Discussion on the technology of fully-enclosed greenhouses

In recent years, the artificial breeding of Chinese sturgeon has been developing rapidly in China. In the artificial breeding of alfalfa, people have adopted warming culture methods in winter in order to shorten the breeding cycle. The fully-enclosed greenhouse has once been favored by people for its high heat-insulating property. However, it lacks the light transmission characteristic of greenhouse greenhouses and the water quality is not easy to control. Therefore, the requirements for aquaculture technology are relatively high. Finding suitable technologies for fully-enclosed greenhouses will contribute to the further development of this farming method. From August 1997 to June 1998, the author discussed the stocking density, feed delivery, temperature control, and water exchange methods of a Chinese sturgeon breeding farm in Tianmen City in a closed greenhouse. Here are the reports:
Material method
1 Greenhouse structure
1.1 Greenhouse area The five greenhouses in the six greenhouses studied were 1,000m2 each, which was heated by a 2T boiler; the other small greenhouse area was 700m2, and was heated by a 0.5T boiler. The six greenhouses are fully enclosed reinforced concrete structures.
The cement pool in the greenhouse is set in a three-tier ladder type, with a single pond area of ​​6m2, 9m2, and 10m2. Heat pipes and heat sinks are installed in the middle and lower layers.
1.2 Water for aquaculture is underground well water, and the perennial water temperature is 18°C. Small greenhouse water is supplied by pond water, and the water temperature varies with the external environment.
2 Childish delivery
2.1 The nursery stocks raised by the juveniles are self-cultivation and self-cultivation. In 1997, the time for the seedlings to enter the greenhouse was early September, and the outdoor temperature was 23°C. In 1998, the greenhouse time was in early June and lasted for 9 months. The breeding density was divided into 15/m2, 20/m2, and 30/m2. The 15cm-thick yellow sand was placed in the pool, and a small amount of water was kept in the pool. sand. A total of 100,000 oysters are raised in the six greenhouses. After the larvae enter the greenhouse, they are bred in an outdoor holding pool. When entering the greenhouse, the quail size is 4-25 g, and the average weight is 8 g.
3 Temperature Control and Oxygenation Measures Before entering the greenhouse, warm the water in the tempering tank and greenhouse to 30°C, and keep the indoor temperature at 31°C-32°C until the whole process of greenhouse cultivation is over.
The oxygen in the greenhouse water body is a 750W inflatable aerator, two greenhouses in each building, two hours of oxygen increase every day, and oxygenation and feeding are carried out at the same time.
4 There are two ways feed can be put into feed: underwater feeding and water table feeding.
5 Water Quality Control Water quality control adopts two methods: regular flushing in the whole pond and frequent water changing in a few times.
6 Disease prevention and treatment before juvenile feeding into the greenhouse Conventional disinfection of greenhouses, water and juveniles in the greenhouse. During the breeding process, antibiotics are mixed and fed in batches. The disinfectant is sprinkled in the pool water once every half month, and the diseased clam pool is conducted. Deal alone.
result
1 Relationship between stocking density and growth rate and disease incidence Under the same conditions, the higher the stocking density is, the more significant the incidence rate is, and the lower the survival rate is (see Table 1). Juvenile clams and young clams are particularly susceptible to white spot disease and skin decay. Disease, if you do not change the water in time, the ammonia in high-density culture ponds is prone to ammonia poisoning.

Table 1 Relationship between stocking density, growth rate and survival rate
M2 delivery
(97.9.18) Harvesting
(98.6.7) Survival rate
%
Quantity
(only) Specifications
(g) Quantity
(only) average weight
(g)
1 10 300 4—20 183 320 61
2 10 300 4—20 215 356 72
3 10 300 4—20 195 372 65
4 10 200 4—20 140 350 70
5 10 200 4—20 160 370 80
6 10 200 4—20 172 346 86
7 10 150 4—20 140 456 93
8 10 150 4—20 145 475 97
9 10 150 4—20 130 423 87
There is also a close relationship between growth rate and stocking density. The higher the stocking density, the slower the growth rate.
2 Relationship between Feed Delivery Methods and Water Quality There are significant differences in the impacts of the two feeding methods on water quality. The quality of the water in the pools for underwater feeding is easily deteriorated and black, and ammonia poisoning prone to occur. Normal water quality can only last for about 3 days. The holding time of water quality in the surface water feeding is correspondingly longer, generally a small amount of water can be exchanged for 7-8 days, and the entire greenhouse can not completely change the water during the cultivation process.
3 Temperature control and water change mode The heat preservation performance of the fully enclosed greenhouse is excellent. The test is carried out at an indoor air temperature of 31°C to 34°C. The air temperature at 31°C can keep the water temperature at 30°C, while the temperature of 34°C can make the indoor water temperature. Rose to 33°C. That is, in a fully enclosed greenhouse, the temperature and water temperature differ only by 1°C.
In the two kinds of water exchange methods, the growth rate of the earthworms was faster when a small amount of water was changed, and the growth of earthworms was affected when the water in the draining pool was completely replaced.
discuss
1 The breeding method and the growth of alfalfa are not enough in the closed greenhouse, and the artificial lighting source consumes a great deal of electricity and is rarely used. As a result, the wasted feed and excreted sediment in the pond deposit the bottom of the pond; the pond water is black and the protein is decomposed. Ammonia accumulates in pool water and causes ammonia poisoning in earthworms. When greenhouses are used for greenhouse cultivation, there is solar radiation in greenhouses. The harmful substances produced by the decomposition of organic matter in culture ponds can be used by aquatic organisms, and thus they rarely appear to be toxic. phenomenon. In the two methods of sand-free and sand-bearing in the greenhouse, there is a large amount of dirt deposited in the sand culture although there is an increase in the hidden land of the earthworms. The neck erosion and epidermis blisters often appear in the breeding process. There is no hidden place for the lack of earthworms in sand farming, but it is beneficial to excrete a large amount of waste and maintain the stability of pool water when changing water. In the production process, we adopt the method of controlling the transparency of water and often changing the water in small quantities, which not only discharges part of the dirt, but also facilitates concealment.
2 The biggest difference between the temperature controlled fully-sealed greenhouse and the greenhouse greenhouse is the control of temperature. In the winter greenhouse greenhouse, the indoor temperature is required to maintain about 34°C to ensure that the water temperature of the culture pond is maintained at 301°C. In the late spring and early summer, the indoor air temperature can reach 40 °C or even 50 °C. The closed greenhouse can regulate indoor temperature of 31°C within 8 months of greenhouse cultivation and maintain indoor water temperature at 301°C, which is more conducive to the growth and energy conservation of earthworms.
3 Change the water mode thoroughly and change the water to flush out the dirt in the water completely. However, when the water is rinsed, the earthworms are irritated and bite each other, and the exchanged water is relatively transparent, so as to fight for survival space; Due to human interference, feeding in 2-3 days after changing water tends to reduce and affect growth. A small amount of water changes, each time from the bottom of the pool to discharge a small amount of water with a low temperature and rich in dirt, exchange for slightly higher temperature water, is conducive to the stability of water temperature and water quality, the impact on earthworms is minimal.
4 Feeding methods In fully enclosed greenhouses, water table feeding is adopted on the food platform to reduce feed loss in the water, save feed, maintain water quality, increase the growth rate of earthworms, and facilitate the observation of the daily feeding situation of earthworms. , Ready to adjust the amount of feed; at the same time also help to understand the growth and incidence of earthworms, timely detection and resolution of problems.



 

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