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questions about collecting seagrass and seaweed for soil building

 
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Along the shorelines, I often find turtle grass washed up; if a storm system churns up the ocean over the Sargasso Sea, I tend to find piles of sargassum weed two or three days afterward.

Now, in theory, every rainy season, our soils lose minerals to the sea, right? Rains dissolve soil minerals and wash them out. The rivers on the North Coast are very flashy, i.e. they become raging torrents after rain, and during those times, are generally the color of a latte, from the suspended sediments. So bringing marine vegetation back up to the ridge top should help to restore the soil minerals, if done on a large enough scale. My worry was that this might expose the plants to too much salt; but on the small scale I have been able to experiment with this, I find no evidence of damage.

I do wonder whether the turtle grass, from inshore waters, has a different trace mineral content than the sargassum, from far out at sea? More importantly, I wonder how much of this marine vegetation I need to make a difference in soil mineral content, and how much is too much? I really don't know any way of testing this.
 
pollinator
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Dr Bryant Redhawk has some excellent info in the soil forum regarding seaweed and seawater.
 
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If you think of minerals as existing on a supply chain, the beginning of that supply chain is volcanic activity. Molten rock is sprewed from underground, and is broken down by erosion, wind, water, digestion enzymes, over and over, through several trophic levels, transported over the landscape until it eventually ends up in our waterways at the end of the supply chain, the ocean.  

That's why garden stores carry products like volcanic rock dust, or kelp meal. These products contain the "full spectrum" of minerals.  

Adding seaweed and seawater (properly diluted) to your soil is a great way to remineralize it.  In addition to the geology, you also need the biology to process these mineral into plant-available forms.  You can think of your soil microorganisms as supertiny crawling bags of nutrients. A healthy soil food web will contain the minerals as well as the means to transfer them from organism to organism, so things are not washed away in a heavy rain event, or sitting inert with no possibility of uptake.
 
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I will just say that most commercial chemical fertilizers will have a much higher salt content than the seaweed you speak of. That being said, a simple freshwater rinse would probably remove any salt, but may also remove those valuable minerals lost to erosion. My general rule of thumb is to only apply diluted seawater to my garden twice a month, so I would think you will be fine to add this.
 
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Location: Vilonia, Arkansas - Zone 7B/8A stoney, sandy loam soil pH 6.5
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Jason Hernandez wrote:Along the shorelines, I often find turtle grass washed up; if a storm system churns up the ocean over the Sargasso Sea, I tend to find piles of sargassum weed two or three days afterward.

Now, in theory, every rainy season, our soils lose minerals to the sea, right? Rains dissolve soil minerals and wash them out. The rivers on the North Coast are very flashy, i.e. they become raging torrents after rain, and during those times, are generally the color of a latte, from the suspended sediments. So bringing marine vegetation back up to the ridge top should help to restore the soil minerals, if done on a large enough scale. My worry was that this might expose the plants to too much salt; but on the small scale I have been able to experiment with this, I find no evidence of damage.

I do wonder whether the turtle grass, from inshore waters, has a different trace mineral content than the sargassum, from far out at sea? More importantly, I wonder how much of this marine vegetation I need to make a difference in soil mineral content, and how much is too much? I really don't know any way of testing this.



Land minerals tend to be limited to around 75 different minerals, these can be tested for chemically and have been identified by those processes.
Sea water usually has around 95 minerals, so sea water has 20 minerals not found in soil that is on dry land.

Now that we know that there are differences between sea minerals and land minerals, it should be easy to see that fresh water items would not have the same mineral makeup since fresh water would be missing at least 20 minerals found only in sea water and sea plants.

As long as you are not doing anything to concentrate the sea weeds, it would be very difficult to over use the marine vegetation, and you don't need to rinse it off, in fact, it is better to not rinse sea weeds prior to use on land plants.
Contrary to what most seem to believe, sea salts do not "salt up' the land, you can flood land with sea water, this is actually done in several countries to get the soil re-mineralized for planting.
Studies have been done and we know you can put 28000 gallons of sea water on one acre of land with no ill effects to the microbiome, which means the plants in that soil will do fine as well.

Redhawk
 
pollinator
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Fascinating! Could I take the raw sea salt here in Haiti and rehydrate it and use it instead of seawater? It should contain the minerals, right? Perhaps add a handful to compost tea before diluting?
 
Bryant RedHawk
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That would be very close to ideal Priscilla.

Sea salt can be used as a solid or as a solution, doesn't really matter to the plants if they are watered with it or if it slowly leaches into the soil.

Redhawk
 
Priscilla Stilwell
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Bryant RedHawk wrote:That would be very close to ideal Priscilla.

Sea salt can be used as a solid or as a solution, doesn't really matter to the plants if they are watered with it or if it slowly leaches into the soil.

Redhawk



Does that have the danger of burning the plants to sprinkle it on as a solid?
 
Bryant RedHawk
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No, you want to put it at the outer ring of roots (drip zone) but since that is hard to figure out with the palms, I'd make sure it was at least 8 inches from the trunk.
You want to sprinkle it around, not end up with a pile. I use sea-90, a non-purified sea salt from the sea of cortez and I put it around all my trees at the start of each season, since all my trees are apple, pear, peach, mulberry and plum, I have an easy drip line to follow.
If you looked around any of my trees you would think I just sprinkled salt on a batch of French fries, it is that thinly applied.

If you use the sea salt to make "sea water" just water in with a gallon per tree, all around the tree is how you want to use it.
You can apply sea water at a rate of something like 1 gallon per square foot with no issues.
Sea Salt is not even close to "table salt" (NaCl), many of the salts in sea salt are going to be non chloride salts.
Which means less chance of nasty things happening to your soil, the salinity doesn't go up much if at all with the small amounts we want to use for plant health and food flavor.

Redhawk
 
Priscilla Stilwell
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Bryant RedHawk wrote:No, you want to put it at the outer ring of roots (drip zone) but since that is hard to figure out with the palms, I'd make sure it was at least 8 inches from the trunk.
You want to sprinkle it around, not end up with a pile. I use sea-90, a non-purified sea salt from the sea of cortez and I put it around all my trees at the start of each season, since all my trees are apple, pear, peach, mulberry and plum, I have an easy drip line to follow.
If you looked around any of my trees you would think I just sprinkled salt on a batch of French fries, it is that thinly applied.

If you use the sea salt to make "sea water" just water in with a gallon per tree, all around the tree is how you want to use it.
You can apply sea water at a rate of something like 1 gallon per square foot with no issues.
Sea Salt is not even close to "table salt" (NaCl), many of the salts in sea salt are going to be non chloride salts.
Which means less chance of nasty things happening to your soil, the salinity doesn't go up much if at all with the small amounts we want to use for plant health and food flavor.

Redhawk



So you're talking about trees in general. I have a bunch of newly planted baby trees that I'm trenching starting about 8 inches or so from the trunk, out about 18 inches all around, and using that to dump a bunch of organic material, manure, and other goodies. Would it benefit them? I have:
Starfruit
Almond
Pomegranate
Maylay Apple
Peanut Butter Fruit Tree
Breadfruit
Mulberry
Peach Palm
Egg Fruit
Black Sapote
Ackee
Sapodilla
Velvet Apple
Jackfruit
Mango

Haven't gotten them all trenched yet, but if it can help, might as well give the extra boost!
 
Bryant RedHawk
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We are talking about adding minerals that are not found in any soils, anywhere on the planet, so yes the minerals in sea salts are going to be good for any tree and for any vegetable crop as well, it will increase the flavonoids in all fruits and vegetables and who doesn't want more flavor from their foods?
Oh and it also increases the nutritional values for them all too, which makes you healthier and better able to fend off any illness or disease.

Redhawk
 
Priscilla Stilwell
pollinator
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Bryant RedHawk wrote:We are talking about adding minerals that are not found in any soils, anywhere on the planet, so yes the minerals in sea salts are going to be good for any tree and for any vegetable crop as well, it will increase the flavonoids in all fruits and vegetables and who doesn't want more flavor from their foods?
Oh and it also increases the nutritional values for them all too, which makes you healthier and better able to fend off any illness or disease.

Redhawk



Cool. I'll give it a try.
 
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The 1930’s Irish documentary “Man of Aran” is worth a watch for the scenes of gathering seaweed and piling it up on flat areas of the rocks to create soil. The film is controversial from a documentarian viewpoint for recreations by the filmmaker, but I believe those controversies don’t extend to the traditional practice of soil building, or more appropriately rebuilding. The early inhabitants practice of cutting down the trees for building and fuel caused the loss of the islands fertile soil So to survive they had to resort to grueling work to rebuild soil to grow food on.

The film can be watched here and the segment on the collection of seaweed and soil from crevices to create soil beds starts around 14 min 30 seconds in and runs about 10 minutes (the film is an hour and 13 minutes and well worth watching).

Here is a brief story on a traditional farmer on Aran today with some very pretty pictures.
 
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