Scientists say $1,000,000 loss is due to glyphosate-induced deficiency in vital nutrients. Report: Claire Robinson
Recently we reported on research showing that glyphosate residues in poultry manure-based fertiliser used by gardeners and organic and conventional growers can ruin yields of tomatoes and other sensitive crops. The glyphosate likely came from pre-harvest “desiccation” (dry-down) of feed grains by the spraying of glyphosate-based herbicides; and the spraying of these same herbicides onto GM glyphosate-tolerant corn and soy, which is used in poultry feed worldwide.
Now a new paper reveals that glyphosate residues in poultry manure caused the loss of $1,000,000 worth of organic sauerkraut in 2022 by making the sauerkraut soggy and therefore undesirable.
The authors of the paper initially focused on differences in fermentation conditions between organic and conventional sauerkraut. But they found that no differences in fermentation conditions accounted for the condition of the organic sauerkraut. So they switched their attention to analysing the mineral content of cabbage grown for sauerkraut production.
They found that the cabbage grown for the organic sauerkraut had a deficiency in critical micronutrients such as iron, copper, manganese, boron, and zinc, compared with the cabbage grown for the higher quality, crisp conventional sauerkraut.
The problem wasn't the soil that the organic cabbage was grown in – while the organic soil did have severe deficiencies in some nutrients, conventional soils planted to cabbage were also deficient in critical nutrients, but still produced good quality sauerkraut. The issue turned out to be that the organic cabbage wasn't taking up the available nutrients from the soil. Some of the organic cabbage was severely deficient in copper, iron, and zinc, high in nitrogen, boron, and sulphur, and sufficient in the other essential nutrients.
The authors write,“This nutrient imbalance caused significant variability in the quality of the organic sauerkraut, with some batches producing soft and mushy sauerkraut that was not marketable, resulting in a loss to the company of $1,000,000.”
This deficiency was traced to the use of poultry manure in the organic cabbage production. The manure was contaminated with glyphosate residue from the genetically engineered feed that the turkeys and chickens were given.
How it happens
The authors explain that glyphosate is a potent mineral chelator – meaning that it bonds with and immobilises mineral nutrients in the soil, making them unavailable to plants. They add that it is also an antibiotic, acting against beneficial soil microbes that help plants absorb nutrients.
They conclude that glyphosate impairs the absorption and physiological function of essential minerals in the shikimate metabolic pathway of the plant whereby cell walls and lignin are produced, thus compromising the structural quality of the sauerkraut.
The sauerkraut itself was not analysed for glyphosate residues because Lactobacillus plantarum, the primary fermenting organism for sauerkraut, has been shown to fully degrade the herbicidal chemical.
How to fix the problem
After this discovery, the researchers investigated various remediation strategies aimed at eliminating glyphosate from the soil and restoring nutrient uptake. Corn grain and silage were selected as the test crops.
Among the tested remediation solutions were raw sauerkraut juice containing Lactobacillus plantarum, which is reported to degrade glyphosate in the rumen of dairy cows, and two patented proprietary microbial mixtures, PB027 and PB027SK, that degrade glyphosate. These treatments were specifically formulated to degrade residual glyphosate in the soil. The results showed that these interventions could reduce soil glyphosate levels by 80% to 90% within 6 to 7 months to significantly enhance both the yield and quality of corn grain and silage.
The increase in corn grain yield from glyphosate degradation on one type of soil was 13.5 bushels/acre). The increase in yield in a second type of soil was 10.8 bushels/acre for corn grain and 2.68 t/acre for silage, with an additional improvement in silage feed quality beneficial for milk production.
The authors conclude that the findings show the importance of addressing both micronutrient sufficiency and glyphosate residue in soil to ensure the optimal growth of cabbage and the quality of sauerkraut produced:“By successfully identifying manure as a subtle source of nutrient immobilisation and implementing effective soil remediation techniques, this research highlights a clear path forward for improving crop yield and quality to ultimately enhance the structural integrity and consumer acceptance of sauerkraut.”
The authors add that the study has broader applications for the nutritional content and crop yields of many organic crops grown with conventional poultry and animal manures that may contain glyphosate from desiccation or the feeding of GM glyphosate-tolerant crops.
The new study: Dieter Harle et al (2024). Saga of soggy sauerkraut. HortScience 59(11). 1 Nov. https://doi.org/10.21273/HORTSCI18041-24