Influence of organic manure pond fertilisation on the water quality and primary productivity of stocked ponds in Soroti district.

Abstract

The study was to determine the relationship between organic manure pond fertilization and water quality as well as primary productivity of ponds in Soroti district by analyzing and comparing the physical and chemical parameters as well as the primary productivity of the water from both organic manure fertilized and unfertilized ponds. A total of seven stocked fish ponds were sampled on which the four were fertilized using organic manures that is, pond 5, 3, 2 and Ogwetel while the three were not fertilized that is Obutei.Ogwete 2 and the Campus pond. The water quality parameters tested included temperature in degrees Celsius (oC): dissolved oxygen in mg/l, total dissolved solids in mg/l, pH and chlorophyll a concentration in mg/l, as a measure of primary productivity of the pond water, temperature, pH, total dissolved solids and dissolved oxygen were measured using a multi parameter monitor YSI model 5200A, ammonia concentration was measured using a photometer at a wave length of 640nm while chlorophyll a concentration was determined by laboratory analysis The followings readings were obtained; temperature for fertilized ponds ranged from 23 to 28.130C while for the unfertilized ponds ranged from 25.5 to 26.63oC, pH for fertilized ponds ranged from 7.3 to 8.97 while for unfertilized ponds it ranged from 7.15 to. 8.31, dissolved oxygen concentration for fertilized ponds ranged from 0.60 to 7.42mg/1 while for unfertilized ponds it ranged from 2.05 to 11.4, ammonia concentration for fertilized ponds ranged from 0 to 0.085 while for-unfertilized ponds it ranged from 0 to 0.0375; total dissolved solids levels for fertilized ponds ranged from 116.27 to 134.34mg/l while for unfertilized ponds it ranged from 110.885 to 125.07mg/l and chlorophyll a concentration for fertilized ponds ranged from 0.001 to O.007mg/l while for unfertilized ponds it ranged from 0 to O.004mg/l The results showed that organic manure fertilization has an effect of lowering the pond water temperatures and dissolved oxygen content while increasing the primary productivity of ponds. The study also revealed that organic pond fertilization has no significant effect on the pond water total solids; ammonia concentration and pH of the stocked ponds. Therefore, further research should be done to determine the effect of organic manure pond fertilization on the water quality and primary productivity of stocked ponds.