Biochar and Wood Vinegar Boost Peanut Yields in Challenging High-pH Coastal Soil

Introduction

Coastal soils present significant challenges for agriculture due to high salinity, poor permeability, and nutrient deficiencies. A recent study published in *Environmental Technology & Innovation* explores how the combined application of biochar (BC) and pyroligneous acid (PA) improves peanut yield, soil properties, and microbial activity in these challenging environments.

Why Use Biochar and Pyroligneous Acid?

Biochar is known for its ability to improve soil aeration, increase water-holding capacity, and retain nutrients. However, its alkaline nature can be problematic in already high-pH coastal soils. Pyroligneous acid, a byproduct of biochar production, contains organic acids, phenols, and trace minerals that can help adjust soil pH, inhibit nitrogen loss, and enhance microbial activity. The study hypothesizes that combining these amendments could provide synergistic benefits for peanut production.

Experimental Design and Application Methods

The experiment was conducted in a greenhouse using coastal soil from the Yellow River Delta, China. Researchers tested four treatments with four replicates:

  • CK (Control): No amendments.
  • PA: 0.2% (w/w) pyroligneous acid applied to the soil three times at 30-day intervals after seedlings reached the 3–4 leaf stage.
  • BC: 1% (w/w) biochar mixed into the soil before planting.
  • BC+PA: Combination of 1% biochar and 0.2% pyroligneous acid, applied as per the BC and PA treatments.

Peanut plants were grown for 150 days, after which biomass, pod yield, and soil properties were analyzed. Soil microbiome changes were also assessed using high-throughput sequencing.

Key Findings

Peanut Yield and Quality Improvements

  • Higher Pod Yield: The BC+PA treatment increased average pod weight per plant by 15.05%, total pod number per plant by 45.22%, and total peg number per plant by 44% compared to the control.
  • Amino Acid Enhancement: The BC+PA treatment significantly increased the levels of essential amino acids such as leucine, lysine, and valine in peanut kernels, improving their nutritional quality.
  • Better Photosynthesis: Leaf chlorophyll and carotenoid contents were significantly higher in the BC+PA treatment, indicating improved photosynthetic efficiency.

Soil Property Improvements

  • Nutrient Availability: BC+PA increased soil nitrate-nitrogen (NO₃⁻-N) by 48.3% and ammonium-nitrogen (NH₄⁺-N) by 19.8% in the rhizosphere, supporting plant growth.
  • Water Retention: While biochar alone slightly increased water-holding capacity, the combined BC+PA treatment improved soil structure and moisture retention more effectively.
  • Salinity Management: The electrical conductivity (EC) was significantly lower in PA-treated soils, helping mitigate salt stress.

Microbial Community Enhancements

  • Boosted Beneficial Microbes: The BC+PA treatment increased the abundance of beneficial bacteria such as *Arthrobacter*, *Sphingomonas*, and *Blastococcus*, which contribute to nutrient cycling and plant health.
  • Fungal Changes: PA and BC+PA treatments enriched beneficial fungi like *Humicola* and *Chaetomium*, known for their biocontrol properties.
  • Stronger Microbial Networks: Co-application intensified bacterial community interactions, promoting a healthier soil microbiome.

How the BC+PA Combination Works

  • pH Balance: PA's acidity counteracts biochar's alkalinity, stabilizing soil pH.
  • Nutrient Retention: BC adsorbs nutrients, while PA enhances their bioavailability.
  • Microbial Synergy: PA stimulates microbial activity, while BC provides a stable habitat for beneficial microbes.

Implications for Coastal Agriculture

This study demonstrates that biochar and pyroligneous acid can be used together to significantly enhance peanut production in coastal soils. By improving soil fertility, nutrient availability, and microbial activity, this combination offers a promising strategy for reclaiming degraded coastal lands and boosting food production sustainably. Future field studies will be needed to confirm these results under real-world conditions.

Article based on: Co-Application of Biochar and Pyroligneous Acid Improved Peanut Production and Nutritional Quality in a Coastal Soil