This article was written by Stephen Brookes and originally appeared in Garden Culture Magazine, UK Issue 4.

Taking an interest in organic gardening is usually triggered by wanting to avoid fruits and vegetables that are free of pesticides, or taking better care of the environment. That’s important, yes, but first you’ve got to understand it’s all about the soil and plant roots. Unlike conventional gardening, it’s not about appearances on the surface. They do matter. But take care of the unseen first, and it will take care of you.

What is unique about organic gardening?.

An organic gardener utilizes unadulterated natural substances, and uses carbon as a main ingredient for plant nutrition. Nothing synthetic is used whatsoever in this all natural methodology. When a gardener grows organically, he mimics what has been observed in nature; it can sustain itself with no interference from humans. Decaying organic materials will all eventually have a metamorphosis into a form of carbon. Carbon is commonly known as the “building block of life.” The carbon byproduct is named humus. Humic acid is a well known additive in organic world. Humus is one of the main foods for the members of the soil food web.

What is the soil food web?

The soil web is comprised of a complex variety of microscopic organisms. These organisms are mainly earthworms, protozoa, mycorrhizae (beneficial fungi), nematodes, and beneficial bacteria. A good handful of healthy soil can contains from the tens of thousands to the billions of these symbiotic creatures. They eat humus (carbon), other carbohydrates and proteins (exudates), and even each other! The roots release these exudates in their nighttime cycle. They all colonize mainly in the roots rhizosphere, competing for the exudates.

What is the rhizosphere?

The rhizosphere is the slim area of soil around the roots that is inhabited by the soil food web, and receives the secretions and exudates the roots let off at night. In organic gardening, the rhizosphere helps to give last minute processing to nutrients with the help of the food web. The food web retains much of the nutrient, so it is not immediately lost, as is the case in hydroponics. Think of the rhizosphere as a screen to catch and filter out the nutrient before it passes through in the water. The rhizosphere also is the first line of defense from disease, pathogens, and bad microorganisms before hitting a plant’s root zone. The rest of the soil outside of the rhizosphere is called the “bulk soil”.

I have good soil. How do I get the food web alive and thriving?

Chlorine and chloramines: One of the biggest mistakes novice gardeners make when starting organic farming is using tap water that is saturated in chlorine and chloramines, or mixing in synthetic components with organic counterparts. Chlorine and chloramines kill the soil food web on contact! If not using well water, great care must be taken -either filter the chlorine out, or to let the water sit 24 hours to let the chlorine toevaporate. Chloramines are much more stable, and a special catalytic filter must be used, as a regular carbon filter provides no defense against them, and they will not simply evaporate out. Synthetic fertilizers are sodium based, and have a drying effect on the biology. The salt-based casualties lead to the retreating of the survivors ending the natural balance and processes of a healthy rhizosphere.

Nutrients and Additives: The nutrients and additives used in organic gardening are comprised of natural ingredients and components, both to feed the food web, and the plant itself. Popular substances used are emulsified fish, seaweed, humic acid, humus, molasses, compost and/or compost tea, yucca extract, guano, earthworm castings, coffee grounds, bone meal, blood meal, alfalfa meal, greensand, dolomite lime, and the list goes on!

Beneficial Inoculants: There are many over-the-counter beneficial inoculants that an organic gardener can purchase to take the soil food web into their own hands. Many of these inoculants contain some mixture of mycorrhizae, beneficial bacteria, trichaderma, humates, and/or kelp (seaweed). The humates and kelp serve as an instant food source for the other living ingredients. Some popular brand names for such products include: Mykos, Plant Success, Piranha, Tarantula, and Orca. Another all natural inoculant is compost.

What is compost?

Compost is the quintessential representation of what happens in nature. Organic green scraps, coffee grounds, and fruit and vegetable scraps are decomposed using oxygen and water. Earthworms and mycorrhizae start to inhabit, and break down the organic material in an attempt to convert it to humus which is a food source. Healthy aerobic bacteria also facilitate the chemical changes of the organic matter by converting it into heat, CO2, and a form of ammonium. The ammoniums then are converted into nitrates that are usable to the plant. Compost typically contains nutrients (mostly nitrates), beneficial microorganisms, and humus. It can also work great as a soil conditioner in sandy soil, like we have here in Florida, by adding moisture retention, and increased nutrient uptake.

It is important to use well decomposed compost, as it will actually compete with the plant for nitrogen if it isn’t. Well decomposed compost is what gives extra nitrogen to the plant. The soil food web is well at work here! This is why compost tea is becoming increasingly

Compost: Key Organic Gardening Ingredient

What is compost tea?

Compost tea is an aerobic concentrate of beneficial microbes. It actually contains a denser population of the beneficial microbes than stand alone compost! At Urban Sunshine, we make compost tea weekly by adding compost, earthworm castings, and additives to feed the microbes to an actively aerated reservoir of water dechlorinated for at least 24 hours. After taking a sample out of the actively aerated environment, one has four hours to use the sample by either watering it into the soil, or foliar spraying it. If one can get the sample refrigerated within four hours it can remain aerobic for about a week. After that it must be disposed of. Compost tea can also be “cut” with water by up to a 1:5 (tea/water) ratio, although no bad effects have been observed in its pure form.

Other than a regular grow/bloom nutrient, what are some popular additives?

Vegetative and flowering additives can be in a liquid or granular form. Liquids have to be added more frequently, and added cumulatively, while slow-release granular fertilizers are added less often that many times contain traces of beneficial fungi and bacteria. Popular liquid or granular additives can help get the most out of your plant performance, and the soil food web:

Humic Acid: a byproduct of the decomposition of organic matter. It feeds the soil food web, and helps with the transportation of nutrients within the plant.

Kelp: typically Ascophyllum nodosum in the horticultural field, this is a very popular additive due to its myriad of benefits. Ascophyllum nodosum is a North Atlantic seaweed that grows almost a meter a day in just above freezing temperatures. This is facilitated through powerful growth hormones (auxin-like gibberellins and cytokinins). These hormones facilitate explosive growth and vitality. It also contains traces of nitrogen, phosphorous, potassium, calcium, magnesium, sulfur, zinc, and iron. It can almost be a fertilizer on its own!

Emulsified Fish/Squid: a cheap, water-soluble liquid that is high in available nitrogen. It also contains traces of phosphorous, potassium, and secondary/trace minerals. Plants need a ton of this to develop a toxicity, and the nutrient is immediately available to the plant.

Worm Castings: is “worm poop.” Castings contain digested humus and nitrogen-heavy decaying matter, along with many other trace elements. Worm castings should never exceed 1/5 of the total composition of the soil. Use 1 to 1 ½ cups of castings per plant should be enough to sustain them through vegetative growth. Take care to mix evenly into the soil.

Blood Meal: this is dried and ground blood that is recycled from slaughterhouses. It is mainly a nitrogen booster, and therefore, should be used in vegetative growth. It can be potent so try to add a little at a time to avoid a toxicity.

Bone Meal: is ground up cow bone that is collected from slaughterhouses. It is typically phosphorous heavy, and becomes more so the older the bone was at time of death. This is therefore more of a flowering additive. Bone meal can also contain lime, and therefore, could be a good amendment to soils with higher peat content to counteract the natural acidity.

Dolomite Lime: contains respectable amounts of calcium and magnesium, which are two very important secondary nutrients. The base pH of lime makes it a nice treatment for acidic soils too.

Coffee Grounds: if you make drip coffee you’re in luck! Coffee grounds are abundant in nitrogen, and trace elements. It is also very acidic. This can be used to treat base soil but be careful not to use to much. It also draws bacteria to the soil!

Greensand: is a great source for silica, iron, phosphorous, and potassium. Greensand can be very slow-releasing, so it’s better to treat soil or plants that will be utilized for quite some time.

Rock Phosphate: is another very slow-release fertilizer. It can contain up to 30% phosphorous, giving it its moniker.

Guano: the excrement of bats and seabirds from around the world. The rule usually is that the new guano is high nitrogen, while older guano is high phosphorous. As far as buying it goes, Mexican guano is high nitrogen, Peruvian guano is high nitrogen and phosphorus (all purpose), Jamaican is high phosphorous (bulking), and Indonesian is high phosphorous (ripening). Guano can be brewed in a tea and watered in, or applied as a slow-release top dressing.

Feather Meal: is good for compost piles, or as an additive. It is high in nitrogen, and releases slowly. Chicken manure may also be found in the mix. The feathers are taken from the slaughterhouse, steamed, dried out, and ground into a powder-like substance.

Stephen Brookes
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Stephen Brookes

Manager at NPK Technology
Much love to you, the readers of Garden Culture. You're my type of people because you are currently doing what I believe is the key to success; reading, and learning! I am privileged to be one of the GC writers and I find myself amongst some of the most knowledgeable growers in the hydroponics industry. Use their knowledge and decades of experience to inform and educate yourself to become the best grower you can be.

Myself in a nutshell - Science fanatic, hydroponics obsessed and book worm! Bachelor of Science in Outdoor Education and Geography, MSc in nutrition and scientific investigation, commence Ph.D. in October 2017, researching the effect of different ratios of cannabinoids in the human body.
Motto: The more you learn, the less you know!
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