WATER CHEMISTRY IN DIFFERENTLY FERTILIZED CARP POUNDS

Istraživan je kemizam vode u šaranskim ribnjacima - rastilištima, pojedi- načne veličine 1 ha i dubine 1,5 m, te u ulaznoj vodi u ribnjake. U ribnjacima su se uzgajali 4O -dnevni šaranski mladunci, u gustoći nasada 3-dnevnih ličinki 1,000.000 ind˙ha-1, koji su se prihranjivali trouvitom i brašnom. U ribnjacima i u ulaznoj vodi istraženi su kemijski parametri: 02, C02, CaC03-, RC03-, potrošak KMn04, N02-, N03-, NR4+, ureja, PO43-, P205 i pH (tablica 1. do 4.). Tijekom uzgojne sezone utvrđena su znatna variranja svih kemijskih parametara, ali unutar vrijednosti koje zadovoljavaju šaranske ribnjake. PHimijenjena količina mineralnih gnojiva nije uzrokovala osobito izraženu eutrofizaciju vode u obrađenim ribnjacima. Određene razlike u količini pojedinih kemijskih pokazatelja u gnojenim varijantama ribnjaka u odnosu na negnojenu varijantu nisu bile signifikantne (P>O,05), osim za vrijednost pH koja se signifikantno povećala - gnojenim varijantama (P<O,05), (tablica 6.). U usporedbi s ulaznom vodom, u svim pokusnim ribnjacima signifikantno se smanjila količina mineralnih frakcija dušika i fosfora (P<O,05), (P<O,01) i povećala vrijednost pH (P<O,05), (tablice 5 i 6).Water chemistry in carp ponds - fry carp ponds, each of them 2.5 acres big and 1.5 meter deep, as well as in inflow water in the ponds was researched. Fourty days old carp fingerlings were bread in the ponds; stock density of the three day old larvae was 1,000.000 ind˙ha-1. The fingerlings were fed with trouvit and flour. In the ponds and the inflow water the following chemical parameters were examined: : 02, C02, CaC03-, RC03-, outgoing of KMn04, N02-, N03-, NR4+, urea, PO43-, P205 and pH. During the breeding season substantial deviations of all the chemical parameters were stated, but within values that satisfy the needs of the carp ponds. The applied quantity of the mineral fertilizer did not cause a very explicit eutrophication of water in the treated ponds. Certain differences in the quantity of the respective chemical indicators in the fertilized pond variants compared to the nonfertilized variant were insignificant (P**0.05), except the pH value, which increased significantly in the fertilized variants (P<0.05). Compared with the inflow water, in all experimental ponds the quantity of the mineral nitrogen and phosphorus fractions (P<0.05), (P<O.Ol) has reduced and the pH value (P