Eco-economic assessment of rice culture using pisces as alternative method of weed control in Southern Cross River State, Nigeria

This study investigated the ecology and economics of a rice/fish culture system in Calabar, Cross River State, Nigeria. Swamp water rice was cultivated normally as practiced in the study area; in plots of 100 m2 each in which sumps of one tenth of surface area were dug to serve as refuge areas for fish. Four treatments comprised of control (rice cultivation only without any form of weed control), rice only but using Butachlor as chemical weed control method, rice + Oreochromis niloticus and rice + O. niloticus + Heterobranchus longifilis. This experiment had three replicates. Observation showed that there were no significant differences between treatments in some water qualities as temperature, phosphate concentration, alkalinity and total hardness. Ph was higher in control compared to other treatments. Significant differences occurred in nitrates concentration and dissolved oxygen concentration. Plankton count was lower in plots with fish, possibly because of the fish’s grazing actions. The culture system recommended for small scale farmers is the rice + O. niloticus + H. longifilis due to the fact that it could provide higher varieties of food stuff with an increased income to the farmers.