Could Kelp extracts be a waste of money?

[Thcdomemommy]

Perhaps my good results from kelp are not actually due to the foliar application of kelp? I think it's time to do a controlled experiment this flower round to get to the bottom of kelp effectiveness.

 

[goingrey]

I think it's quite well studied...

From Plant biostimulants: Definition, concept, main categories and
regulation by Patrick du Jardin (fitting name):

The use of fresh seaweeds as source of organic matter and as fertiliser is ancient in agriculture, but biostimulant effects have been recorded only recently. This prompts the commercial use of seaweed extracts and of purified compounds, which include the polysaccharides laminarin, alginates and carrageenans and their breakdown products. Other constituents contributing to the plant growth promotion include micro- and macronutrients, sterols, Ncontaining compounds like betaines, and hormones (Craigie, 2011; Khan et al., 2009). Several ofthese compounds are indeed unique to their algal source, explaining the increasing interest ofthe scientific community and of the industry for these taxonomic groups. Most of the algal species belong to the phylum of brown algae – with Ascophyllum, Fucus, Laminaria as main genera-, but carrageenans originate from red seaweeds, which correspond to a distinct phylogenetic line. Product names of more thant 20 seaweed products used as plant growth biostimulant have been listed by Khan et al. (2009).
Seaweeds act on soils and on plants (Craigie et al., 2008; Craigie, 2011; Khan et al., 2009). They can be applied on soils, in hydroponic solutions or as foliar treatments. In soils,their polysaccharides contribute to gel formation, water retention and soil aeration. The polyanionic compounds contribute to the fixation and exchange of cations, which is also of interestfor the fixation of heavy metals and for soil remediation. Positive effects via the soil microflora are also described, with the promotion of plant growth-promoting bacteria and pathogen antagonists in suppressive soils. In plants, nutritional effects via the provision and micro- and macronutrients indicate that they act as fertilisers, beside their other roles. Impacts on seed germination, plant establishment and on further growth and development is associated with hormonal effects, which is viewed as major causes of biostimulation activity on crop plants. Although cytokinins, auxins, abscisic acid, gibberellins and other classes of hormone-like compounds, like sterols and polyamines, have been identified in seaweed extracts by bioassays and by immunological tools (Craigie, 2011), there is evidence that the hormonal effects of extracts of the brown seaweed Ascophyllum nodosum are explained to a large extent by the down- and upregulation of hormone biosynthetic genes in plant tissues, and to a lesser extent to the hormonal contents ofthe seaweed extracts themselves (Wally et al., 2013a,b). Molecular genetics, i.e. hormone mutants in Arabidopsis and transcript analysis by RT-qPCR, were used to reach this conclusion.
Anti-stress effects are also reported and both protective compounds within the seaweed extracts, like antioxidants, and regulators of endogenous stress-responsive genes could be involved (Calvo et al., 2014).

One thing that I wonder about though is all the heavy metals and other poisons we have dumped in our oceans. Does that come with the package?

 

[chilliwilli]

One thing that I wonder about though is all the heavy metals and other poisons we have dumped in our oceans. Does that come with the package?

Yes it can accumulate heavy metals.
https://www.sciencedirect.com/science/article/abs/pii/0143147180900938
https://www.webmd.com/vitamins/ai/ingredientmono-1566/ascophyllum-nodosum

And the extract can also improve uptake of heavy metals from soil in other plants(because they produce more biomass)
https://www.researchgate.net/public...ion_of_Cadmium_and_Lead_in_Contaminated_Soils

 

[xtsho]

Yes they're a waste of money. If you want to use kelp as a foliar just get 5 lbs of kelp meal for $15. Mix 1/2 cup with 1 cup of water and let sit for an hour. Then puree into a paste. Use 2 tsp per gallon for foliar. Store the rest in a well sealed container in the refrigerator until you need to make more.

I think I have a small jar that's been in the back of my refrigerator for a couple years that I need to toss out. I wasn't noticing any difference with the kelp foliar so I stopped bothering. I bought a 40 lb bag of kelp meal for around $50 years ago to use outdoors in my vegetable garden and I still have about 20 pounds left. I reuse my soil so when I amend it I add a little kelp.

I only foliar for IPM. Pests, PM, Mold, etc... If you want to use kelp it's just easier to mix some into the soil.