First, the principle of breeding freshwater crayfish in paddy fields
The cultivation of freshwater crayfish in paddy fields is a business model that utilizes the shallow water environment of rice fields and supplemented by human intervention to grow rice and raise shrimp. The connotation of the commensal principle of freshwater crayfish breeding in paddy fields is to make up for waste, benefit each other, and harm the environment. In the practice of paddy field shrimp farming, people call it “rice farming in rice fields, shrimp farming in riceâ€.
Second, field project construction
1, the choice of rice fields
(1) Water source: The water source should be sufficient, the water quality is good, drainage and irrigation are convenient, and the irrigation and water conservancy facilities must be well-supported and have certain irrigation and drainage conditions.
(2) Soil quality: The soil should be fertile, with clay and sandy loam suitable.
(3) Area: If the area is small, then there will be more than ten acres, as many as several tens of acres, and more than one hundred acres. The area is larger than the area is better.
2. Excavation of fish ditch Excavation of circular ditch around paddy fields and larger paddy fields should also excavate the field ditch in the shape of "tian" or "chuan" or "well". The ring groove is about 3m from the field, the upper mouth of the ring groove is 4-6m wide, the lower mouth is 1m to 1.5m wide, and the depth is 1.2m to 1.5m; the field groove is 1.5m wide and 0.5-0.8m deep. The total area of ​​the ditch accounts for about 20% of the paddy field area.
3. Heightening and reinforcement The field hoe will dig the earth barrier of the excavated ring ditch on the field hoe and compact it to ensure that the ridge is as high as 1.2 to 1.5 m and width more than 3 m, and it is tightly compacted, requiring no cracking, no leakage, no failure.
4, anti-escape facilities
There are two types of anti-escape facilities commonly used. One is to install a high-density calcium plastic plate with a height of 55 cm as an anti-runner plate, buried 15 to 20 cm in the soil of the ridge, and fixed with a stake every 75 to 100 cm. Note that the four corners should be curved to prevent the lobster from climbing along the angle; the second means of escape prevention is to use mesh and hard plastic film together to prevent fleeing. In this way, the low-lying rice fields in Yijing are mainly prevented from fleeing. With a 1.2-1.5 m high dense mesh surrounding the rice field, a hard plastic film with a width of 25-30 cm can be sewn on the top of the net at a distance of 10 cm.
Inlet and drain outlets opened in paddy fields shall be protected by double-layer dense nets; at the same time, in order to prevent the dams from collapsing in the summer rainy season, an overflow port shall be provided in the paddy field, and the overflow outlet shall be filtered with a double-layer dense net.
5. Pre-reserve preparations can promptly kill predators by using rotenone, tea alum, quicklime, bleaching powder and other drugs to kill frog eggs, cockroaches, cockroaches, and other aquatic predators and parasites; planting aquatic plants to create a suitable living environment , Planting submerged plants such as agrocybe, Vallisneria, water peanuts, etc. in ring-shaped ditch and field ditch, and floating aquatic plants such as Euphorbia pulcherrima, purple duckweed, and wind eye lotus on the water surface; Water quality, in order to ensure that the lobster has ample live baits, it can be applied organic fertilizer one week before the seedlings are planted. Commonly used are dried chicken manure and pig manure, and timely adjust the water quality to ensure that the shrimp water body maintains fertilizer, living, tender and cool. The request.
Third, rice cultivation technology
1, Rice varieties Rice shrimp farms generally choose only one season of rice, rice varieties to choose a small leaf opening angle, resistant to pests and diseases, lodging resistance and strong fertility of the tight spike varieties, the current commonly used varieties have excellent series, Xie You Series etc.
2. Apply basal fertilizer 200-300 kg of farmyard fertilizer per acre, 10-15 kg of urea, spread evenly on the field surface and use a machine to plow and mix well.
3. Seedling transplanting Seedling transplanting generally starts in mid-June, and the combination of strip planting and side planting is adopted. The method of planting in shallow water is suitable for raising shrimp and paddy fields in advance. We recommend transplanting methods to use the throwing method. To make full use of the advantages of wide-row sparse planting and slopes, a transplant density of 30cml5cm is appropriate to ensure a good ventilation and ventilation performance in the lobster environment.
Fourth, lobster stocking
(1) Stocking preparation: 10 to 15 days before shrimping, clean the ring-shaped shrimp ditch and field ditch to remove floating soil, correct the collapsed ditch, and use 20 to 50 kg of quick lime for the ring-shaped shrimp ditch per acre of paddy field, or use other drugs for ring Shrimp trenches and field trenches are thoroughly cleared by gutters to kill wild fish, predators and pathogens. 7 to 10 days before stocking, paddy fields are filled with 30 to 50 cm of water, and 800 to 1 000 kg of livestock manure is applied per acre in the ditch to fertilize the water. At the same time, transplant submerged plants such as Hydrilla verticillata and Malay Oozi, etc., to require l/2 of the ditch area, thereby creating a good ecological environment for the stocked lobsters.
(2) Transplanting Aquatic Plants: Aquatic aquatic plants such as Hydrilla verticillata, Ceratophyllum deliciosus, and Malay Oozi are planted in the ring-shaped shrimp gully. Grown vegetables are planted on the sides of the gully, and water hyacinths are planted on the water surface. However, in order to control the area of ​​aquatic weeds, aquatic plants generally account for 40% to 50% of the area of ​​the ring-shaped shrimp ditch, and they are better distributed in a sporadic manner. Do not gather together, which is conducive to smooth and unobstructed water flow in the shrimp ditch.
(3) Restocking time: Whether it is the shrimp species in the current year or the broodstock holding eggs, we must strive for an “early†character. Early release can not only extend the growth period of shrimp in paddy fields, but also make full use of the large amount of natural feed resources cultivated in rice fields after fertilization. Regular stocking time is generally at the end of August to September or the end of March of the coming year, and can also be taken at any time for stocking at any time.
(4) Stocking Density: 20 to 25 kg per mus of paddy field broodstock stocking, ratio of male to female 3:1. Caterpillar larvae can also be stocked in March of next year, and they will be placed at 0.8 million to 10,000 per acre of paddy fields. Note that brooding broodstock should be kept in the outer furrows for overwintering. When the pods return to green, they will be induced into the paddy fields. After June, they will be added at any time. The juvenile shrimps that were artificially reared in the same year are mainly used.
(5) Dredging operations: In the paddy field stocking of shrimp, generally choose sunny morning and evening or rainy days, when the weather is cool, the water temperature is stable, which is conducive to the lobster for stocking to adapt to the new environment. When stocking, put more points around the ditch, so that the lobster seed in the ditch evenly distributed, to avoid excessive concentration, resulting in hypoxia suffocating dead shrimp. When freshwater crayfish are stocked, they should pay attention to the quality of juvenile shrimp. The stocking specifications of the same field should be as tidy as possible, and should be sufficient once for stocking.
In addition, it is recommended to open earth ponds in Tiantou for temporary raising. The specific method is to excavate a 2% to 5% earthen pond in the paddy fields for the first half of the month before the broodstock is stocked. This is used to raise broodstock. Until seedlings transplanted for one week and the seedlings survived and returned to green. The holding tank and earthen pond can be dug through and stimulated by micro-flowing water to promote the growth of broodstock into the field. This method is commonly referred to as secondary shrimp farming in rice fields. Using this method can effectively improve the survival rate of lobsters, and it can also promote the lobsters to adapt to the new ecological environment.
Fifth, water level adjustment
Water level adjustment should be dominated by rice. In the initial stage of larva rearing, the water should be shallow and be maintained at about 10 cm. However, due to the continuous growth of shrimp and the heading, flowering, and grouting of rice, a large amount of water is needed, so the field water can be gradually deepened. To 20-25 cm, to ensure the water requirement of both (shrimp and rice). Shallow irrigation is adopted during the effective tilling period of rice to ensure normal rice growth. When the rice enters the invalid tillering stage, the water depth can be adjusted to 20 cm, which not only increases the activity space of lobster but also promotes the increase of rice yield. At the same time, attention must be paid to observe the water quality of the ridge. Change, generally every 3 to 5 days to add new water; summer season, every 1 to 2 days to add a new water, in order to keep the field clean.
Six, feeding management
First of all, through the application of basal fertilizer, timely fertilizer, cultivation of a large number of Cladocera, copepods and benthic organisms, while in March should also stock some snails, 150-250kg per mu of rice fields, and transplant enough plants to grow lobster Development provides a rich natural feed. In the feeding of artificial feed, under normal circumstances, according to 40% of animal feed, 60% of plant feed ratio. When feeding, timing, positioning, quantitative, and qualitative feeding principles should also be implemented. In the early morning, they are fed once every afternoon and once in the afternoon; they are fed once more in the late afternoon at 6 o'clock in the evening. The types of feeds for feeding were mostly small fish, snail meat, river meat, quail, animal viscera, silkworm cocoons, and were fed with corn, wheat, and barley flour. Can also be fed a proper amount of vegetable feed, such as water hyacinth, leeches, duckweed and so on. The daily feeding amount of shrimp is 3% to 5% of the shrimp body weight. We must insist on checking the eating conditions of shrimps on a daily basis. The foods fed on that day are eaten within 2 to 3 hours. This indicates that the amount of feed is insufficient, and the amount of feed should be increased appropriately. If there is surplus on the second day, then the feeding is The amount should be reduced appropriately.
Seven, scientific fertilization
Shrimp farming rice fields are generally dominated by base fertilizers and decomposed farmyard manures, which promotes stable growth of rice, maintains medium-term non-disruptive force, and does not cause premature senescence in the later stages. The population is easy to control, and 300 kg of farmyard manure, 20 kg of urea, and 20 μg superphosphate can be applied per acre. 25 kg, potassium sulfate 5 kg. Generally no top dressing is applied after shrimp is put in order to avoid reducing the dissolved oxygen in the water in the field and affecting the normal growth of the lobster. If de-fertilization is found, a small amount of topdressing urea may be used, no more than 5 kg per mu. The method of fertilizing is: firstly row shallow field water, let the shrimp concentrate in the fish ditch and fertilize, help the fertilizer to be quickly deposited in the sediment and be absorbed by the field mud and seedlings, and then deepen the field water to normal depth; a small amount can also be taken. Repeatedly spreading the fertilizer or fertilizing the roots. Chemical fertilizers that are harmful to freshwater crayfish, such as ammonia and ammonium bicarbonate, are prohibited.
Eight, science application
Rice field shrimp can effectively inhibit the growth of weeds, lobsters feed on insects, and reduce pests and diseases. Therefore, the use of herbicides and pesticides should be minimized. After the lobsters enter the field, they can be removed manually if grass shortages occur again. If there is a serious need for drug use due to paddy field disease or shrimp disease, the following key points should be mastered: 1 Scientific diagnosis and proper remedy; 2 Selection of high-efficiency, low-toxic, low-residue pesticides; 3 As lobster is a crustacean, it is also a bloodless animal. Phosphine drugs, pyrethroids, and pyrethroids are particularly sensitive, so use drugs such as trichlorfon and methamidophos with caution. Do not use drugs such as the enemy to kill them. 4 When spraying pesticides, you should generally deepen field water to reduce drug concentration. , To reduce the harm of drugs, you can also dry up the field water and re-use the drug, and immediately after 8 hours to the normal water level; 5 powder drugs should be sprayed in the morning when the dew does not dry, water and emulsion drugs should be sprayed in the afternoon; 6 precipitation The speed should be slow, and then shrimp should be applied after the shrimp climbs into the fish ditch; 7 can be divided into batches of medication, that is, first half of the paddy field, and then the other half after 2 days, while trying to avoid pesticides directly fall into the water, Ensure the safety of lobster.
Nine, scientific field
The principle of drying up the field is: "Usually when water is along the embankment, the water level of the drying field is low, the gutters will slip and the sun will not hurt the shrimp." Before drying in the fields, it is necessary to clean the fish ditch and prevent it from blocking and silting. The general requirement of the drying field is light sun or short-term drying. When drying in the field, the water depth in the ditch is kept at 13-17 cm, so that the middle of the field does not sink into the foot, and the tops of the fields are not cracked and whitish to see the floating roots of rice. Moderate. After drying the field, restore the original water level in time. Try not to burn too long as much as possible to prevent the shrimp from eating too much and affecting growth.
X. Disease prevention
Diseases of lobster adopt "prevention-based" scientific prevention measures. Common predators include water snakes, mice, jaundice, muddy birds, and birds. Efforts should be taken to expel or indulge them. In the early stage of shrimp release, the rice plant had no flourishing stems and leaves, and there was a large gap in the field surface. At this time, the individual shrimp was also small and had a weak activity ability. The capability of escaping from predators was poor and could easily be attacked by predators. At the same time, freshwater crayfish need to be clam shell once every time to grow, and in the clam shell or just clam shell, it is most likely to become a predilection bait. By the time of harvest, due to the shallowness of the field, the shrimp may crawl everywhere, the target will be larger, and it will also be easily eaten by birds and beasts. In this regard, it is necessary to strengthen the management of the field and to prevent enemy enemies in a timely manner. If necessary, some color strips or scarecrows can be set up in the fields to threaten and drive waterbirds. In addition, when the shrimp is stocked, it is also forbidden to feed the ducks down the trench and avoid losses.
Eleventh, strengthen other management
Other day-to-day management work must be done on field inspections, diligent inspections, diligent studies, and diligent records. We insist on inspecting the fields sooner or later, checking the activities of shrimps, ingesting water quality, deciding on feeding, and fertilizing quantities. Check whether the dike is leaking, and whether the water shortage or the barbed shrimp facilities are firm and prevent the escape of shrimp and enemy enemies. Check the fish ditch, fish nests, clean up in time to prevent clogging. Check the water quality of the water source and prevent harmful sewage from entering the rice fields. It is necessary to analyze the existing problems in a timely manner and do a good job of recording field files.
Twelve, harvest
Rice harvesting generally adopts the method of collecting stubble in the valley, and then raises the water level to 40-50cm, and fertilizes properly to promote the greening of the rice piles, providing shade-free places for lobsters and natural feed sources. The fishing time for shrimps in rice paddies ranges from 4-9. Months are acceptable, mainly using cage traps.
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