What influence do carbon compounds have on the growth of biofilm?

Organic substances are increasingly discussed in the horticultural sector, and the term carbon compounds is regularly mentioned. But what are carbon compounds?

In short, they are compounds that consist mainly of carbon atoms. Carbon compounds are also referred to as organic compounds, but that is not the whole picture.

Nature
A carbon atom can enter into four different compounds at a time. Because of that, millions of carbon compounds are possible, like a sort of Lego for adults. Here are a few to paint a clear picture. In nature, pure carbon appears in the form of diamonds, but charcoal is also a form of carbon. Us humans also consist of carbon, the building materials of a plant are comprised of carbon compounds, drippers (plastic) are also made of carbon. The list goes on.  

In greenhouse horticulture, many products are used that have carbon compounds in them. These substances are dosed in irrigation water, such as: fertilizers, organic stimulants, chemical and organic crop protection, and disinfection products.  

What follows are a few substances known within horticulture, including the carbon levels:

Examples of carbon compounds in irrigation water

Substance Function % carbon
DTPA chelate in iron fertilizer  42%
Salicylic acid active substance for crop defense 60%
Thiacloprid chemical crop protection  47%
Trichoderma harzianum biological crop protection living organism
Humic acid biostimulant 55%
Amino acids biostimulant 34%

Examples of carbon compounds used in desinfectants 

Substance Function % carbon
Benzoic acid surface desinfection 68%
Formaldehyde surface and room desinfection 40%
Humic- and fulvic acid hand desinfection 52%

One hundred percent organic carbon (TOC)
Throughout the year, the carbon levels can fluctuate from 5 to 140 milligrams per liter. This is mainly due to the dosing of fertilizers, crop protection products, and organic stimulants in the experience of van Cindro Agro Consultancy. “With one hundred percent organic carbon values (TOC-values) above 100 milligrams, biofilm develops very fast, which is why the watering system needs to be treated with a low dose of disinfectant preemptively. Curative treatment (removal of) is also a possibility, but be aware of clogging caused by the excessive dosing with active ingredients, which can lead to the biofilm releasing too fast.”

Frequent used substances in irrigation water Dosage Carbon in irrigation water by shock-dosage
I-Amino acids 200 ppm (2-4 ltr/ha/7-14 days 68 mg/l
Humine- and fulvine acids 200 ppm (2-4 ltr/ha/7-14 days 110 mg/l
Saliyclic acids 1 ltr/ha/7 days 7-14 mg/l

At TOC values over 100 mg, biofilm develops rapidly. Source: Goed Gietwater, Wageningen University & Research

Are carbon compounds the problem?
What is the advice for growers given the explanation previously provided? According to Cindro Agro Consultancy, there is no single piece of advice for the entire horticultural sector. “As tried to explain before, carbon compounds are present in many different substances such as Trichoderma spp, benzoic acid, and the daily used hand disinfectant.”

The photo on the right: an example of biofilm in the pipes 

The question is if this really causes the growth of bacteria and/ or development of biofilm? One thing is certain: it is too simplistic to say that carbonaceous compounds accelerate the growth of biofilm simply because there are many carbonaceous compounds used by growers. More research into specific products could provide a definitive answer.

If growers still have questions about this topic and/ or would like to receive advice, Cindro Agro Consultancy is happy to help.

For more information: 
Cindro Agro Consultancy Ltd.
Thomas Verburg
info@cindro.nl 


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