Efficacy of vegetable waste biogas slurry on yield, quality and nitrogen use efficiency of cauliflower

Biogas slurry can be used as a nitrogen (N) fertilizer, and has been suggested to reduce chemical fertilizer input and improve vegetable quality. The present study aimed to evaluate the effects of vegetable waste biogas slurry topdressing on the yield, quality and nitrogen (N) use efficiency of cauliflower. 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) was conducted. When compared with that of the CON treatment, the HBS, BS, and DBS treatments increased the yield of cauliflower by 4.7%, 13.7%, and 15.3%, respectively. Furthermore, the BS and DBS treatments improved cauliflower quality compared with that of the CON treatment. The HBS and BS treatments increased the N use efficiency and the DBS treatment reduced the N use efficiency compared with that of the CON treatment. Considering the increased fruit quality and N use efficiency, 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.