Nitrogen, phosphorus and potassium are the main nutrients in fish ponds. In the aquaculture process, the nitrogen, phosphorus and potassium in the aquaculture water are mainly supplemented by applying inorganic fertilizer and fermented farmyard manure.
Under normal conditions, the nitrogen component in ponds from June to September is not easy to lack. Because the water temperature is higher in summer, the fish eats more actively and the feeding amount increases. The excessive protein in the feed is converted into nitrogen by the metabolism of the fish, and the feces are discharged into the water. At this time, the nitrogen in the water is sufficient or even excessive.
Phosphorus is easily absent from June to September. Due to the requirement of weak alkaline water for aquaculture, weak alkaline conditions are usually achieved by splashing lime into the water. After lime is splashed into the water, the available phosphorus in the water will be combined with the calcium ions in the quick lime to produce a calcium phosphate precipitate, so that the original phosphorus can not play its due role, resulting in the lack of phosphorus in the water body. According to relevant data, the available phosphorus concentration per liter of pond water in the summer is often less than 0.01 milligrams. Phosphorus deficiency affects the growth of planktonic algae, limits its photosynthesis, and then affects dissolved oxygen in water. Therefore, phosphorus should be added to the water in time from June to September.