Safe and sustainable fertilization technology with using fish water effluent as a new bio-source for fertilizing

Fish water effluent has great potential to improve agricultural crops. The aim of this study was to evaluate benefits of fish water effluent (FW) as a source of bio-fertilizers coupled with different nitrogen (N) levels on yield, water use efficiency (WUE) and agronomic efficiency of N (AEN) for sprinkler irrigated onion grown on sandy soil. Nitrogen treatments were, 0 (N0), 20 (N20), 40 (N40), 60 (N60) and 80% (N80), kg N ha^-1 of recommended dose. The combined treatments were termed as FW_N0, FW_N20, FW_N40, FW_N60, FW_N80, respectively. This was done along with application of 100% (N₁₀₀) of recommended dose applied from mineral source. FW coupled with different N levels was fertigated periodically from fish ponds via sprinkler irrigation during the whole season of onion. FW coupled with N at 80% of recommended dose (FW_N80) gave comparable yield to N₁₀₀ in the first year while higher yield was obtained in the second year. Similarly, the value of WUE and AEN under FW_N80 was as high as their corresponding value under N₁₀₀ in the first year but the both values were appreciably higher in the second year. These results indicate to the benefits of fish water effluent and the validity and possibility of sustained agronomic performance of onion yield besides reducing 20% of N fertilizer cost.