In recent years, the market price of small crabs has been falling all the way, big crabs have gone all the way, and supply is in short supply. If you want to raise a big crab, you must have a pollution-free crab as a guarantee. The demand for pollution-free crab species has increased throughout the country. Since 2000, we have used paddy fields to cultivate pollution-free crab species and achieved good results year after year. The average price of crab species was 1.25 yuan/ton, early-maturing crabs were 20 yuan/kg, rice was 1.4 yuan/kg, and the net income per 667 square meters of crabs and rice was as high as 15,000 yuan and the economic benefits were extremely significant. The cultivation techniques of pollution-free crabs in rice fields are summarized as follows: Second, rice cultivation and management
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I. Requirements and construction of rice fields Paddy fields require a quiet environment, convenient transportation, irrigation and water conservation, soil quality is loam, and water sources are not polluted by industrial wastewater, chemical fertilizers, and pesticides. Tianjiangong consists of Weigou, Tiangou, and crab seedling holding pools, accounting for more than 25% of the total rice field area. According to the needs of symbiosis between rice and crab, a furrow with a width of 3m, a width of 1m, and a depth of 0.8m will be excavated 1.5m-2m away from the field. In the field, a crab ditch is excavated every 4m, so that the paddy field is in the form of a “fieldâ€-shaped piece, with a width of 1m and a depth of 0.6m, and it communicates with the gully. On the south side of the field, a 20m2 crab holding pool is built for every 667m2 of paddy field, and the depth is 80cm. It is used as a holding pond for intensive cultivation of large-eyed larvae or harvested crabs. The excavated earthwork was used to reinforce the field ridges, and plastic fences, No. 5 iron wires and stakes were used to build the fences and escape protection facilities on the fields. Paddy field water inlets and outlets also use mesh to prevent escape. After finishing the plots, use 7.5kg-10kg of quicklime per 667m2 of water to spray the whole field to kill the disease. At the same time, use 0.5kg of tea alum to soak in the day and night in the warm water to kill wild fish. After the toxicity disappears, plants such as black algae and water peanuts are transplanted in ponds and trenches, covering 50% to 60% of the total area.
Choose high-yielding rice varieties that are resistant to fertility, hard and unobtrusive, and resistant to disease. 15 days before transplanting, the paddy fields are planted, 500kg-750kg of fertilized farmyard fertilizer is applied per 667m2, 20kg-25kg of long-acting urea, and 35kg-40kg of superphosphate are used as base fertilizer. 2d-3d before transplanting, the seedlings were given a high-efficiency pesticide to prevent the spread and spread of rice diseases and insect pests; transplanted seedlings were required to be robust and disease-free. Usually transplanted in shallow water, wide and dense plants, row spacing 30cm-35cm, plant spacing 12cm-13cm planted. Appropriately increase the planting density in the inside of the larvae and near the crab ditch, and exert the marginal advantage to increase rice yield.
Third, the cultivation and management of crab species
Concerning the cultivation of pollution-free crabs and rice fields, good quality crabs are the key to good harvest. The production practice has proved that it is best to choose a pure Chinese mitten crab crab seedling that is robust, has a fast crawling, is neat and tidy, and has a specification of 150,000/kg. In the middle of April, the crab raising pond was disinfected with 5kg of lime every 20m2. In late April, cooked cow dung was used for 12.5kg. The appropriate feed was bred and the water was immediately injected 30cm. In early May, 0.5kg of crab seedlings were released. After the pool of crab seedlings, according to the number of natural food, supplement eggs and surimi at a ratio of 1:3 to 5, feeding 5 to 8 times a day, and the bait rate is 200%. When the crab grows to stage II, it uses minced fish, bean cake paste and bran, and feeds it in a ratio of 2:1. It is fed 3 to 5 times a day, and the bait rate is 100%. With the growth of crab seedlings. Gradually increase the amount of feeding. After 15 days, artificial feed can be fed, formula: fish meal 25%, bean cake powder 25%, vegetable cake powder 23%, wheat flour 20%, bone meal 3%, yeast powder 2%, mineral additive 2%, another 0.1% Chitin and 0.1% of complex vitamins are rolled into pelleted feeds containing 40% crude protein. Every day, every 20m2 holding tanks are fed with 3kg-5kg, which is fed in the morning and evening. Crabs were cultivated until early June, and the earthworms in the holding ponds and rice fields were dug out. Water was poured from the inlets and the crabs followed the water flow into the rice fields. One month after the arrival of the crab seedlings into the field, the daily feeding of compound feed was calculated as 20% to 25% of the crab's body weight, 1/3 in the morning at 8 o'clock, and 2/3 at 6 o'clock in the evening. From the beginning of August to the middle of September, it is the growth control stage of crabs. Usually, feeding is conducted at 6 o'clock every night. The amount of compounding material accounts for about 7% of the body weight in the first 20 days, and grass accounts for 50% of the body weight. At 3%, grass accounts for 30% of body weight. After mid-September, the growth and maintenance stage of crab species changed to plant feeds, such as raw squash and cooked hawthorn.
10% of body weight. Before the arrival of the oyster shell, increase the amount of animal feed (more than 50%), found that the crab began to shell, can be poured 3kg-5kg of lime, while the amount of water into the peanut, in order to increase the attachment of crab oyster shell; Do not change the water during the shell. Increase the number of food tables and feed them in small quantities.
For water quality management, the holding pool is filled with water every 4d-5d, each time water injection is 10cm-20cm until the water depth is 60cm-80cm. Change the water by 1/3 a day in hot weather. During the incubation period, the crabs insisted on starting daily oxygenation. After entering the field, V young crabs should try to raise the water level of the paddy field and change the water once every 3d-5d. During the summer season, change the water once a day at 10:00, changing the water volume to 1/3-1/2 of the water in the field. Raise to about 50cm, do not arbitrarily change the water level or dehydration baking field, in order to facilitate normal crab growth. In addition, the water temperature difference can not be greater than 3 °C. Every 15 days to 20 days, 667m2 of rice fields is used to sprinkling once with quicklime 5kg-7.5k batches of water to kill diseases and supplement the calcium needed for crabs.
Adhere to the inspection of the field 1 to 2 times a day to check whether there is leftover bait, water quality changes, and anti-escape facilities and whether there is predilection, etc., to determine the amount of feed, change the amount of water and take appropriate measures to prevent disease. Crab disease is mainly prevention. From July to October, a total of 500g of fibrin nets are sprayed once a day to prevent ciliate disease and black shank disease; adhere to oxytetracycline and bait to prevent bacterial diseases, the dosage is 50kg, bait Mix 1OOg, feed 3d once a month; the plants are washed before the field, and sprayed with 25s/m3 of strong chlorine spray to eradicate predators.
IV. Crab species catching and wintering
Crab species have accustomed water habits, which can be captured by running water method, that is, when the rice field is released, a sleeve net is used to trap at the drain. Or catch along the edge manually, and the remaining amount is captured after the field water is dried. The average catch rate can reach 95% or more. After the crabs are caught, they will be separated according to the size and size, and will be managed through the winter. The method is to select the river or pond with better conditions, put the crabs into crab cages or cages, submerge into the water, feed them regularly, and strengthen feed management. Strict water-proof surface will be frozen, and then in March-April the following year, people will be released into paddy fields, ponds or large water surface for crab breeding. You can also choose a crab pool with good conditions, direct wintering of crab species, strengthen winter management, make it safe for winter, and strive to eat and grow earlier in the following year. If crab species need to be sold, they are usually raised in cages or crab cages. Get up and go for the price. 