Natural alternative to chemical nutrients in Hydroponics

The use of Hydroponics for vegetable production is apparently nowadays essential to maximize productions and increase yields. Although the technical issues related to production are well researched and discussed, less information is available about the impact of hydroponics on the nutritional status of fresh vegetables and in particular on the level of bioactive substances. A number of factors such as controlling pests and diseases that play a major role in this are the subject of this article. It is again a shame to find that the Dutch government is being whispered by the wrong people and is opting for the bad solution.


With regard to the nutrients currently used within hydroponics, a new necessary development is needed, namely the bio-hydroponics. Partly because of the depletion of the available raw materials and partly because the demand will increase enormously in the coming years. That is why the gap must be bridged between mineral and organic plant food. The most important thing is a different view of what nutrition means. Strictly speaking, there are in addition to the absence of bioactive substances (bioactive compounds can be defined as essential and non-essential compounds that occur in nature as part of the food chain and with a positive effect on human health. Bioactive compounds consist of chemicals that occur in small amounts in plants (in leaves, roots, shoots, bark and foods such as fruit, vegetables, nuts, oils and grains) also many other elements such as BRMs (biological response modifiers) specific to every herb or vegetable that is not present, or the lack of salvastrols, etc.

Disinfect and sterilize

Disinfecting the hydroponics system to prevent the risk of diseases in plants makes sense. In a hydroponics system, these plant diseases are usually caused by microbial stress, arising from the nutrient solutions or by environmental pollution. Technologies available for disinfection include chemicals (monochloramine, chlorine, chlorine dioxide, iodine, copper ionization, copper salts, silver ionization, ozone, hydrogen peroxide, peroxyacetic acid, ammonium disinfectants), non-chemical or physical treatments (filtration, heat, steam, sonication and ultraviolet radiation) , ozone) and ecological alternatives such as filters. It is clear that even within hydroponics the increasingly limited use of chemical agents will become necessary. This means that growers must increasingly look for alternatives.

In addition to disinfecting, sterilization often uses bleach, hydrogen peroxide and antibacterial products.

Diseases and plagues

So hydroponics is not free of pests and diseases. The best known are mildew, gray fungus (especially pythium), root rot and of course the necessary insects such as mites, thrips, aphids, whitefly and mosquitoes. Viruses and bacteria (Salmonella, E-coli (STEC), Legionella and Listeria monocytogenes, but also the viruses Hepatitis A and Norovirus) can cause damage. In recent years in particular, you regularly see that large hydroponics suppliers of vegetables are struggling with E-coli. This was particularly the case in America in 2018. The alleged outbreaks in the Netherlands in 2005 and 2011 cost the growers millions. The main victims were cucumbers, lettuce, tomatoes and bean sprouts. On the other hand, the method of growing vegetables in hydroponics by Dutch commercial companies is currently the most safe method of cultivation that exists. The small-scale projects are more sensitive to problems.

Chemical or biological treatment

According to a number of estimates, there are hundreds of so-called natural plant protection products on the market against diseases and / or pests. But the applications of this are still lagging behind in relation to chemical agents. The reason is that the general view among growers is that people are usually only inclined to use such resources if no other resources are available (anymore). It is often argued that ‘it does not benefit then it does not harm’. Recognizable from the human medical world where people often think that way when using natural resources. But apparently this is also a common vision in agriculture and horticulture. It is strange because there are many excellent active products that are purely natural. For example, there are known agents based on coconut oil as an insecticide on the market against thrips. It is based on the substance allicin (a powerful antibiotic) the main component of garlic. This substance drives away the trips. But animals are also used, such as parasitic wasps against the white fly. So apparently natural resources work, but general opinion is still lagging behind or is being pushed into the background by legislation. One reason for this might be that there are parallels with the pharmaceutical industry, forcing industry to use only patented and “investigated” agents. For example, General Hydroponics brought fertilizers and pesticides such as AzaMax on the market with the necessary Monsanto chemicals. The cannabis growers happily sprayed loose. If you look at the background, you’ll see General Hydroponics was purchased by Scotts Miracle-Gro, a convicted corporate criminal who sells Monsanto’s Round-Up and other toxins. And this company also bought the Dutch lighting company Gavita and the Arizona-based hydroponics company Botanicare. So infiltration of the multinationals in the Hydroponics world. It is one of the reasons that natural resources need more attention before the process is too far. When it comes to common pests and insects, there is enough information to be found.

Why do diseases arise?

Environmental factors are one of the main causes of the diseases. The growth environment is often the most important factor that contributes to the outbreak of a disease. Many fungal and bacterial diseases require high humidity or water to successfully penetrate the tissue. This is the reason that ventilation with air movement up and under and over foliage, and good moisture removal, are so important within closed growing areas. But when they are there, growers prefer to choose from a wide range of commercial fungicidal or bactericidal spray products, with which they try to exert a quick and direct control. Both approaches can lead to other problems. For example, chemical sprays for fungal problems can cause resistance in populations of pathogens, making the product no longer effective after just a few applications. This is a known phenomenon. Currently, the brown rugose fruit virus in tomato growing is a dangerous virus that appears to be resistant. So why not ask yourself, “why does this plant react in this way?” Plants have their own defense strategies when it comes to the prevention of disease infections. In fact, most fungal spores and bacterial pathogens present in a growing environment never really cause a significant disease outbreak.

Prevention: the first and most important step.

A healthy, stress-free crop has a much lower risk of pests or diseases. Problems will always affect the weakest plants first. If growers can ensure that a larger part of their crop is healthy and strong, there is less need to use other resources. The following basic principles are important:

  1. Water: Additives and other unnatural compounds in tap water can contaminate food solutions. Chlorine dioxide is used in some municipal treatment plants such as PWN and Evides. Abroad it is often normal that it contains chlorine. But other chemicals can also influence the plants in different ways.
  2. pH test: If the pH of your nutrient solution is outside the healthy range, your plants can become malnourished, which means weakness. Many plants need a pH of 5.5 to 6.5 to efficiently absorb nutrients. Keep in mind that synthetic fertilizers – rich in salts – lower the pH.
  3. Do not keep things clean. If you set up hydroponics and make the area around it messy and dirty, you can increase the risk of spreading diseases or pests to your hydroponics system.
  4. It is well known that nutritional deficiencies or malnutrition can affect immune functions. On the other hand, there are increasing indications that for certain nutrients, increased intake above the currently recommended levels may help to optimize immune functions. This can improve the immune function and thus the resistance to infections, while maintaining tolerance. The roots do play the most important role in a complex process, and this is precisely why hydroponics is eminently suitable.

Helping prevention with Colloidal Silver

In the Netherlands there is fortunately a company that distinguishes itself completely from other companies by developing nature-based products that directly stimulate the natural immune response of the plant.

You may have heard of colloidal silver. It is not so well known in the agricultural and horticultural sector, but some people use it when they feel a sinus infection, while others use colloidal silver to treat skin complaints and infections caused by bacteria, yeast, viruses or parasites. It is therefore known as the ‘antibiotic of nature’. It is therefore no surprise that colloidal silver can offer preventative therapeutic and healing properties to our plants and gardens.

The knowledge about this on the well-being of humans, animals and plants is centuries old. In the past every doctor had a personal supply of silver in his doctor’s bag. Until 1999, colloidal silver was seen in America as a “pre-1938 medicine” and as such it could also be used and sold as a medicine. But times are changing and from the horticultural perspective this may offer new possibilities. Instead of a quick solution, this can be a solution without harming the plants, the useful pollinators or the people who consume the fruits or vegetables. Because in the end nobody wants extra chemicals in their dinner or their fruit. The great thing about using colloidal silver in cultivation is that it is very safe for both plants and people. Only excess harms. That is why it must be used with caution, targeted at bacteria, parasites and other pathogens. In addition, you must be sure that you are using real colloidal silver and not silver protein or ionic silver, as some forms can be toxic.

Strictly speaking, silver is an antimicrobial, meaning it can kill harmful microbes. That’s a fact. As so often, there are also two camps in the world who contradict each other in this case. But it is a fact that scientific studies have been done. ( Silver is considered an antibacterial agent with a known mode of action, and its bacterial resistance is well described. The development of nanotechnology in particular yielded various methods for altering the chemical and physical structure of silver, which may increase its antibacterial potential. It also emerged that the physico-chemical properties of silver nanoparticles and their interaction with living cells differ considerably from those of silver ions. Moreover, the diversity in the shapes and characteristics of different silver nanoparticles is also responsible for differences in their antibacterial action and probably bacterial resistance mechanism. And from that comes the difference in the two visions. You cannot really compare silver with colloidal silver.

What is colloidal silver anyway?

Colloidal minerals are composed of single large molecules or groups of small molecules in a solid, liquid or gaseous state. Colloids do not dissolve in a pure solution and are unable to pass through the cell wall. The colloidal minerals floating in a liquid are unable to conduct electricity, and are not involved in bio-electrical activities in the plant. The dictionary indicates that a colloid “is a substance made from ultra-fine particles that are in some form of suspension or solution.”

The ultra-fine particles in a colloid are approximately one hundred thousandth to ten millionths of an inch (0.65 nanometers). Such fine particles are still larger than most molecules. The boundary between the molecular and colloidal degree of distribution cannot be precisely determined. The reason for this is that the transition from roughly dispersed systems to molecularly dispersed systems is a continuous process. Colloidal silver has a concentration of 10 ppm.

A colloidal system must meet the following three characteristics:

First, it must be heterogeneous (i.e., it must consist of disparate ingredients or components, such as silver and water); second, the system must be multi-phase (meaning it must have more than one phase, such as solid, gas, liquid); and third, the particles must be insoluble (meaning that they do not dissolve in the suspension and do not conduct the electricity). Each of these three properties interacts with the other and gives colloids their unique qualities. Colloidal suspensions with metal ions sometimes have distinct advantages over pure solutions. Silver nitrate in pure solution, for example, reacts hostile with body tissues and body fluids because of its corrosive reaction and often does more harm than good. Metallic silver in a colloidal suspension, on the other hand, delivers silver ions in such an amount that it has a harmful effect on microorganisms, such as viruses, fungi, yeasts and bacteria. This is slow enough not to irritate the tissue. Therefore, colloidal silver can be administered directly to plants without any irritation. In contrast, silver nitrate in a pure solution can cause an corrosive reaction.

Operation Colloidal Silver

Colloidal silver acts as a catalyst and reportedly eliminates the enzyme that single-cell bacteria, viruses and fungi need for their oxygen metabolism. (1) In particular, the interaction with the inner membrane of the bacterium is one of the most important mechanisms of Ag + toxicity. It separates the cytoplasmic membrane (CM) from the cell wall within thirty minutes in both gram-positive and gram-negative bacteria, after which it binds to components of cytoplasm, proteins and nucleic acids. Spraying colloidal silver on plants infected with bacteria, fungi and viruses has the consequence that these unwanted organisms quickly suffocate and decay; all without the negative effects of traditional pesticides. And unlike antibiotics, pathogens, viruses, fungi and bacteria do not develop immunity to these silver nanoparticles.

Colloidal silver is a safer and more natural alternative to the many toxic substances that are marketed for gardens and farmers under the flag of crop protection. Colloidal silver is essentially pure water with enclosed ultra-small nanoparticles of silver. The American Environmental Protection Agency (EPA) calls this silver an oligodynamic biocide, meaning that it attacks primitive life forms, but does not harm adult organisms. No damage to bees, ladybirds and other useful insects.

How to use

  1. With large fruits and vegetables

In a study published in the March 2010 issue of the journal Mycobiology, the roots of green onions were treated with silver nanoparticles to eradicate Sclerotium cepivorum fungal infections. In addition to clearing the fungus, the silver increased both the fresh weight and the dry weight of the onions, producing larger, more desirable bulbs. When you have sprayed colloidal silver on your plants, you can sleep peacefully because you know that there is no residue left. Colloidal silver can also be combined with water and vinegar to create a fruit and vegetable wash. A solution of 1 tablespoon of colloidal silver to 1 liter of water is often used. Colloidal silver in hydroponics works well to eradicate root rot. (2)

  1. Water Purification

Colloidal silver has a unique ability to purify the water supply and reservoirs. Several airlines use silver water filters to keep water-related illness in the air. The purification process removes bacteria and algae from the water, as evidenced by the originally intended purpose of the release of silver ions; killing bacteria in the drinking water supply on the Apollo spaceship. With the help of colloidal silver you can ensure in your water collection system that the water is free from bacteria, algae and pathogens.

  1. Limiting damage

Colloidal silver (Argentum) is an ethylene blocker and prevents ethylene from acting as an autocatalyst to build up ethylene levels. This is especially interesting in the case of hail damage and bud and flower drops, which prolongs the flowering period. Minerals play an important role in strengthening plant cells, in particular: phosphate, nitrogen, calcium, silicon, boron and magnesium. A number of products that are available as fertilizer also stimulate the immune system of the plant by, among other things, increasing the production of salicylic acid.

  1. Extend storage and shelf life of tomatoes, apples and grapes

Spraying tested tomatoes and fruit with an appropriate antibacterial silver water solution delayed the appearance of symptoms of microbiological decay almost twice. The authors demonstrated that washing of lettuce with water mixed with nano silver and hydrogen peroxide was more effective than washing with chlorinated water. Silver at 50 ppm caused a significant reduction of microorganisms on the day of washing. The 125 ppm concentration resulted in a 49% reduction in microorganisms compared to a sample washed with water only. According to the authors, only 0.5 ppm of silver is sufficient to reduce the number of Pseudomonas by 0.7 log, while the use of chlorine in a concentration of up to 125 ppm has not produced any significant effects. Enterobacteriaceae also appeared to be sensitive to a small amount of silver. Only 0.1 ppm already caused a reduction of 50% of these bacteria on the day of washing the samples, while at a concentration of 125 ppm after 4 days of storage a reduction of 3.72 log compared to samples that were washed with water were washed. (3)

Other substances discussed in another article are, for example, salicylic acid and micro-copper.

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© Ed van der Post

(1) Mechanistic Basis of Antimicrobial Actions of Silver Nanoparticles Tikam Chand Dakal,1,* Anu Kumar,2 Rita S. Majumdar,3 and Vinod Yadav2, Front Microbiol. 2016; 7: 1831.

(2) The Effect of Nano-Silver Liquid against the White Rot of the Green Onion Caused by Sclerotium cepivorum. Jin-Hee Jung,1 Sang-Woo Kim,1 Ji-Seon Min,1 Young-Jae Kim,1 Kabir Lamsal,1 Kyoung Su Kim,corresponding author2 and Youn Su Leecorresponding author. Mycobiology. 2010 Mar; 38(1): 39–45.

(3)(Ekielski, Adam & Rak, Co & Obiedzinski, Mike & Biller, Elzbieta & Gуrnicka, E.. (2015). APPLICATION OF SILVER NANOPARTICLES TO FRUITS AND VEGETABLES TO IMPROVE THEIR POST-HARVEST SHELF LIFE. 10.5593/SGEM2015/B61/S25.039. )