Wheat and maize growers farming saline or alkaline soils have new research to consider — a two-year field trial published in the Journal of Soil Science and Plant Nutrition found that wood vinegar applied as a foliar spray increased wheat yields by 12.4 to 44.3% and maize yields by 6.8 to 13.7% in a saline-alkali cropping system. The research also found wood vinegar enhanced fertiliser efficiency, with nitrogen utilisation significantly improving when wood vinegar was combined with urea humate.

The trial was conducted over two consecutive seasons on saline-alkali soils using a wheat-maize rotation — one of the most common broadacre cropping systems. Seven treatments were tested, combining three rates of urea humate (none, 50%, and 100%) with and without foliar wood vinegar applied at 90 litres per hectare. A no-nitrogen control was included as a baseline.

The yield results were notable. Wood vinegar applied alone — without urea humate — produced wheat yield increases of 12.4 to 44.3% depending on the season. Maize yields increased by 6.8 to 13.7%. When wood vinegar was combined with urea humate, nitrogen use efficiency improved significantly relative to urea humate alone, pointing to a synergistic effect between the two inputs.

The soil biology findings were equally significant. Compared to the no-urea-humate treatment, microbial biomass carbon increased by 9.8 to 24.9% and microbial biomass nitrogen by 18.1 to 29.2% by the end of the two-year trial. Urease activity — an enzyme involved in nitrogen breakdown that can drive nitrogen losses when elevated — decreased by 16.6 to 25.0%. At the same time, mineral nitrogen in both ammonium and nitrate forms increased through the top 40 centimetres of the soil profile, indicating improved nitrogen availability for plant uptake.

For dryland and irrigated grain growers managing saline or sodic soils, the combination of factors here is practically significant. Saline-alkali soils constrain microbial activity, nitrogen availability, and crop productivity simultaneously. The findings suggest that wood vinegar, particularly when used alongside humate-based fertilisers, may address several of these constraints at once — supporting soil biology, retaining nitrogen in plant-available forms, and reducing enzyme-driven nitrogen losses.

The two-year duration adds credibility to the results, as single-season pot trials often fail to capture soil biology changes that accumulate over time.

Source: Combined Urea Humate and Wood Vinegar Treatment Enhances Wheat-Maize Rotation System Yields and Nitrogen Utilization Efficiency Through Improving the Quality of Saline-Alkali Soils — Sun et al., Journal of Soil Science and Plant Nutrition, 21, 2021 (https://doi.org/10.1007/s42729-021-00477-1)

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Paddy rice growers investigating soil health inputs will find a useful reference point in research published in the Korean Journal of Crop Science, which examined how wood vinegar application affected soil chemical properties and rice growth when combined with rhizosphere microorganisms and fertiliser.

The pot trial tested four factors simultaneously — two soil types, three fertiliser rates, three microorganism types, and two wood vinegar application rates (500x and 1000x dilution) — across 54 treatment combinations. The comprehensive design makes it one of the more thorough examinations of wood vinegar under varying soil and input conditions.

On soil chemistry, wood vinegar at 500x dilution resulted in higher residual total nitrogen in soil compared to untreated controls, regardless of fertiliser level. Slight increases in exchangeable potassium, calcium, and magnesium were also observed with wood vinegar application, particularly at 500x dilution combined with full fertiliser rates. Organic matter levels also showed a slight upward trend with wood vinegar application across different fertiliser rates.

On rice growth and yield, the study found that fertiliser application rate and soil type were the dominant factors — effects that were strong enough to mask contributions from both microbial inoculation and wood vinegar across most growth parameters. The authors note this was partly a consequence of the pot experiment design, where no leaching occurred and nutrient availability was therefore higher than typical field conditions. They explicitly caution that the absence of significant wood vinegar effects on yield under these specific conditions should not be interpreted as evidence against potential benefits, particularly under long-term or field application scenarios.

For Australian rice growers, the soil nutrient findings are the most practically relevant. The research indicates wood vinegar may improve the availability of nitrogen, potassium, calcium, magnesium, phosphorus, and organic matter in paddy soil — potentially supporting soil quality over repeated applications. The authors conclude that further field-based research is needed to fully evaluate these benefits under conditions more representative of commercial production.

This is a peer-reviewed study published in 2015, and its honest reporting of both positive and null findings makes it a credible reference for growers evaluating wood vinegar as a soil health input rather than a standalone yield booster.

Source: Effects of Rhizosphere Microorganisms and Wood Vinegar Mixtures on Rice Growth and Soil Properties — Jeong et al., Korean Journal of Crop Science, 60(3), 2015 (https://dx.doi.org/10.7740/kjcs.2015.60.3.355)

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Turnip growers and vegetable producers take note — a new preprint study published on SSRN reports that wood vinegar application promoted turnip (Brassica rapa var. rapa) growth by enhancing nitrogen uptake and improving photosynthetic activity. The research found wood vinegar enhanced fertiliser efficiency, with treated plants accumulating significantly higher nitrate-nitrogen levels in both leaves and edible roots without additional nitrogen input.

Researchers grew turnip plants in soil treated with wood vinegar solutions at concentrations of 0.001%, 0.01%, and 0.1% over periods of one to six weeks, measuring growth parameters, nitrogen levels, gene expression, chlorophyll content, photosynthetic activity, and glucose accumulation at each stage.

The key findings were striking. Edible root fresh weight increased significantly at the 0.01% application rate after three weeks, with growth promotion continuing through to six weeks. Nitrate-nitrogen concentrations rose significantly in the leaves at three weeks across all application rates, and in the edible roots at both the 0.001% and 0.01% rates after six weeks — without any corresponding increase in potassium, suggesting the effect was specific to nitrogen dynamics rather than a general ionic response.

To understand the mechanism, the researchers examined the expression of nitrate transporter genes — the molecular machinery plants use to absorb nitrogen from soil. Wood vinegar treatment enhanced the expression of both NRT1.1 and NRT2.1 homologs in turnip roots. These two transporters operate across different nitrate concentration ranges, suggesting wood vinegar may broaden the plant’s effective nitrogen uptake capacity rather than simply stimulating a single pathway.

On the photosynthesis side, two-week-old plants treated with wood vinegar showed increased chlorophyll content, higher steady-state PSII quantum yield, and a decreasing trend in non-photochemical quenching. In plain terms: the treated plants were using light energy more efficiently for photosynthesis and wasting less as heat. Glucose accumulation in leaves also increased, indicating stronger carbon assimilation — which the researchers linked to the enhanced edible root development seen at later growth stages.

The authors propose that wood vinegar promotes turnip growth through two coordinated mechanisms: improved nitrogen acquisition via upregulated transporter gene expression, and enhanced photosynthetic carbon assimilation that drives photoassimilate allocation to the storage root. The 0.01% concentration emerged as the optimal rate for edible root promotion in this study.

For Australian vegetable growers, the nitrogen use efficiency finding is the headline result. The research suggests wood vinegar could support nitrogen uptake without increasing fertiliser input — a meaningful outcome given the cost and environmental concerns associated with nitrogen fertilisation. The photosynthetic improvements add a second dimension, pointing to broader effects on plant metabolism beyond simple nutrient availability.

It’s worth noting this study is a preprint and has not yet completed peer review. The findings are preliminary but consistent with a growing body of research examining wood vinegar’s role as a biostimulant across a range of crop species.

Source: Wood vinegar application improves Brassica rapa var. rapa growth by enhancing nitrogen uptake and promoting photosynthetic activity — Nakai et al., SSRN Preprint, 2026 (https://ssrn.com/abstract=6410159)

Interested in learning more about wood vinegar? Order PyroAg now (https://www.pyroag.com/shop/PyroAg-c168051794) or call 1800 PYROAG (1800 796 224).

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