Resumen de Effects of farm and commercial inputs on carp polyculture performance: participatory trial in an experimental field station
Martha Hernández, Eucario Gasca Leyva, Pablo Gressler, Dione Krise
The carp polyculture production system is the most widely used system by small-scale fish farmers in southern Brazil (States of Paraná, Santa Catarina and Rio Grande do Sul). The aim of this study was to compare biotechnical and economic parameters between a farm system (FS) using farm inputs (chicken manure, maize and grass) and a commercial system (CS) using commercial inputs (triple super phosphate, ammonium nitrate and balanced food) feeding to apparent satiation. The experiment was carried out for 196 days in earthen ponds of 500 m2 , with three replicates per system. The stocking density was 2,000 fish ha-1, consisting of 35% grass carp (Ctenopharyngodon idella), 30% of mirror common carp (Cyprinus carpio var. specularis), 20% of bighead carp (Aristichthys nobilis) and 15% silver carp (Hypophthalmichthys molitrix). In both systems, a low level of total phosphorus in water (0.06 mg L-1) and in the sediment (4 mg L-1) was observed. Production was significantly increased in the CS (76 kg 500 m-2 196 days-1) than in the FS (43 kg 500 m-2 196 days-1). Costs and revenues were higher in the CS and profits were similar in the two systems. Similar profits do not mean that CS is necessarily more convenient. Advantages and drawbacks for small-scale farmers considering labor, land and availability of money are discussed.
