Biochar for urban agriculture: Impacts on soil chemical characteristics and on Brassica rapa growth, nutrient content and metabolism over multiple growth cycles

Shuang Song, Srishti Arora, Anna Karen C. Laserna, Ye Shen, Brian W.Y. Thian, Jia Chin Cheong, Jonathan K.N. Tan, Zhongyu Chiam, Siew Lee Fong, Subhadip Ghosh, Yong Sik Ok, Sam F.Y. Li, Hugh T.W. Tan, Yanjun Dai, Chi Hwa Wang

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)

Abstract

With possible food crises looming in the near future, urban farming, including small-scale community and home gardens for home consumption, presents a promising option to improve food security in cities. These small-scale farms and gardens often use planter boxes and raised beds filled with lightweight soil or potting mixes. While previous studies on biochar focused on its application on large-scale contiguous farmlands, this study aimed to evaluate the suitability of biochar as a partial soil substitute to produce a durable and lightweight soil-biochar mix for small-scale urban farms. The effects of biochar on the chemical properties of the soil-biochar mix, crop yield and, particularly, crop nutrients and metabolic content were assessed. A germination test using pak choi seeds (Brassica rapa L. cultivar group Pak choi, Green-Petioled Form) showed that the biochar contained phytostimulants. Through a nursery pot experiment over four growth cycles, biochar treatments performed better than pure soil at retaining water-soluble NO3 and K+ ions, but were worse at retaining PO4 3− ions. Nonetheless, despite its positive effect on soil NO3 retention, biochar application did not improve crop yield significantly when the application rate varied from 0% to 60% (v/v). Untargeted metabolomic analyses showed that biochar application may increase the production of carbohydrates and certain flavonoids and glucosinolates. The results of this study showed that biochar can potentially be used to improve pak choi nutritional values and applied in large quantity to obtain a lightweight soil mix for urban farming.

Original languageEnglish
Article number138742
JournalScience of the Total Environment
Volume727
DOIs
Publication statusPublished - 2020 Jul 20

Keywords

  • Flavonoids
  • Glucosinolates
  • Kaempferol biosynthetic pathway
  • Leafy vegetables
  • Untargeted metabolomics

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • Waste Management and Disposal
  • Pollution

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