tools include ground cage nets, shrimp cages, ecstasy and so on. The tools can be placed in the field ditch at night and shrimp can be collected the next morning.