The purpose of aquaculture fertilizer is to cultivate beneficial bacteria and algae, and to be able to balance the growth and reproduction of beneficial bacteria and beneficial algae. The basic nutrients in the water are composed of carbon, nitrogen, phosphorus, potassium, etc. and their trace elements and a large amount of organic matter; while the nutrients required for beneficial bacteria and beneficial algae in the water are different, and the nutrients contained in the breeding pond determine the growth trend of algae and the growth trend of fungi. The nutrient ratio of water in aquaculture is two very important: carbon-nitrogen ratio and nitrogen-phosphorus ratio.
The carbon-nitrogen ratio required for the growth and reproduction of beneficial bacteria in water is 20 to 30:1, which means that beneficial bacteria need 20 to 30 parts of carbon if they want to decompose 1 part of nitrogen. In general, there is no shortage of nitrogen sources in water bodies, residual bait, undigested feces, dead algae and insects contain a large number of nitrogen sources, and these nitrogen sources are essential nutrients for beneficial bacteria and beneficial algae, if these nitrogen sources are too much, beneficial algae and beneficial bacteria will be left over when they are not exhausted, and in the case of insufficient dissolved oxygen, ammonia nitrogen and nitrate nitrogen will eventually become toxic and harmful ammonia nitrogen and sub-salt. The growth and reproduction of beneficial algae also requires the participation of carbon sources, and the ideal carbon-to-nitrogen ratio is 6:1. In order to achieve a balance of beneficial bacteria and beneficial algae, it is recommended that the carbon-nitrogen ratio in the water body be maintained at 15:1.
Therefore, when the ammonia nitrogen and sub-salt in the water exceed the standard, while increasing the dissolved oxygen of the water body, supplement beneficial bacteria, such as: bacillus, EM bacteria, photosynthetic bacteria, lactic acid bacteria, etc., supplement a certain amount of brown sugar, molasses and other organic carbon sources, which increases the ability of beneficial bacteria and beneficial algae to decompose nitrogen sources, thereby degrading the ammonia nitrogen and sub-salt in the water. Also in the fertilizer water, in order to promote the growth and reproduction of beneficial algae and beneficial bacteria, 5 to 7 kg of brown sugar per mu is used to supplement the organic carbon source, with the supplement of beneficial algae, to increase the probability of success of fertilizer water.
The growth and reproduction of beneficial algae is directly related to the nitrogen and phosphorus content in water, when the concentration ratio of total nitrogen to total phosphorus in water is 12:1 to 13:1, the average value is 12:1, which is conducive to algae growth, but microcystis aeruginosa grows best under the medium nitrogen-to-phosphorus ratio (N/P=4.5), and the fibrillator grows best under the low nitrogen-phosphorus ratio (N/P=0.45), so it can be found from the values that in the environment of high nitrogen and high phosphorus, the nitrogen-phosphorus ratio is low, and when the phosphorus content is too high, cyanobacteria is prone to outbreaks.
From the above data analysis, it is known that if there is a lack of phosphorus in the water body, the algae is not easy to cultivate; when the fertilizer water effect is not ideal, it is difficult to cultivate the algae, it is necessary to consider whether the phosphorus content is insufficient, and the appropriate supplementary phosphorus content can improve the fertilizer water effect and better cultivate beneficial algae.