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Environment

Food waste converted into bacteria-boosting liquid fertilizer

By Ben Coxworth
January 28, 2021
Food waste converted into bacteria-boosting liquid fertilizer
The fertilizer was made from a feedstock of discarded food from grocery stores, and beer mash
The fertilizer was made from a feedstock of discarded food from grocery stores, and beer mash
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Populations of Pseudomonas bacteria found in a control group of plants (left) and in those watered with the digestate (right)
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Populations of Pseudomonas bacteria found in a control group of plants (left) and in those watered with the digestate (right)
The fertilizer was made from a feedstock of discarded food from grocery stores, and beer mash
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The fertilizer was made from a feedstock of discarded food from grocery stores, and beer mash

Everyone already knows that compost made from food scraps helps plants to grow. Now, however, scientists have fermented food waste to create a liquid fertilizer that boosts the number of beneficial bacteria within the plants themselves, and in their soil.

Led by microbiologist Deborah Pagliaccia, researchers at the University of California-Riverside started with two types of food waste – mash left over from the beer production process, and mixed food items discarded by grocery stores. That waste was subjected to an anaerobic fermentation process, in which microbes rendered it into a liquid known as a digestate.

That liquid was then added to the water used to irrigate citrus plants in a greenhouse. It was a closed-loop irrigation system, meaning that water which ran out of the soil was pumped back around to be used again.

Within just 24 hours of the digestate being added, it was found that populations of beneficial bacteria within the plants and soil were two to three orders of magnitude greater than those in a control group of plants. Such bacteria produce compounds that not only help plants grow stronger and faster, but also make them more resistant to disease.

Populations of Pseudomonas bacteria found in a control group of plants (left) and in those watered with the digestate (right)
Populations of Pseudomonas bacteria found in a control group of plants (left) and in those watered with the digestate (right)

It was additionally observed that carbon levels in the water initially peaked after the digestate was added, then sharply decreased. This suggests that the bacteria were using that carbon to reproduce. And importantly, no harmful microbes such as Salmonella were detected anywhere within the system.

It is now hoped that once the technology is developed further, such fertilizers could reduce the need for or even replace conventional fertilizers, which are more expensive and less eco-friendly. Additionally, the digestate is made from waste that might otherwise simply end up in landfills.

"We must transition from our linear 'take-make-consume-dispose' economy to a circular one in which we use something and then find a new purpose for it," says Pagliaccia. "This process is critical to protecting our planet from constant depletion of natural resources and the threat of greenhouse gases."

A paper on the study was recently published in the journal Frontiers in Sustainable Food Systems.

Source: University of California, Riverside

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EnvironmentUC RiversidePlantsWasteAgricultureBacteriaNew Atlas Audio
5 comments
Ben Coxworth
Ben Coxworth
Based out of Edmonton, Canada, Ben Coxworth has been writing for New Atlas since 2009 and is presently Managing Editor for North America. An experienced freelance writer, he previously obtained an English BA from the University of Saskatchewan, then spent over 20 years working in various markets as a television reporter, producer and news videographer. Ben is particularly interested in scientific innovation, human-powered transportation, and the marine environment.

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5 comments
paul314
So: composting, only fancier?
Chris Coles
First, they only accept registrations from people within their known organisations; no one from any external organisation my register to make a comment.

It is my understanding that almost all generally available food within the United States is contaminated with Roundup, which is well known to have adverse effects upon the human biome. This will, inevitably, apply to waste products from beer manufacture. So the question is; did they make any attempt to research the use of fully organic inputs to their systems? And if so, did they observe any differences in their outcomes from such research? Someone from the study, please advise. Thank you.
buzzclick
How is this different from compost "tea" that people have known about for years?
@Chris Cole, Glyphosate juice is just an added bonus! lol
Karmudjun
Good article Ben, this looks like something small organic farmers could incorporate in their practice. We (all of us who were raised farming) know how to compost and mix things, but rarely have I seen digested material used as fertilizer outside of my home-made methane generator H.S. science project. That effluent was quite a growth simulator even after all the methane was pulled off! Shame there is no information on methodology - ie., the fermentors - in your synopsis. I'll read the resource article.

I do have to caution folks who cite unsupported information or WAG (Wild Ass-Guess) regarding our food supply: The greatest harm from our food supply, esp in the USA, comes from the manufacturer of processed food. The FDA does not quantify most herbicidal compounds in food - glyphosphates are not quantified - the European Union has set an acceptable level well below the USA's standard and do quantify levels - I'll quote from the European Food Safety Authority report here:

The 2016 European Union report on pesticide residues in food, "In total, 50.7% of the tested samples were free of quantifiable residues" . Link below.

I will further caution a previous commenter in WAGs on the characterization of the particular health issues seen in high exposure to only one compound as if it is somehow related to the extremely low exposure noted by eating a balanced diet of USA grown foodstuffs. This is something I am quite familiar with both by profession and heritage - I come from a farming family that still farms.

To date, NHL (non-Hodgkin's Lymphoma has been associated with glyphosphate exposure - HIGH DOSE CHRONIC EXPOSURE. As in 30 years on the farm pre-emergence and pre-harvest application exposure. But other people without high Glyphosphate Based Herbicide (GBH) exposure have been diagnosed with NHL. Since the first definitive diagnosis of NHL, the rates were about 11 per 100K person years. If everyone lived 100 years, then eleven of one thousand people (1.1%) would develop NHL.

Since 1860 when Hodgkin's Lymphoma (HL) was diagnosed & named, 61 forms of non-Hodgkin's Lymphomas have been diagnosed. About 1.4% of the population will develop NHL. But with high exposure to GBH, that goes from slightly more than 1% to a very high 2% (1.1% general population to 1.9% high GBH exposure). With all the chemicals in our modern society, our gut biome is certainly altered. The well known effects of Round-up are the NHL statistics, and are not correlated with gut biome changes. Research continues, but no, round-up is not found in our food supply as you have stated. Yes it is used in most commercial farming - and it is getting less effective since gyphophate resistant broadleafs have developed. It has become an expensive production farming tool. And yes, you can find traces in some processed foods. But in all? WAG!

EFSA J. 2018 Jul; 16(7): e05348. Published online 2018 Jul 25. doi: 10.2903/j.efsa.2018.5348
Sorry for the length, I had to provide data!
Karmudjun
@Buzzclick - That is a great question - if we knew what they used in their model, we could compare. Finished compost should have fungus or yeast/mold that broke down the material, the tea should have a plethora of these bacteria and fungi along with the compost nutrients. It really depends on the fungi utilized in fermenting.