Winter basal fertilisers are mostly applied after clear ponds in winter. The fertilization method is to spread the well-fermented organic manure to the edge of the bottom of the pool or the water area. After a few days of exposure to the sunlight, it is turned again and then dried for several days. The water can be injected, and the base fertilizer should be applied once. The amount of fertilizer applied is based on the pond. Fatty and fertilizer types, 0.5 to 1 kg per square meter. However, fertilizer ponds and fish ponds with many years of fish farming usually do not use basal fertilizer or only a small amount of basal fertilizer.
The amount of fertilizer applied to the top dressing ponds should not be too large, especially in the summer season, to prevent the pool from decreasing in dissolved oxygen, affecting the growth and survival of fish, and keeping the transparency of the water body at 25 to 40 cm. Top dressings include manure, mixed compost, biogas slurry, biogas residue and fertilizer. Manure should be applied after fermentation in order to reduce the amount of oxygen consumed after entering the pool, but in the summer and autumn high temperature season, due to the large amount of feed, fish eat more, there are many excretions, organic decomposition is fast, the pool water is very fat, can not be topdressing manure , can apply appropriate calcium and phosphate fertilizers. Phosphate fertilizer should be selected when the sunny morning 9 to 10 pm, before the application of phosphate fertilizer should be dissolved in water, even spilled, it is best sprayed with spraying machine, fertilizing the day not flush, do not open aerator, so as not to phosphate fertilizer The bottom layer is sucked into the bottom mud.
Precautions Fertilizer should avoid the food market. For the ponds where the main grass carp, herring, or crustacean are bred, fertilization or no fertilizer should be used as little as possible to avoid over-fertilizing the water and affecting the growth of the fish. Do not fertilize on rainy days because the dissolved oxygen in the water is low. Fertilization will further reduce dissolved oxygen and accelerate fish floating. When the water temperature is low, fertilization and fertilizer and water effects are slow. If the effect of fertilizer and water is not ideal for a short time, it is necessary to wait for a period of time before making a decision. In order to reduce the loss of phosphate fertilizer, it is best to determine the pH of the water body before spraying phosphate fertilizer, and try to apply it at a pH of 6.5-7.5. Fertilization should be combined with adding water to ensure good water quality and rich dissolved oxygen.
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