Chemical speciation of sedimentary nitrogen and phosphorous in integrated fish/pig farming system

Abstract

Experiments were carried out to investigate the temporal variations of different chemical species of sedimentary nitrogen
and phosphorus in fish/pig integrated farming system particularly in a hardwater seasonal pond. In sediments, exchangeable
ammonia contributed to an average of 14.87 and 16.10 % of total exchangeable inorganic nitrogen in treatment and control
pond respectively. Highest percentage contribution of exchangeable nitrate (average contribution above 77.05%) to total
exchangeable inorganic nitrogen could be recorded in these ponds. Availability of exchangeable nitrate in the sediments of
these ponds confirmed the total absence of denitrification. The percentage contribution of different speciation of phosphorus
such as exchangeable phosphorus (E-P), apatite phosphorus (A-P), phosphorus bound to organic matter
(O-P) and phosphorus bound to oxides of iron and manganese (O-Fe-Mn-P) to total sedimentary phosphorus (TSP) observed
in the present study ranged between 23.40 and 30.56 %, 14.55 and 21.97 %, 3.55 and 12.96 % and 3.55 and 6.3 %
respectively.