Comparison of efficacies of peanut shell biochar and biochar-based compost on two leafy vegetable productivity in an infertile land

The soils in northwest China are severely stressed with nutrient deficiency and water depletion, thus limiting crop production and sustainable agricultural development. Biochar-based amendments, tailored for specific soil issues, have raised great public interest for soil improvement and carbon sequestration. Peanut shell-derived biochar (PBC) and PBC-based amendment (PAD) obtained from composting were added at concentrations of 0%, 1.5%, 3%, and 5% (w/w) into light sierozem soil to compare their effects on growth of crown daisy (Chrysanthemum coronarium L.) and leaf lettuce (Lactuca sativa var longifoliaf L.). PBC had no significant effect on the yields of the two vegetables due to the second season growth, while addition of low concentrations of PAD (≤3%) significantly increased their yields by 15.8%–107%. The positive effect of PAD was primarily attributed to the improved soil qualities (e.g., water holding capacity (WHC), soil organic matter (SOM), electrical conductivity (EC)) and increased contents of available macronutrients (e.g., P and K), and micronutrients (e.g., B, Zn and Mn). However, addition of 5% PAD decreased the yield of crown daisy by 26.9% compared to that grown in untreated soil because of surplus nutrient input resulting in high EC. Overall, our findings demonstrated that the designed PAD synthesized from PBC compost had the potential to ameliorate the infertility in the soil and thus to improve vegetable yield.