Kelp Fertilizers and Soil Amendments in Organic Gardening

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If you’re an organic gardener you have probably seen and used kelp products. They come in a variety of forms from liquid fertilizers to dried kelp meal and powders. So with all of these products out there what benefit do they bring to your garden and are they worth it? Lets start with taking a look at what benefits Kelp brings to the garden table. Nitrogen Phosphorus and Potassium are some of the macro nutrients required for plant growth and because they are used in such high quantities are often the nutrients that get depleted in the soil the fastest. The highest reported Kelp product NPK was Kelp powder. The Colorado State Extensions website reports the NPK at 1 – 0 – 4. [5] A variety of sources state the NPK of the other product as negligible. Often kelp products are mixed with fish products to give them an NPK. With a low or negligible NPK let’s take a look at the trace elements in Kelp products. There are generally speaking 18 elements in the soil that are considered to be essential or beneficial to plant growth.[8] The presence or absence of these elements will impact the overall plant growth and production. Of these 18 elements it is common to test for all but Chlorine and Silicon as they are well distributed on earth. Many species have been used for agricultural purposes as to add essential and beneficial elements. One such species of Kelp was analyzed for trace elements Stoechospermum marginatum. The results are in mg/L and included Copper, Manganese, Zinc, Iron, Potassium, Magnesium, Cobalt, and Sodium. [2] These account for 8 of the 16 essential and beneficial elements required for plant growth that are commonly tested for. Kelp is commonly marketed not only to add elements to the soil but as having plant growth hormones. Plant growth hormone can have a number of benefits to vigor and growth in your garden. Most notably is its ability to stimulate root growth. [6] Larger root systems anecdotally result in healthier plants that can resist disease and stress better while producing larger harvests. Kelp has been found to have high concentrations of plant growth hormone [2]. The hormones found in kelp extracts have been shown to have varying success in aiding the establishment of seedlings and any net gain is lost in the first 5-10 weeks of growth. [6] Over application of the concentrated hormones was also shown to have a net negative effect on seedlings growth. Kelp products seem to bring some benefit for our gardens. Right? Well I am not sold on the idea of using kelp products in my garden. Let me explain why. The two main benefits kelp brings to the garden is essential and beneficial elements and plant growth hormones. Over the last few weeks we have evaluated a number of free and local resources. Specifically fall leaves and comfrey. Both have been shown to have essential and beneficial elements. Fall leaves have 11/16 essential and beneficial elements while comfrey has 15/16. The one element that is missing form all three materials is selenium. As selenium is an essential part of at least 3 amino acids one can assume it is in any soils that have been amended with compost and it is simply below the tests detection limit.[9] So not only does comfrey have a good NPK in this case fall leaves and comfrey have more trace elements then Kelp does. So what about those plant hormones ? Earth worms and composting worms provide a number of benefits in your garden. They break down organic material releasing nutrients, beneficial bacteria and plant growth hormones. These rich castings can be made in worm farms or directly in the garden by letting them break down your mulch layer made of things like fall leaves and comfrey among others. A research paper published in the European Journal of Soil Biology found the same plant growth hormones found in the kelp extracts were also found associated with the humic acid in vermicomposts.[7] So once again a free and local resource has a source of plant growth hormones. A full transcript including references can be found: http://www.albertaurbangarden.ca/2015/02/28/kelp-fertilizers-and-soil-amendments-in-organic-gardening/

Comments

Awesome explanation thank you very much!!
What do you recommend Kelp Meal, Powder Extract or Liquid? What's the purest form?
Thanks

Seaweed and kelp soil amendments are marketed brilliantly and its subsequent popularity is massive. I think you have made many good arguments. I work in horticulture and have many private clients who do or have used these products for years. I have seen no benefit with its application. The same plant nutritional deficiencies and health problems appear to exist with or without their application and I therefore cannot justify the extra cost. In my experience people use it like they would asprin thinking it is some silver bullet and a cure all. Vermicompost, compost, covercrops, green manures,mulches and the micro flora and fauna they produce/support, are by far, more effective garden amendments.

I've been giving some thought into saving eurassian watermilfoil for the compost bin when it gets snagged on my fishing line. Not only is it a free and local resource, but it's also an invasive species so it's not damaging the ecosystem to take out of the water. I would imagine it adds a benefit similar to kelp.

Kelp is free and local to me. I don't use it as primary source but I have a much bigger amount of compost to generate than your backyard garden. Anything that helps is good to me, and everything in moderation is usually best IMO. Thanks for sharing. Your channel is an interesting contrast to most of the gardening channels here.

north Atlantic kelp vs pacific kelp found off BC..did you separate and test those?

Is this a channel where you "debunk" everything gardeners have been doing/using for years and years and years? I'm confused as you don't suggest anything beneficial or alternative. You buy a 1.5lpm air pump and try to make AACT, which is laughable - I'm not saying it does or doesn't work, and not just based on that air pump, I'm just saying that just made me laugh.
I've come across several channels today saying "compost tea doesn't work" and "kelp doesn't work". They then say "where's the studies, university this, university that". Where are the studies saying it doesn't work? And what does work mean? When your own evaluation of if it "worked" is literally looking at the plant with the naked eye and saying "it doesn't look any bigger"...any bigger?? Are you joking? Where's your scientific evidence then? Brix level? Pathogen, pest, and disease resistence? Extreme environmental change tolerance? Cell wall thickness or flexibility/resilience of the plants structure? Root system health? Terpenes, flavinoids (flavors and smells)? Essential oils (if applicable)? The list goes on.
I appreciate ANYtime someone goes through the trouble of trying to do one such a test or experiment - THANK YOU big time, all of you, for doing this. I too would love to throw out the idea, for example, of brewing this or that, or using this or that.
What is your end goal here? What is your overall suspision? What are you suggesting gardeners, organic or not, DO USE?
You're flippin my world upside down - lol.

Thank you sir.

love my comfrey!

Steve, you are always teaching me new stuff.. Thank you again, as you have again saved me money, as I was going to go purchase kelp. I have lots of !eaves around me, I really enjoy your knowledge, and thank God, we gardeners have you Sincerely long winded Rick😆

The question I have is how good is seaweed when added to compost. For people like myself we have access to seaweed in large quantities that are as you say "free and local" I'm less than 2 miles from a beach with large quantities of seaweed. I'm having a really hard time finding information on how to put this "free and local" resource to work for me. I've started doing experiments with composting and using it as a mulch but I'm hoping to find some information on uses of seaweed.

"If your" Correction "if you're" Repeat offence! Don't blame your iPod again :-) Leaving the matter of correct English aside, this was an interesting episode. I was unaware that kelp has little to recommend it. I used to live at the seaside and after a storm would collect seaweed by the wheelbarrow load. Now I know better.

I'm really enjoying your videos. Thank you for taking the time and being pleasant

Is Kelp high in sodium ?
It seems my papaya plants do not like it, or i used too much.
the kelp i used was made for human consumption, so maybe its different ?
it tasted salty.

ive used spirulina instead to good effect.
spirulina is often grown in lakes of fresh water
it is a darker green than kelp, and i think may be higher in mineral content.

Thanks Mr. Calgary, I'm new to gardening and you are helping me to avoid buying stupid stuff! Leaves! Leaves! Leaves!

Like your videos, very useful information. what I would like to know is do you know the best way to make a diy seaweed fertilizer. A way to keep most if not all the beneficial properties.. That would make for a awesome video.

in un-potted gardens you're proly correct.

Kelp is great for potted plants.

I am doing good .Hope all is well with you. My Garden is doing great .All i am using is wood chips And leaves .For the past 3 years I add wood chips and leaves each year. I all so use compost tea. And I only use rain water. I never dig in my Soil. I keep it simple.

You have just become my favorite person ever . Yes! , using organic and local products pay off in the long run and most of hthe times they are close to nothing in costs or even FREE ...! Yes! Peeps for FREE!

i live on the ocean and there is an abundance of bubble kelp, since its free and only infront of my house i was wondering how you would use it in your garden as a raw source? ive added it bit by bit to my worm bins but wasnt to sure on how to actually use the raw kelp in the garden

So can you use comfrey mill in a compost tea?

Awesome and informative video. You saved me a lot of reading. I recently purchased a 4lb bag of kelp for $17 plus tax I've been believing the hype and now am glad to have been enlightened..