Short-term applications of liquid organic fertilizer from fermented fish residue had adverse effects on the soil and leafy vegetable qualities

Abstract

Fermented fish residue (FFR) is a major byproduct generated from the fermented fish sources industries and has the potential to make liquid organic fertilizer. This study aims to determine the chemical properties of the FFR and OF derived from the FFR and to investigate the short-term application effects of the OF on the qualities of soil and leafy vegetable. Three cropping seasons of leafy vegetables (lettuce: Lactuca sativa) were conducted in a field experiment with five treatments consisting of liquid chemical fertilizer (IF) and various doses of the OF with water ratios of 1:100, 1:200, 1:500, and 1:1000. The FFR and OF were acidic and contained elevated amounts of N, EC, and Na but low in P, K, and potentially toxic elements. Applying high OF concentrations caused lower soil pH and exchangeable forms of Ca and Mg, but it enhanced available Fe, exchangeable sodium percentage, and exchangeable Na in soil. Short-term application of the OF had the potential risk of causing soil salinity and sodicity. Moreover, adding higher OF concentrations adversely impacts Na accumulation and K reduction in plants. Therefore, this study proposes that the FFR should not be used for OF production unless its Na is reduced.