Artificial regulation of ditch grass-prawn green culture technology

As the main species of shrimp farming in China, China’s shrimp was once brilliant in the 1980s and early 1990s, and reached the peak regardless of the scale of cultivation, yield, and foreign exchange earned through exports. However, since the shrimp disease raged in 1993, the whole culture has shrunk dramatically. Although there have been one or two alternative species after 10 years, the diseases are mostly due to disease. According to the current situation, according to the principles of ecological breeding, the author explored a green farming technique of “gourd pair shrimp” under artificially controlled conditions. It is summarized as follows: I. Ecological principles The biological environment of the shrimp pond is relatively independent, with shrimps and crabs. Such organisms are composed of the main ecological communities, and their characteristics are similar to the biological composition of the intertidal zone of the estuary and subject to artificial control. Like the natural ecosystem, it consists of three parts: producer, consumer, and disintegrator. Pond producers include plants such as phytoplankton, algae, and marine plants. They absorb sunlight, carbon dioxide, and nutrients in water to make organic matter, and aquatic life feeds and grows. Phytoplankton is the primary primary productivity in the pond, and its number and reproduction rate determine the yield and benefits of the pond. Algae are another major group of organisms in the pond. The beneficial algae include diatoms and cyanobacteria. The ditch grass is a kind of aquatic plants. Proper breeding not only does not affect the survival of shrimps and crabs, but also absorbs excess energy and inorganic salts in the water. It plays a role in purifying water quality, thereby reducing or resisting the frequent occurrence of diseases and reaching shrimp. An ideal growth state in which the species coexists harmoniously and complement each other. Second, the implementation of measures 1. The dredging of ponds was affected by diseases, and shrimp farming was gradually reduced in windfall profits. A considerable part of the shrimp farmers had adopted a triad of “putting, raising, and harvesting” in a steady state of mind and seldom invested financial resources in transforming the shrimp ponds. During aquaculture, a large amount of organic matter accumulates and precipitates, forming a layer of silt at the bottom of the pool, and some are as thick as 1 meter. This layer of sludge formed by organic matter decomposes in an anaerobic environment, and easily produces toxic components, resulting in deterioration of the water environment and causing diseases. From the perspective of the construction of most of the shrimp ponds in the Bohai Rim region, most of them are more than 50 acres per pond, and large-scale reconstruction costs are huge and shrimp farmers can hardly afford it. Therefore, it is necessary to start with ecological cultivation and carry out dredging, dipping and oxidation in the fall/winter season to solve the problem of over-thick silt and overgrown weeds. This will create good environmental conditions for shrimp farming in the coming year. 2. According to the practice of furrow weeds, the proportion of furrows in the entire pond should be less than 40%. Too much of it will affect the growth of the shrimp, and even the prawns will become entangled and die. Therefore, according to the characteristics of the strong reproductive power of the ditch grass, the scattered seeds scattered along the water, and the specific conditions of different conditions and ditch grass composition in different places, the ditch grass should be reasonably controlled. First, shrimp ponds with relatively thorough dredging are provided with convective circulation channels and feeding space. Ditch grass areas should be distributed at intervals. The second is the shrimp pond with heavy pollution and more ditch grass. Before the water is released, push the 20-30 cm pool bottom surface to the center of the pond with a bulldozer to form a rectangular ditch grass area. The four-end surface layer can be pushed to the pool nearby. The vast space for the growth of prawns in the central ditch and grass area is set aside. The following year, this method can be used to separate the central ditch and grass and form two parallel rectangle ditch grass areas. The central mode and the parallel mode can be used interchangeably. This will have the effect of facilitating construction and saving costs. (1) Planting ditch grasses For shrimp ponds with no or less growth ditch grass, ditch grass seeds should be collected in advance and planted according to a schematic pattern. The number of plants should not exceed 1/3 of the shrimp pond area. Ditch grass seed shaped like a loose pine ball, slightly smaller than peanuts, many wild species, easy to collect. (2) The spacer drug kills the ditch grass with the characteristics of diffuse growth. In order to achieve rational distribution and control, when the ditch grass grows to a height of about 3 cm in April and May, chemical drugs such as “Pucaojing” will be applied and a herbicide will be applied in the planting area of ​​Nanggou Grass in the schematic pattern. After spreading the herb for 2 to 3 days, drain the pool water to the maximum level and re-inject water to prepare shrimp. (3) Manual removal In the later period of culture, when the water quality is fertile, the ditch grass is prosperous and hinders the growth of shrimp. At this time, a manual cutting method can be used to remove or shorten the ditch; secondly, a heavy steel wire can be used to put a heavy object into the water, both sides can be hauled by the motor vehicle to the pool, and the ditch can be cut off to keep the shrimp growing. The best space. 3. The daily management is based on the conditions of shrimp ponds in various places. Generally, 0.5 to 20,000 larvae of larvae weighing more than 0.7 cm per mu are placed. In day-to-day management, the ditch grass and shrimp growth situation should be considered, and the ditch grass should be purposely increased or decreased through the methods of water intake and drainage and assisted artificial control in order to achieve the ideal breeding effect. Feed feeding, water quality observation, and patrol pond inspection are basically the same as traditional shrimp farming techniques. III. Analysis and discussion In view of the fact that no effective prevention and control measures have been developed for viral shrimp disease at present, the green farming technology of “Ditch and Grass Pairs of Shrimp” can be used to effectively alleviate the contradiction of water use during the middle and later stages of farming, and it is harmful to filter through the ditch grass and absorb water from the pool water. The ingredients play a role in degrading and purifying water, creating a good environment close to natural ecology for the growth of shrimp. Secondly, it can effectively control the incorporation of external seawater that has gradually deteriorated in the later period of cultivation, reduce the incidence of shrimp, and obtain green breeding products.