Effect of liming and fertilization on phytoplankton distribution and primary productivity of tropical earthen ponds. – E. Ekpenyong
To investigate the effect of liming and fertilization on plankton distribution and productivity, 12 earthen fish ponds, each measuring 25mwere subjected to four different treatments, in triplicate. The treatments were no liming, no fertilization (NL/NF), liming and fertilization with cow dung (L/cow), liming and fertilization with chicken droppings (L/chick) and liming and fertilization with NPK, 15: 15: 15 (L/NPK). Phytoplankton distribution and primary productivity showed marked variation among the treatments. Phytoplankton diversity ranged from 2.38 in L/cow to 3.39 in NL/NF. The least productive pond was the control pond (0.25 mg 02m-2 hr-1) while the most productive was L/chick (0.83 mg 02 m-2-1 hr). Although nutrient loading resulted in decreased diversity, it actually enhanced significant increases in abundance of the highly nutritious diatoms and primary productivity. From the above findings, chicken droppings is recommended for fish pond fertilization considering cost effectiveness.
Keywords:Liming, fertilization, primary productivity, tropical earthen ponds.