Technical points of mixed culture of Zizania caduciflora and crayfish

With the continuous improvement of people's culture level and the continuous innovation of culture technology, many new culture models have emerged. mixed culture is not only a more popular, but also a relatively new culture model. Mixed culture can not only benefit from culture, but also effectively reduce the culture cost by using more than one pond.

Technical points of mixed culture of Zizania caduciflora and crayfish

1. The ponds with sufficient water source, no pollution, convenient sewage discharge, strong water retention, deep plough layer, middle and high fertility and an area of more than 1 mu can be used to grow Zizania caduciflora and raise shrimp.

Second, shrimp pits are built around the ridges to dig circular shrimp pits with a width of 1.5-2.0 meters and a depth of 0.5-0.8 meters, and appropriate middle trenches are dug in the middle of the larger pond, with a width of 0.5-1 meter and a depth of 0.5 meters. The total area accounts for 8% of the pond area, and the maximum area of each shrimp pit is no more than 200 square meters. Before releasing freshwater crayfish, install fence facilities into the pond outlet. Third, anti-escape facilities are simple, with hard plastic film buried in the soil 20 cm, soil exposed 50 cm can be. The outside of the plastic film is fixed with bamboo or wooden piles every 1 meter or so. 4. Fertilizing the base fertilizer before planting Zizania caduciflora from February to March every year, it can use mature pig, cow manure and green manure 1500 kg / mu, calcium magnesium phosphate fertilizer 20 kg / mu, compound fertilizer 30 kg / mu. Turn into the soil layer, rake flat rake fine, fertilizer mud integration, you can transplant Zizania caduciflora seedlings.

Fifth, the seedlings of Zizania caduciflora were selected from mid-September to early October, and the high-quality plants with strong plant, medium height, flat stem and high purity were selected as the remaining seed. 6. timely transplanting Zizania caduciflora from late March to mid-April, split it into several small piers with a sharp blade along the tiller, with 4-6 stolons and robust tiller buds per pier, cut off leaves, retain the leaf sheath length of 16 cm-26 cm, reduce evaporation, in order to survive early, dig, divide and plant. The row spacing of plants is determined according to the planting period, the number of seedlings divided into piers and the times of harvest. Zizania latifolia is planted in large and small rows with large row spacing of 1 meter, small row spacing of 80 cm, hole spacing of 50 cm-65 cm, 1000-1200 holes per mu, and 6-7 seedlings per hole. The planting method is 45 degrees oblique planting, and the depth is buried at the base of the rhizome and tillers, while the tiller buds are slightly exposed to the water. 7. The freshwater crayfish were disinfected in the shrimp pit 10 days before the transplanting of Zizania latifolia seedlings. The newly built shrimp pits must first be soaked in clean water for 7-10 days, and then continue to soak in fresh water for 7 days before releasing shrimp. 5000-10, 000 crayfish of 2 cm-3 cm per mu can be released. The young shrimp should be placed in shallow water and water hyacinth floating planting area. When the shrimp species are put in, the shrimp species should be soaked in salt water for 5 minutes to prevent the occurrence of shrimp disease. At the same time, 20 kg-30 kg snail per mu and 1.0 kg-2.5 kg per mu.

Scientific management 1. Water quality management: take "shallow-deep-shallow" (planting in shallow water, living trees in deep water, shallow water tillering) as the principle. Irrigation 30 cm before sprouting, keep water depth 50 cm-80 cm after planting, shallow water 80 cm before tillering, promote tillering and rooting; to late tillering, water deepens to 100 cm-120 cm, control ineffective tiller. During the high temperature period from July to August, it is appropriate to maintain a water depth of 130 cm-150 cm. 2. Scientific feeding: feed concentrate according to the season, such as vegetable cake, bean dregs, wheat bran, rice bran, earthworms, fly maggots, fish pellets and other aquatic animals. It can be fed with self-made mixed feed or special feed for fish, or some animal feed, such as snail clam meat, fish, earthworms or harvested Cladocera, copepod, leftovers from animal slaughtering plant, etc. feed at a fixed point along the shallow water around the edge of the pond. The amount of feeding is generally 5% of the body weight of fish and shrimp, 10% of the body weight, adopting the "four fixed" feeding method, and feeding in the evening accounts for 70% of the whole day. Feed twice a day, from 8am to 9am and from 18:00 to 19:00 in the evening. 3. Scientific fertilization: basic fertilizer is commonly used in human and animal manure and green manure. Topdressing multi-use chemical fertilizer, should be a small number of times, can choose urea, compound fertilizer, potash fertilizer, etc., forbid ammonium bicarbonate. Organic fertilizer should account for 70% of the total fertilizer. 4. Medication of Zizania caduciflora: pesticides with high efficiency, low toxicity, low residue and no effect on mixed lobster were selected. Change fresh water immediately after application, and it is strictly forbidden to spray at high temperature at noon. 9. According to the harvest season, Zizania caduciflora can be divided into one mature Zizania latifolia and two mature Zizania latifolia. After harvesting Zizania caduciflora, the mud in the pier should be cultivated on the stem of the plant by hand. Generally, the yield of Zizania caduciflora is 750kg-1000 kg per mu. Lobster harvest can use cages, shrimp cages to catch crayfish. It usually produces 200 kilograms of crayfish per mu.

The living habits of crayfish

Crayfish are nocturnal animals that live in benthic and crawling camps. Inhabit lakes, rivers, reservoirs, swamps, ponds and ditches, and sometimes in rice fields. However, there are more food-rich still water ditches, ponds and shallow lakes, the habitat is mostly soil, there are more hidden things such as water plants, tree roots or stones. During the day, they often lurk in dim corners, rocks, grass or caves at the bottom of the water body, and come out to feed at night.

Under natural conditions, foraging is also seen during the day because of lack of bait and low transparency of the water body. The shrimp has strong climbing ability and digging ability. In the case of anoxia, lack of bait, pollution and other biological, physical and chemical factors, they often climb out of the water and enter another body of water. If it rains, especially when it rains heavily, the shrimp often climbs out of the water and moves outside the body. During the growing period, crayfish hardly dig holes. The longest crayfish cave can reach 100cm and its diameter can reach 9.2cm. Crayfish can make use of the original caves and other hidden objects in artificial caves and water bodies, and their burrowing behavior often occurs in the breeding season. Therefore, the proper addition of artificial nests in the culture pond and technical measures can greatly reduce the damage of the shrimp to the pond ridge and embankment.

Crayfish are widely distributed in all kinds of water bodies, especially in still water ditches, shallow lakes and ponds. The results showed that the shrimp had strong adaptability to eutrophication and hypoxia. If the dissolved oxygen in general water is kept above 3mg/L, it can meet the needs of its growth. The shrimp can survive more than a week if it leaves the water.

Crayfish have strong adaptability to high or low water temperature. This is consistent with its distribution across tropical, subtropical and temperate zones. The suitable temperature range is 0 ℃ ~ 37 ℃. In the Yangtze River basin, the crayfish can survive when it is frozen outside at night, but the optimum temperature range for crayfish is 18 ℃ ~ 31 ℃.

What problems should be paid attention to in raising lobster?

1. Seedling: there is no "hybrid variety" of lobster. At present, natural seedlings are abundant and cheap, but artificial seedlings are still in the laboratory stage. In addition, do not mistakenly believe that lobster species are bought at a high price from other places after domestication and killing each other less. There are also many people think that as long as they put into planting lobsters in the first year, they can get good profits every year through their own continuous reproduction. in fact, the yield of lobster culture is the highest in the first year, and then decreases year by year. Because the life cycle of lobster is 16-18 months, coupled with inbreeding, functional degradation, disease resistance decline, the yield will drop sharply or even no harvest after 3 years.

2. Water quality: some people think that lobsters can also grow well in smelly ditches, but not both good and bad water can be raised. Fresh water quality is the key to the high yield of lobster culture. It is required that the coverage of aquatic plants in the pond should be 30-60%. The transparency of the water body is about 30 cm, the dissolved oxygen content is more than 5 mg / L, the water should be changed regularly, and the water level is kept above 80 cm in the high temperature season.

3. Feed: lobster is an omnivorous animal bait creature, and its growth depends on the intake of protein. It can be mainly composed of fresh miscellaneous fish and field snails, supplemented with plant food, or a compound feed with a protein content of no less than 32%. Rotten animal and plant feed should not be fed because of its low utilization rate and easy to deteriorate the water quality.

4. Disease: some people think that "lobster will not get sick". In fact, it is not. After high-density culture, various environmental factors are easy to cause lobster disease. The solution is mainly prevention and regular use of drugs. In the process of culture, the water body should be disinfected regularly. If the pH value of the water is less than 7, quicklime should be pulped at a concentration of 20 grams per cubic meter and sprinkled evenly every 15 to 20 days. In general, the pond was disinfected with chloride every 15 to 20 days, and molting growth-promoting hormone was added to the feed every half a month for 3 days.

5. Mixed culture: many people think that lobster can be mixed with fish in order to make rational use of space and improve the efficiency of aquaculture. In fact, lobster must not be mixed with carnivorous or omnivorous aquatic products. Because the lobster is most likely to be eaten when it is shelled, and silver carp and bighead carp are its natural enemies when the lobster is born, so mixed culture is not recommended.

Construction of lobster culture site

1. Culture environment

Lobster culture sites should choose places with sunny ventilation, quiet environment, sufficient water sources without pollution, rich sources of bait, convenient drainage and irrigation, convenient transportation and power supply, and can use water from rivers, lakes, reservoirs and ponds as water sources. Well water and spring water can also be used, and the PH value of water quality is about 6: 8.

2. Shrimp pond environment

Lobster culture pond area can be large, small, water depth of 0.6-1.5 meters, the best east-west direction, toward the sun, the pool around a slight slope, flat bottom, slightly inclined to the side of the drain, easy to drain the pool water. The pond must be surrounded by soil slope protection, mainly lobster hole habitat, so that it can survive the winter safely. The ridge is 40cm high and 50cm above the water surface, and the width of the ridge should reach 1m, mainly to prevent lobster from drilling holes and filtering water. if the pond area is more than 10 mu, one or two additional ridges can be built in the pond, which are evenly distributed in fields, wells and crosses, mainly allowing lobsters to drill holes and spawn and reproduce. Lobsters like nocturnal activities and crawl along the ground. Asbestos tiles and plastic films should be used on the periphery of the pool ridges, and wooden piles should be used as supports to build an anti-escape wall with a height of 50 centimeters. the bottom is buried in about 30 centimeters sealed to ensure that no lobsters can escape.

3. Disinfect the pool

The common disinfection method of lobster pond is to use quicklime to disinfect. During disinfection, only 5 centimeters of stagnant water is left in the pool water, and quicklime is evenly sprinkled into water slurry to dissolve. The dosage of quicklime is generally 25 kilograms per mu. On the second day of using quicklime, the bottom of the pool is stirred with iron rakes to fully mix lime slurry and silt. Do not release the disinfected water, stay in the pool, start to enter the water the next day, and reach the required level of feeding. At the same time, the lobster will molt in the process of growth, must take in enough calcium, the calcium content of quicklime is more than 50% (the theoretical value is 71.4%), and the effect is better when the price is low.

Although mixed culture is a relatively good breeding model now, it still has a lot to pay attention to. After all, two different things are raised together, and they all have their own needs and growth environment. It is necessary to achieve both independent growth and peaceful coexistence between the two in order to create greater profits.