Wood Vinegar and Rhizosphere Microbes Enhance Rice Yield and Paddy Soil Quality

Introduction

The sustainability of rice production faces numerous challenges due to the intensive use of chemical fertilizers and conventional farming practices. These practices can lead to soil degradation and reduced long-term productivity. To address these issues, researchers have explored alternative solutions such as rhizosphere microorganisms and wood vinegar (pyroligneous acid). A study published in the Korean Journal of Crop Science investigates how these treatments, applied individually and in combination, influence rice growth and soil properties.

Experimental Design and Application

The study employed a four-factorial pot experiment conducted at Kyungpook National University, South Korea. The key factors tested were:

  • Soil Type: 100% paddy soil vs. a 1:1 mixture of paddy soil and sand.
  • Fertilization Level: 0%, 50%, and 100% of the recommended fertilization rate (RR).
  • Rhizosphere Microorganisms: Inoculation with Bacillus licheniformis, Fusarium fujikuroi, and Rhizobium phaseoli.
  • Wood Vinegar Application: Applied at 0, 500x dilution, and 1000x dilution at a rate of 4 liters per pot.

The experimental setup included 54 treatment combinations, with three replications per treatment under a completely randomized design. Standard agronomic procedures were used to measure plant growth parameters at different growth stages, while soil chemical properties were analyzed after the rice harvest.

Key Findings

Effects on Plant Growth

  • Plant Height: Fertilization had the most significant impact, with plants receiving 100% RR growing the tallest. However, in pure paddy soil, B. licheniformis inoculation combined with 50% RR resulted in plants as tall as those in the 100% RR treatment, suggesting a potential to reduce fertilizer use.
  • Chlorophyll Content: Rhizobium phaseoli inoculation increased chlorophyll levels, likely due to improved nitrogen assimilation. This effect was most notable at 50% RR.
  • Tiller Formation: The number of tillers increased with fertilization but was not significantly influenced by microbial inoculation or wood vinegar application.

Effects on Rice Yield

  • Grain Yield: The highest yields were obtained in the paddy-sand mixture with full RR fertilization. The combined application of wood vinegar and microbial inoculation did not significantly enhance yield beyond the effect of fertilization alone.
  • Panicle and Spikelet Formation: The number of panicles per plant was highest in fully fertilized treatments, while the number of spikelets was generally higher in the paddy-sand mixture.

Effects on Soil Properties

  • Nutrient Availability: Wood vinegar application increased nitrogen retention and improved potassium, calcium, and magnesium availability, particularly at a 500x dilution.
  • Organic Matter Content: Wood vinegar-treated soils had slightly higher organic matter levels, indicating potential long-term benefits for soil health.

Implications

This study underscores the potential of integrating wood vinegar and beneficial microorganisms into rice cultivation. While fertilization remained the dominant factor influencing growth and yield, microbial inoculation showed promise in enhancing plant height and chlorophyll content, particularly at reduced fertilization rates. Wood vinegar improved nutrient availability, suggesting it could be useful for maintaining soil quality in long-term agricultural systems.

However, field-scale trials are needed to validate these findings under real-world conditions. Future research should explore optimal application strategies and interactions between soil amendments, fertilizers, and microbial inoculants to maximize benefits for sustainable rice production.

Article based on: Effects of Rhizosphere Microorganisms and Wood Vinegar Mixtures on Rice Growth and Soil Properties