First, the construction of rice fields in Dianchi Lake is generally in the center of a paddy field, with a length of 10 to 30 meters, a width of 1 to 2 meters, and a depth of 0.2 to 0.25 meters, accounting for 10 to 15% of the total aquaculture area of ​​rice fields in Huanghua. First lay a layer of bagasse or corn stover (shredded) or other loosening agent at the bottom of the tank, at an amount of 2 to 3 kilograms per square meter, then coat with a layer of sludge to a total thickness of 10 to 12 centimeters, add water. Submerge the basal surface and soak it for 2 to 3 days before applying cow dung, chicken dung or swine manure, about 10 kg per square meter. A layer of sludge with a thickness of 3 to 5 cm is applied on the surface before inoculation. In addition, a layer of fermented feed (combined by 1/3 of each of bran, rice bran, corn flour, or flour) is thinly spread on the clay surface. Sprinkle 150-250 grams per square meter. Finally, add water so that the surface of the medium has a depth of 3 to 5 cm in the water layer, at which point the leeches can be introduced.
Second, the collection of species and inoculation of leeches species from the field collection. Sewage ditches and harbor wharfs in the outskirts of cities and towns, as well as wastewater pits in livestock farms and slaughterhouses, as well as waste from food factories and sewage ditch, can be collected nearby. Seed production can be harvested with a 24 mesh dense-eye polyethylene hand-gripper net, or it can be transported together with the sludge and waste residue because it contains a large amount of lice eggs. The inoculation is relatively simple, that is, the collected pods are evenly spread on the surface of the paddy field, and the introduction density is preferably 500-750 g per square meter.
Third, feeding and management 1. Feeding leeches particularly like to eat sweet and sour food feed. Livestock manure, domestic sewage, and agricultural and sideline products are also quality feeds. However, the feed (especially manure) must be fully decomposed and fermented, otherwise they will ferment in the dipper pond to produce high fever "burnt" eggs and pups. Manure can naturally decompose naturally in potholes. Food feeds are fermented with water for 16 to 20 hours before feeding. Mixing at room temperature above 20°C, add water into the dough by hand, drop it to the degree of dispersion, mix and pile up, mix well and cover with plastic cloth. If the room temperature is below 20 °C, add yeast chips for fermentation, and add about 1 piece of dry feed per 1-2 kg. Usually in the afternoon of the next day 3 to 4 seasoning, the next morning that can be matured. Unveil the plastic cloth with a rich sweet and sour scent and feed it. 2. Depth of water The depth of the central Dianchi Lake is controlled in the range of 3 to 5 cm. If the depth is too shallow, the growth of leeches will be affected. Especially in the high-temperature summer season, the pool water should be deeper, so as to reduce the light irradiation, it is better to rake in the middle of the paddy field in advance. The sky above the pool planted vine crop shading. Pool water can not be too deep, too deep will reduce the oxygen in the bottom of the water, is not conducive to the activities of aerobic microorganisms, so that the feeding of feed and fertilizer is not easy to decompose and transform. In the absence of oxygen, the otters increase the surface area of ​​the body and exacerbate the tremors in the body's tail, prompting the renewal of the water flow to increase the amount of respiration, which consumes a lot of energy and can cause severe suffocation and death. In addition, a flow rate of 0.005 to 0.01 cubic meters per second per mu of culture pond is sufficient. Mink is very sensitive to pesticides and other harmful substances in water. Industrial waste water, field water that has just been sprayed with pesticides, or medicine-containing water for the treatment of fish diseases must be kept from entering the pool.
Fourth, after the rice seedlings are stocked, they should be stocked in time. When stocking, individuals who have no disease, no injury, and basically the same size should be selected to prevent mutual food. Generally, the size of astragalus larvae that are stocked per acre of rice field is 15 to 30 centimeters, and about 0.8 to 10,000 tails per mu.
5. Astragalus membranaceus has strong reproductive ability, and hatched pups can grow eggs more than 20 days after they grow. Normal rice field Dianchi inoculation into the peak of breeding after 30 days. Astragalus ingested leeches, and took the first night to cut off water or reduce water flow, resulting in a lack of oxygen in the pool, so that the leeches were on the surface of the culture medium and they were presented with a “cockroach massâ€. At this time, the quail was allowed to feed on its own, or used 24 inches per inch. The dense mesh polyethylene net cloth is made into a hand-pick net to suck the water and feed it into the trout. When the source of bait is not sufficient, the fish can be fed with small fish, shrimp, snails, clams, oysters, fresh silkworm cocoons, chopped poultry viscera and scraps, and it is suitable for malt, bean cake, bean dregs, and bran. Can also be fed artificial compound feed, the amount of a feeding is generally 2% to 3% of the total weight of the cultivated Astragalus, other management measures are the same as the conventional methods of rearing alum. (Wang Shulin, Fishery Station, Yifeng Town, Yandu County, Jiangsu Province, China 224022)
Ecological fish farming utilizes the relationship between biological and environmental factors within the aquaculture ecosystem, as well as the relationship between biological and biological material circulation and energy conversion, and it is purposely controlled artificially to establish a new ecological balance and make natural resources effective. Use to give full play to the ecological, economic and social benefits of aquaculture. Comrade Wang Shulin has been engaged in the promotion of aquaculture technology for many years. In the long-term practice, he used the basic principles of ecological fish farming and implemented a variety of methods such as nesting, rotation, farming and fishing, and accumulated a certain amount of experience. The journal will successively publish Wang Shulin’s technologies in fish farming in the rice fields, raising oysters, breeding fish in barley, crab radish, river crab rapeseed rotation, and rotation of green prawn shrimp, for reference by fishermen and farmers. In recent years, some farmers in Yandu County have used paddy fields to cultivate and increase leeches for the cultivation of jaundice. This is a way to make full use of paddy fields for eco-fish farming, that is, by building ponds in paddy fields, introducing leeches for breeding, and feeding them on their own, plus the abundant natural foods and suitable water quality in paddy fields provide good conditions for yellow fish. The growing environment, while the yellow plover in the rice field to feed activities, dredge the field mud, prey on pests, but also created environmental conditions conducive to the growth of rice. Rice fields raise oysters, generally 30-50 kilograms of rice per mu. Using this method, in addition to doing some regular work in raising paddy fields, we must focus on the following: