Abstract

In this study, the liquid digestate (LD) from an anaerobic baffled reactor (ABR) treating starch wastewater (SW) was used as a low-cost biofertilizer for the cultivation of Shanghai cabbage, a common Chinese vegetable. A greenhouse randomized pot experiment was conducted to evaluate the following: the effect of urea (UN), SW and liquid digestate (LD) on the yield and NO3− and NO2−content of the vegetable; NH4+, NO3−, total dissolved nitrogen (TDN) and dissolved organic carbon (DOC) of the soil; and N2O emissions during the experimental period. SW was used for three treatments (100, 200, or 300 ml per pot per application) and LD for six treatments (50, 100, 150, 200, 250 or 300 ml per pot per application). Our results showed that LD significantly increased the vegetable yield. Application of 200 ml of LD provided 41.5% higher yield than UN application. Furthermore, the NO3− content of LD-treated vegetables was 2.40–42.83 times lower than that of UNtreated vegetables. LD treatment also reduced the risk of N leaching from the soil, and the total N2O fluxes (FPV 30) per tonne fresh weight of vegetable for LD 4 were about 39.8% lower than those of the UN. Thus, LD was found to be a feasible low-cost biofertilizer alternative to UN for sustainable vegetable farming.