Water management: Water management is an important link in the process of fish farming in rice fields. Rice should be the main crop. Within 20 days after transplanting, the water depth is 3.5 cm, allowing the rice to tiller in shallow water. At this time, due to the short stocking time and small individuals, the requirements for water level are not too high. After 20 days, the tillering of seedlings basically ended and the fish gradually grew up. At this time, the water in the field can be as deep as 5 ~ 7 cm, and it can be as deep as 10 cm with the growth of seedlings, which is beneficial to control the ineffective tillering of seedlings and the growth of fish. It is necessary to control the water level in late rice fields. Because the temperature is high when transplanting late rice, it is necessary to deepen the field water to prevent the seedlings from dying, which is good for both fish and rice.
Changing fields: Changing fields for fish farming with double cropping rice is also an important part of fish farming in rice fields. During the period from early rice harvesting to late rice transplanting, there is farm work to be done, which often causes some fish to die. In order to avoid this kind of loss, we must do a good job of changing the field.
The role of fish ditch and fish slide should be brought into play in the field changing work. It is to slowly release water before harvesting early rice and let the fish swim into the fish tank along the fish ditch. Or cut rice with water, then concentrate the fish in the fish tank through the fish ditch, temporarily raise the periphery of the fish tank with soil, and introduce fresh water to make the fish tank become a temporary pool, and then put the fish into the whole field after plowing and harrowing the field; Then transplant rice late, sometimes leading to the death of some fish. Fish are transferred from early rice fields to small ponds for temporary cultivation by fish ditches and fish slides, and the late seedlings are transplanted and put into rice fields. This method rarely kills fish.
Fertilization: It is advisable to apply basic fertilizer and decomposed farmyard manure to fish-farming fields, which can promote the stable growth of rice, keep vigorous in the middle period, prevent premature aging in the later period, and make the population easy to control. There are no special requirements for the application of base fertilizer and farmyard manure in fish farming paddy fields. If urea and ammonium bicarbonate are used as topdressing, the safety of fish must be ensured. The available nitrogen fertilizers are urea, ammonium sulfate and ammonium nitrate. Phosphate fertilizer has calcium superphosphate, potassium fertilizer has potassium chloride and so on. Ammonia water should not be used as base fertilizer, not to mention topdressing, and ammonium bicarbonate should be used as base fertilizer, both of which are corrosive and stimulate fish. Fertilization should be based on the principle of small amount and multiple times, and half a field should be applied at one time. First, the field water should be filled up along the embankment, and be careful not to sprinkle chemical fertilizer directly in the fish ditch and fish tank. According to our experience, the application amount of urea per mu should not exceed 8kg, ammonium sulfate should not exceed10kg, ammonium bicarbonate should not exceed 4kg and ammonium chloride should not exceed 3kg.
Application: Application in paddy field will not affect fish as long as it is handled properly. To prevent and control rice diseases and insect pests, it is necessary to choose high-efficiency and low-toxicity pesticides, master appropriate concentrations and correct application methods, and prohibit the use of mercury preparations and herbicides. In order to ensure the safety of fish, water with a depth of 4 ~ 8 cm should be added in advance when applying various pesticides to control pests and diseases in fish farming rice fields. Different application methods should be adopted according to the different characteristics of drugs. At the same time, when spraying liquid medicine (powder), it should be noted that the powder should be sprayed with dew in the morning, and the nozzle should be raised so that the medicine can be sprayed on the leaves of rice and grass as much as possible to prevent the powder from directly spraying into the water body of rice field. When the dew is dry on a sunny day, spray water, with the nozzle facing up. If fish poisoning is found after application, fresh water must be added immediately to dilute the drug concentration in the water. Don't apply pesticides before it rains or thunders, otherwise the drugs will fall into the fields by the rain, and in severe cases, fish will die.
Dry land: the water demand of rice is constantly changing during its growth and development, and the water demand of fish farming and rice is the main contradiction. The large amount of water in the field and the long time to keep the water layer are beneficial to the growth of fish and unfavorable to the growth of rice. Agricultural proverbs scientifically sum up the water consumption of rice, that is, "planting seedlings in shallow water, living trees in deep water, tillering in shallow water, dehydrating dry land, rehydrating and growing thick, heading in big water, wet filling, and alternating dry and wet." Therefore, experienced old farmers often use dry land to suppress ineffective tillering, and at this time, the water level is very shallow, which is very unfavorable for raising culter ilishaeformis. Therefore, it is very necessary to control the water level in rice fields. In production practice, we summed up an experience, that is, "the water level in the field is low at ordinary times, and the ditch works, so the fish will not be hurt in the field." Before drying the field, clean the fish ditch to prevent it from blocking and silting up. Field drying generally requires mild or short-term drying. When airing in the field, the water depth in the ditch should be kept at 13 ~ 17 cm, so that the middle of the field does not sink and the topsoil at the edge of the field does not crack and turn white. It is appropriate to see the floating roots of rice turn white. After drying the field, restore the original water level in time. Try not to bask in the sun for too long, so as not to affect the growth of fish because there is no food for too long (figure 16).
Figure 16 Schematic diagram of the relationship between water level, water temperature and field drying in paddy field
Feeding: Generally speaking, raising culter ilishaeformis in rice fields does not need more feeding. If the paddy field is too thin and there are too few live baits in the water, especially when the animal baits are not enough to meet the growth and development of the culter ilishaeformis, it is necessary to put other live baits such as loach and wheat ear fish, or put the prepared compound feed regularly and regularly.
Daily management: other daily management work must be diligent in field inspection, inspection, investigation and recording. Adhere to patrol the fields in the morning and evening, check the activities of fish, eat water quality, and decide the amount of feeding and fertilization. Check whether the dike body is leaking, whether the level water is short, and whether the fish fence is firm, so as to prevent fish and enemies from entering. Check fish ditch and fish nest, and clean them in time to prevent blockage. Check the water quality of the source water to prevent harmful sewage from entering the rice field and prevent fish from floating head due to lack of oxygen. It is necessary to analyze the existing problems in time and make on-site file records.