Cold Plasma and Pyroligneous Acid Boost Wheat Yield and Quality while Improving Soil Fertility

Introduction

With the increasing need for sustainable agricultural practices, researchers are investigating alternative methods to improve crop productivity while minimizing environmental impact. A recent study published in Scientific Reports explores the potential of combining cold plasma treatment of seeds with biorefinery waste products, including pyroligneous acid, biochar, and azolla compost, to enhance winter wheat (*Triticum aestivum*) growth, yield, and soil quality.

Why Cold Plasma and Biorefinery Waste Products?

Cold plasma, an ionized gas containing reactive oxygen and nitrogen species, has been shown to enhance seed germination, photosynthesis, and stress tolerance by modifying seed surface properties and biochemical activity. Meanwhile, biorefinery byproducts—such as pyroligneous acid (PA), biochar, and azolla compost—are valued for their ability to improve soil structure, enhance microbial activity, and increase nutrient availability. This study sought to determine whether these treatments could provide a synergistic effect in wheat production.

Experimental Design and Application Methods

The study was conducted over two cropping seasons (2016-2018) at the Agricultural Research Station of Tarbiat Modares University, Tehran, Iran, using a randomized complete block design with four replications. The treatments included:

  • Cold Plasma (CP): Seeds were exposed to radio-frequency (RF) plasma for 180 s at 50 W before sowing.
  • Pyroligneous Acid (PA): Applied as a soil amendment at 0.04 L/m² before planting.
  • Biochar (BC): Incorporated into the soil at 0.5 kg/m² before planting.
  • Azolla Compost (AC): Added at 0.7 kg/m² before planting.
  • Combination Treatments: CP was tested in combination with PA, BC, and AC.
  • Control: Wheat was grown without any amendments.

The effects of these treatments were evaluated by measuring plant photosynthesis, grain yield, and content of chlorophyll, carotenoids, anthocyanin, protein, and starch.

Key Findings

Effects on Wheat Growth and Yield

  • Grain Yield: The combination of CP and PA resulted in the highest yield increase (+40.0%) compared to the control. CP alone increased yield by 21.3%, while PA alone increased yield by 25.7%.
  • Photosynthesis Rate: CP + PA significantly enhanced net photosynthesis (+39.3%) and total chlorophyll content (+48.3%). CP alone increased net photosynthesis by 19.5%, while PA alone increased it by 22.7%.
  • Protein and Starch Content: CP + PA and CP + AC significantly increased grain protein (+35.0%). CP + BC significantly increased grain starch content (+36.8%). CP alone increased grain protein by 18.2% and PA alone by 22.1%.

Effects on Soil Properties

  • Nutrient Availability: CP + PA significantly increased available phosphorus, zinc, iron, and calcium in the soil. CP alone increased available phosphorus by 12.4% and zinc by 9.8%, while PA alone increased phosphorus by 14.2% and iron by 11.3%.
  • Microbial Biomass: Azolla compost treatments led to the highest increase in microbial biomass nitrogen (MBN, +29.0%). Biochar + CP increased microbial biomass carbon (MBC, +16.0%). CP alone increased microbial biomass nitrogen by 14.6% and PA alone by 17.8%. PA alone also increased microbial biomass carbon by 12.3%, indicating enhanced microbial activity in PA-treated soil.

Implications for Wheat Cultivation

The findings highlight the potential of combining cold plasma seed priming with biorefinery waste amendments to enhance both wheat yield and soil quality. The study demonstrates that CP-treated seeds exhibited superior growth and productivity, particularly when combined with pyroligneous acid and biochar, suggesting that these treatments improve nutrient uptake and plant metabolic activity. Additionally, azolla compost played a crucial role in enhancing soil microbial biomass, further supporting plant health.

By leveraging cold plasma and organic soil amendments, this approach offers a sustainable alternative to synthetic fertilizers, reducing the environmental impact of wheat cultivation while improving food security and soil fertility. Future studies should investigate long-term field applications and potential scalability of these treatments in diverse agricultural settings.

Article based on: Eco-Friendly Approach to Improve Traits of Winter Wheat by Combining Cold Plasma Treatments and Carbonization of Subtropical Biomass Waste