EXPERIENCE OF THE USE OF BREWER᾽S GRAINS FOR FERTILIZFTION OF FISH PONDS

Purpose. To investigate the effect of brewer᾽s grains on formation of hydrochemical regime, development of natural forage base, and fish productivity in nursery ponds. Methodology. Generally accepted methods for hydrochemistry, hydrobiology and fish farming have been used. For general (full) chemical analysis, water samples were taken 2 times a season (at the beginning and end of the growing season), a short chemical analysis of water was conducted twice a month. Hydrobiological samples (phytoplankton, zooplankton, zoobenthos) were collected before and after the application of organic fertilizers and throughout the growing season 2-3 times a month. Findings. The article summarizes the results of studies conducted during 2007-2009 devoted to the use of different doses and schemes of application of brewer’s grains in nursery ponds. Effects of brewers’ grains of hydrochemical regime, development of natural food base (phyto-, zooplankton, zoobenthos) and fish productivity in nursery ponds have been studied. It was found that the brewer᾽s grains stimulates the development of natural forage base for juvenile fish and can be an alternative to traditional organic fertilizers ― humus. Adding of brewers’ grains (dry matter content of 29,4 %) to the nursery ponds at the rate of 2,0 t/ha (once or twice during the growing season) ensured the development of phytoplankton to 33,52 dm3, zooplankton ― up to 37,97 g/m3, benthos ― up to 3,43 g/m2. Fish productivity in nursery ponds production reached 736,3 – 754,6 kg/ha. Originality. Peculiarities of formation of hydrochemical regime and development of phyto-, zooplankton, and zoobenthos have been studied for the first time when using wastes of the brewery industry – brewer’s grains for fertilization of nursery ponds. It was found that brewer᾽s grains contribute to an increase of the development of natural forage base and fish productivity in ponds. Practical Value. Based on these results, it was proposed to put into practice the use of pond fish brewer᾽s grain, as non-traditional organic fertilizers, to stimulate the development of natural forage base nursery in ponds to enhance their fish productivity