Grass-breeding fishes have a low cost of cultivation, a short cycle, and good results, and are worth promoting. However, there are still many problems in the southern part of China in the cultivation of fish, which should be properly addressed. First, the problem of fish farming in the South 1. Small area of ​​high quality forage grass for fish Although most of the fish farms have planted some grasses for fish, their planting area is small, and forage grass is not enough for fish. According to the estimation of scientific and technical personnel in Hunan Province, the current forage grasses can only meet 1/5 to 1/4 of the fish's food intake. The province has a large gap in the high-quality forage of cage fish culture. The required forage is basically from the weeds and the fish yield is relatively low. For the reservoir fish culture, the long-term lack of forage grass results in only 5 to 8 kg of fresh fish per year. Some are even lower. Freshwater fish with a marketing volume of 3/4 comes from fish culture ponds. These ponds are generally subject to the problem of shortage of green. The increase in fish production is mainly achieved by increasing the input of fine material. This method of fish farming is not only inconsistent with the main culture. The physiological needs of fingerlings increase the cost of fish farming. 2. Single species In the past 30 years, fish grown in most parts of the South have used their own species of grass, Sudangrass and ryegrass, which account for about 80% of the area of ​​grass. Together with most fisheries for many years of continuous cropping, it has reduced fertility and reduced pasture production. Ryegrass is hardy and cold, and it enters the high temperature and dry period in July. Ryegrass and most of the local weeds are yellow and cannot be cut and used. July-October is the period when the fish eats the most and grows fastest. Although there are sudangrass and bitter locust that can be used, the yield is low. Therefore, the contradiction between shortage of grass in this period is very prominent. Agricultural products have to increase the amount of concentrates such as wheat bran and glutinous rice cake. As a result, not only the cost of raising fish is increased, but also the size and quality of fresh fish are affected. 3. Grass species degradation For a long time, neglecting the work of selecting and breeding forage grasses for fish has resulted in severe degradation of grass species and decreased yield of fresh grass. According to scientific and technical personnel, Sudanese grass was planted in the 1970s, and it was cut 6 to 8 times a year, yielding 0.5 to 0.7 million kilograms of fresh grass per acre. Now, after 2 or 3 cuts, the grasshoppers will die. The annual yield per mu of fresh grass is only 0.2 to 0.3 million kilograms, and some are even lower. The available time is shortened by 50 to 60 days. 4. Severe pests and diseases of pasture Almost all Sudanese grasses have varying degrees of rust, melasma and locust occurrence. Due to the serious harm caused by pests and diseases, a variety of Sudanese grasses died and smashed. According to the Fisheries Bureau of Hunan Province, 40% to 50% of the fresh grass is inedible, and the incidence of fish is greatly increased after the fish eat this diseased forage grass. . 5. Failed to scientifically grow grass Farmers generally lack the science and technology for grass weeds. They are mainly reflected in the following: they cannot choose appropriate and suitable grass species according to local conditions; they lack scientific cultivation, management and use of new and excellent grass species; they cannot identify some poisonous and harmful weeds, resulting in fish food. Post-poisoning deaths occur from time to time; some new and excellent forage varieties and advanced cultivation techniques are being promoted slowly. Second, the improvement of the southern grass-fish farming (1) Promote good pasture The existing species of fish, such as Sudangrass and ryegrass, have been degraded, production has declined, and diseases and insect pests have increased. This has not been adapted to the needs of fishery production and development. Therefore, grass species urgently need to be replaced. The research and practice in recent years have shown that there are a number of new and excellent forages that can be widely used in the south of China. Such as the United States dwarf elephant grass, hybrid elephant grass, flat ear bull whip, hybrid Pennisetum, Emperor grass and so on. These grass species have the following common features: one-off transplantation for many years; high yield, excellent quality, high feed coefficient; strong regeneration ability, resistance to cutting; strong adaptability, wide planting area; good palatability, feeding security. (2) Combination of high and low yields The use of high-grass forage and alfalfa forage for intercropping not only increased the amount of grass production by 20% to 30% over single species of pasture, but also solved the problem of grass shortage from July to October. (3) Reasonable utilization of scientific cutting In general, the coverage of forage grasses can reach above 90% and can be cut blue. At the same time, it is forbidden to cut off the stem sections that have been rooted when cutting green. For high-grass forages, the cuttings can only be used when the plants are up to 100 cm in height. If the drought is high, the cutting should be controlled. Otherwise, it will cause death. In heavy frost areas all year round, mowing should be stopped one month before the arrival of heavy frost to protect the seedlings from winter. For the first time, the height of scorpion cutting is 3 to 4 cm. Afterwards, it is increased by 1 to 1.5 cm at a time. It is strictly forbidden to use a rusted tool to cut green when cutting green so as not to spread rust. The feeding of forage should be done with positioning, timing, qualitative and quantitative. (4) Widespread forage land to expand grass area The hydrothermal conditions in the south are good, and the potential for forage land is great. For example, there are 13,000 mu of refined fish ponds in the suburbs of Shanghai, and about 60,000 mu of ponds are available for grass cultivation. According to the survey, the use area including only one species of forage grass is less than 30%. Most of the ponds are deserted, wild grasses are breeding, and very few grasses can be harvested, and the quality is poor. Therefore, on the basis of the existing planting area, the South will make full use of the embankments of rivers, lakes, ponds, reservoirs, fish ponds, etc. and vigorously develop pasture plantations. Where conditions permit, we will strive to achieve 1 mu of surface water for 1 mu of cultivated fish, especially for cage culture. We must do our utmost to expand the area of ​​grass and strive to reach 1 mussel of fish growing into a cage with 3 mu of forage. Smoking Set,E-Cigarette Disposable,Magic Puff Disposable E Cigarette,Healcier Factory Direct Dongguan Vanilla Bioengineering Co., Ltd. , https://www.healthecigarette.de