Evaluating the effect of chemical and organic fertilizers on water quality and phytoplankton growth: an experimental study

In this study, experiments highlighted the effects of chemical and organic fertilizers on water quality and phytoplankton growth using four organic treatments compared with two inorganic treatments and one mixed treatment. The use of organic and inorganic fertilizers had no unfavorable effect on the hydrological properties and profile of the freshwater used. The fertilizers, whether organic, inorganic, or mixed, positively affected the phytoplankton growth, but the best choices were treatments C (inorganic) and H (mixed) as the highest phytoplankton growth rates were recorded for these treatments. The treatment using the chemical fertilizers presented the highest phytoplankton crop, followed by the treatment using the mixed fertilizer. Total phytoplankton and Bacillariophyceae as the dominant phytoplankton groups were positively affected by nitrate, nitrite, and dissolved oxygen, whereas phosphate and temperature negatively affected them. Statistical analysis confirmed that nitrogen is the limiting factor for phytoplankton growth. The combination of organic and inorganic fertilizers gave the highest phytoplankton biomass. We conclude that applying mixed organic and inorganic fertilizers to produce abundant quantities of phytoplankton is not only necessary for fish ponds but also better and environmentally safe than using other organic manure. [GRAPHICS]