Ameliorating Coastal Salt-Affected Soils: The Role of Biochar, Acid-Modified Biochar, and Wood Vinegar
Introduction
Coastal saline-alkali soils face severe degradation due to pollution, urbanization, and economic activities, making them less productive for agriculture. Traditional soil amendments have limitations such as high costs and inefficiency. Biochar, acid-modified biochar (ABC), and wood vinegar (WV) have shown potential as soil amendments, but their effects on coastal saline-alkali soils remain largely unexplored. This study investigates their individual and combined impact on soil salinity, nutrient availability, and microbial communities.
Experimental Design and Application
Biochar, ABC, and WV were prepared from poplar wood using pyrolysis. Soil samples were collected from the Yellow River Delta and incubated with different treatments for 45 days under controlled conditions.
- Biochar (BC) and ABC were applied at a rate of 1.5% (w/w).
- Wood Vinegar (WV) was diluted at 1:500 and applied to the soil.
- Treatments included BC, ABC, WV, BC + WV (BWV), and ABC + WV (AWV), with an untreated soil sample serving as the control (CK).
Soil properties, including pH, nutrient content, and microbial diversity, were analyzed before and after incubation.
Key Findings
Soil pH and Electrical Conductivity
- ABC significantly lowered soil pH (from 8.53 to 8.14), improving conditions for nutrient availability.
- WV had a minimal effect on soil pH, likely due to rapid degradation of organic acids.
- Electrical conductivity (EC) remained stable across treatments, suggesting no significant salt accumulation.
Nutrient Availability
- ABC increased total organic carbon (TOC) and nutrient levels, particularly nitrogen (N) and phosphorus (P).
- Available phosphorus and potassium were significantly higher in ABC-treated soils due to enhanced retention and slow release.
- WV alone had little effect on nutrient levels but showed synergistic effects when combined with ABC.
Soil Microbial Diversity
- Biochar and ABC increased bacterial richness, promoting beneficial microbial activity.
- ABC boosted the presence of Pseudomonadaceae and Sphingomonadaceae, which are crucial for organic matter degradation and nutrient cycling.
- WV alone did not significantly alter microbial communities but, when combined with biochar, enhanced bacterial diversity.
Implications
- ABC is the most effective amendment, improving soil fertility, microbial activity, and reducing alkalinity.
- WV alone is not highly effective but can enhance the benefits of biochar when co-applied.
- The study suggests that biochar and its modifications are promising solutions for reclaiming degraded coastal soils, offering an eco-friendly and sustainable approach to soil remediation.
Conclusion
This research highlights that while WV alone does not significantly impact saline-alkali soils, ABC is a powerful amendment that enhances soil conditions and microbial health. The findings provide valuable insights for sustainable soil management strategies in coastal regions.