Effect of biogas slurry on water footprint in cauliflower production

We conducted a field experiment consisting of five treatments during topdressing (CK: no N input, CON: farmer's conventional N fertilizer input, HBS: substitution of half the amount of N fertilizer with vegetable waste biogas slurry, BS: substitution of the total amount of N fertilizer with vegetable waste biogas slurry, and DBS: substitution of double the amount of N fertilizer with vegetable waste biogas slurry) to evaluate the effect of biogas slurry topdressing on the water footprint (WF) of cauliflower. The results showed that The WF of cauliflower production with the BS treatment was the lowest, which was 18%, 15%, 34%, and 52% lower than that with the DBS, HBS, CON and CK treatments, respectively. The main water consumption sources were blue water consumption via irrigation and grey water consumption, and they accounted for 93%~98% of the total water consumption. Considering the increased cauliflower yield, the substitution of fertilizer N with equal amount of vegetable waste biogas slurry during topdressing in the production of cauliflower is recommended in northern China. Water footprint can be reduced by reducing irrigation and nitrogen leaching.