Aquaculture CRSP 21st Annual Technical Report
On-Farm Trials of Different Fertilization Regimes Used in Bangladesh
Tenth Work Plan, Appropriate Technology Research 4B (10ATR4B)
An on-farm trial was conducted in different ecological zones (based on soil types) of Bangladesh during July 2002 to March 2003. The best fertilization regime from the on-station trial conducted during July to December 2001 at Bangladesh Agricultural University (BAU), Mymensingh, Bangladesh, was the BAU fertilization regime. Thus, the purposes of the present on-farm trial were to compare the BAU fertilization regime with the fertilization regimes currently used by the three nongovernmental organizations (NGOs) in Bangladesh and to compare effects of BAU and each NGOsÕ fertilization regime on fish production, water quality, and economic returns. The tested fertilization regimes were BAU fertilization regime: fortnightly application of 1,250 kg cow dung ha-1, 31.25 kg urea ha-1 and 15.625 kg triple super phosphate (TSP) ha-1; PROSHIKA fertilization regime: weekly application of 500 kg quick compost ha-1; Bangladesh Rural Advancement Committee (BRAC) fertilization regime: fortnightly application of 125 kg cow dung ha-1, 37.55 kg urea ha-1, and 18.75 kg TSP ha-1; and Caritas fertilization regime: fortnightly application of 1,500 kg cow dung ha-1. Seven fish species used in the on-farm trial were catla (Catla catla), rohu (Labeo rohita), silver carp (Hypophthalmichthys molitrix), silver barb or as locally called, rajputi (Barbonymus gonionotus), common carp (Cyprinus carpio), grass carp (Ctenopharyngodon idella), and mrigal (Cirrhinus cirrhosus). These species were stocked at ratios of 8:6:10:30:2:2:2, respectively, with overall density of 1.5 fish m-2 in Caritas sites; 4:7:12:10:2:3:6, respectively, with overall density of 1.1 fish m-2 in BRAC sites; and 6:11:11:0:5:2:5, respectively, with overall density of 1.0 fish m-2 in PROSHIKA sites.
There were no significant differences in fish yields between fertilization regimes at any site (P > 0.05), but there were significant differences in yield between sites (P < 0.05). The highest yields were achieved by both PROSHIKA and BAU fertilization regimes at the PROSHIKA site. At this site ponds were stocked at similar density and with catla, rohu, silver carp, common carp, grass carp, and mrigal. However, the PROSHIKA site used different ratios of species than in the on-station trials. The production cost was highest for the PROSHIKA fertilization regime, and the highest net return was achieved by the BAU fertilization regime at the PROSHIKA site. The trials at the Caritas and BRAC sites used an additional species (silver barb) and higher overall stocking densities, and both of these changes did not result in any higher fish yield. Considering fish production, fertilizer input level, and economic return, the on-farm trial indicated that the BAU fertilization regime was the most appropriate for carp polyculture ponds in Bangladesh, while low-cost options such as the BRAC fertilization regime may be suitable for resource-poor, small-scale rural farmers.
Bangladesh is one of the most densely populated countries in
the world. Fisheries and aquaculture in particular are vital to BangladeshÕs national economy in terms of nutrition, income, employment generation, and foreign exchange earning (Alam