Deleterious Effects of Seaweed as a Soil Amendment

Submitted by Robert D . Lucas, Ph. D, CFS, Certified Food Scientist

Recently, there has been a hue and cry over the use of Sargassum seaweed as a soil amendment locally. Mr. Joshua Forte has been touting the benefits to be derived  from the use of the fertilizer. On the other hand, Ms. Deborah Hunte, President of the Farmers’ Association of Barbados, has aired her reservations about the use of the fertilizer. Ms. Hunte is on safe grounds scientifically as I will show.

Anyone who has been trained in agricultural sciences (specifically in soil science) would be aghast at the ignorance displayed locally. The deleterious effects which have been described by Ms. Hunte in St. Lucy, can be attributed to the development over time of soils that are called saline-sodic.  In the case of saline soils, the difference in the osmotic pressure between soluble salts in the soil solution and added salts derived from the seaweed, results in the formation of saline soils which affect plant growth over a period of time. Eventually, the salt content of the added fertilizers becomes greater than the salt content of the soil solution; as a result, there is a flow of water from the soil solution towards the fertilizer. This results in the salt content of the soil solution becoming more concentrated. In addition there is  transpiration of water by the plant: this water is adsorbed by the plant roots from the soil solution: and there is also the action of solar evaporation of water from the soil solution. These two factors which are called evapo-transpiration result in an increase in soil salinity as well. If the saline content is  high enough it can negatively affect plant growth, resulting in reduced crop yields and even plant death under severe conditions.

In the case of sodic soils, a feature known as the  cation exchange capacity(CEC) of the soil comes into play. This feature is best explain in terms of surface chemistry and the mono-layer adsorption (adsorption not absorption) on a surface. Soil particles and soil organic matter are negatively charged. The metallic radicals of dissolved salts in the soil solution are positively charged and are adsorbed onto the negatively charged soil particles mentioned above. Adsorption is directly proportional to the size of the charge on the metallic radical and its ionic radius/volume. For example  calcium sulfate CaSO4  = Ca ++ + SO4– –. (Ca++ is the metallic radical). Ca ++  is adsorbed before a sodium Na+. since it has a charge of plus two, whereas, sodium has a charge of plus one. Calcium also has a greater ionic volume. However,  if  large concentrations of sodium salts are added to the soil, sodium is then adsorbed onto the surface of soil particles. If fifteen percent or more  of the CEC of a soil has adsorbed sodium, the soil a sodic one. Soil sodicity causes degradation of soil structure which results in soils difficult to till, poor seed germination and restricted plant root growth.

Digressing, recently Morocco donated one million dollars for the Ministry of Agriculture to carry out a survey of soil fertility in Barbados. Vernon, K.C and Carroll, D.M (1965) “Soil and Land Use Surveys # 18, Barbados,” Imperial College of Tropical Agriculture  (ICTA) have done detail surveys of soils of Barbados and the other  Caribbean Islands. The fertility of the soils and the land use patterns to be adopted for Barbadian soils have been documented by Vernon and Carroll. It seems that The Ministry wants to re-invent the wheel.

33 comments

  • Well Well & Cut N' Paste At Your Service

    I would imagine that there will be agriculturalists with the knowledge, skills and practiced know how to extract the saline sea salt content from the seaweed, apparently there are those who have already done this before processing the plant for agricultural useage.

    Liked by 1 person

  • Dr. Lucas what should also be if concern to you is that govt has taken upon itself to pump sewage into the Graeme Hall swamp as a quick fix for the ongoing problem at the Sewage plant
    Dr. Lucas this is a matter which can do dangerous harm to plant and animal life not to mention the numerous problems which result because of toxins and bacteria entering the water system underground and from which households use as a source for daily mainteance.
    This problem is serious and should be of grave concern

    Like

  • Georgie Porgie

    this should be great fun!
    the BU BRIMBLERS WITH TOTAL IGNORANCE OF WHAT IS BEING SAID WILL BRAY WITH GUSTO FROM PORT TO STABORD ah lie?
    um start already murdah

    Liked by 1 person

  • Good Post until the doctor to threw in a few formulae… That was the Bajan influence
    Wuhloss… they gun kill you Theo… you threw a flame at a sacred cow.
    Still a good post
    Added reading:
    http://waterquality.montana.edu/energy/cbm/background/soil-prop.html

    Liked by 1 person

  • A hearty good morning to all the beautiful people in Barbados, and a equally hearty good morning to those who are not beautiful.
    before I get serious let me ask the following.
    Could it be possible that though Bajans claims African ancestry our true roots are in India.
    We have scared cows
    We have a rigid caste system, and
    we have scared ideas about technology
    A great morning to all. 🙂

    Liked by 1 person

  • 🙂 auto-correct idiocy 🙂
    We have sacred cows
    We have a rigid caste system, and
    we have sacred ideas about technology
    A great morning to all. 🙂

    Like

  • As usual bajans would run around with head cut off looking for quick fixes
    Barbados have now entered an era of headless govt and ignorant mutterings coming out of the mouth of those the people have elected.. now resulting with barbados having ministers touting magical solutions to all of barbados problems
    What a dam sham

    Like

  • We have sacred cows
    We have a rigid caste system, and
    we have sacred ideas about technology

    @TheoGazerts

    I never looked at the issue from a religious filter. Perhaps we are Hindu more than Christian after all. That may explain so may traditions and their associated demi-god status.

    From another perspective i think it is because we spend to much of our time in sitting in the dump of a dump truck. Usually their is a driver of the dump truck he is the lucky one he see the road up ahead and sees what is coming and controls the vehicle as such. Additionally the driver sits in the cab; is surrounded by all the feedback gauges, knows how the vehicle is performing..Also the driver gets to sit in relative comfort in the weatherproof cab.

    The persons riding in the back only sees the past; can only look backwards; the dump is not weatherproof we get to endure the elements. We as bajans are so accustomed to the back of the dump truck that we are opposed to sitting in the cab so we can see the road ahead. We spend so much time looking back and justifying current evils solely based on the past that we do not engender ourselves to be future drivers.

    Let us not forget that the driver also has the privilege is tipping the dump and discarding the occupants when he so desires. we need to embrace the future ans sacrifice some of our sacred cows etc. Repent and become the Christian nation we so proudly claim to be.

    jmt

    Like

  • A timely intervention by Dr.Lucas I especially liked “aghast at the ignorance displayed locally” hopefully that will tamper the enthuiasm of the local pols who were anxious about the prospect of a new agro supplement.
    All is not lost , there is always a sea weed concoction to charge up the libido of the flagging politicians who now have more money than sense.

    Like

  • Bernard Codrington

    @ Theogazerts at 8:08 AM

    Some how ,I prefer the “scared cows”.

    @ Dr Lucas.

    Erudite submission as usual. Can you tell us what were the main findings of the 1965 study on the soil fertility of Barbados ? And has there been any recent follow-up studies on soil fertility ?

    Like

  • A Tropical Storm Watch is in effect for…
    * Barbados

    Like

  • CAN WE GET BACK TO DISCUSSING DR LUCAS’S ARTICLE PLEASE…………if at all possible. lol murdah

    Liked by 1 person

  • I agree with theo about the india connection..it seems barbados is always sikhing reparations or something from sombody

    Liked by 1 person

  • Georgie Porgie

    I ain’t letting you laff at me. I ain’t know nuh chemistry but I know Dr Lucas well and once it got to do wid chemistry, Dr Lucas is in his element (no pun intended).

    Liked by 1 person

  • Andrew Simpson

    Posted on BU’s FB page. The blogmaster is aware Andrew is experimenting with the % of mix required to optimize plant growth.

    We are just setting up some new research which aims to evaluate the response of seven crops, in up to ten various growing media, many containing sargassum (at different stages of decomposition) including Red Diamond organic concentrate. Help wanted.

    Like

  • RE Ping Pong July 7, 2018 11:28 AM

    Georgie Porgie

    I ain’t letting you laff at me. I ain’t know nuh chemistry but I know Dr Lucas well and once it got to do wid chemistry, Dr Lucas is in his element (no pun intended).

    I DONT KNOW DR LUCAS, BUT I CAN TELL HE IS IN HIS ELEMENT WITH CHEMISTRY
    VERY GOOD PUN SIR…..EVEN IF NOT INTENDED

    Like

  • put it in your concrete instead

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  • PoorPeacefulandPolite

    Landfill !!

    Like

  • Are-we-there-yet

    re. David’s post of 12:09 pm

    Andrew; What kind of help do you want?

    Like

  • Very good article.Thank you.I gather Dr Lucas is saying the plants would die of dehydration.

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  • I do a little farming and I would be sceptical about using sargassum, unless the salt was removed. I’d be worried about salting my soil, and I would worry about how to get rid of the salt if it turns out to be very bad for the soil and the plants. Maybe if it is washed and composted it would be safe to use?

    On the other hand since constantly being bathed by salt sea air, so presumably our soils are already quite salty.

    Like

  • @lawson July 7, 2018 1:21 PM “put it in your concrete instead.”

    Don’t mind lawson. He is being mischievous at best or malicious at worse.

    Do NOT, repeat NOT add a salty substance to your concrete.

    Like

  • Instead of pontificating and espousing high science for ego satisfaction. What we need are solutions, so instead of saying it CAN’T successfully be used. Let’s figure out where it CAN successfully be used and let’s get at it. Forget the ego massaging and let’s get to work

    Like

  • Now if only someone can find a way to make it into seamoss drinks, long a favourite of bajan men, as a home treatment for erectile dysfunction, although we know of course that no Bajan man has ever had erectile dysfunction.

    If we can turn the seaweed into something better and tastier and cheaper than Viagra or Cialis, then we gone clear.

    Like

  • So far we have found sargassum to be beneficial. Carrying out a series of trials now to evaluate further. Anyone wishing to take part please contact care@caribsurf.com.

    Like

  • Check out the video by permaculturalist Geoff Lawton called “Greening the Desert” (link below). He describes how barren, salted land (from over irrigation) in the nation of Jordan in the Middle East was revived using permaculture (organic) growing techniques to overcome the excessive salt burden in the soil in order to make the soil productive for growing fruit again. It is notable that all the local Jordanian experts educated in modern, agricultural techniques had given this project no chance for success, until Lawton showed them to be wrong.

    Lawton’s techniques included capturing and storing as much as possible of the minimal winter rainfall in swales (i.e. shallow trenches dug on contour), laying down thick layers of organic matter (imported from off site, as the land itself was now barren) as mulch and compost to help the moisture in the soil, and the planned, staged planting of various trees and plants appropriate to the local soil/climatic conditions as the soil gradually recovered.

    See the first 5 minutes or so of “Greening the Desert” for an explanation of how the salt burden was neutralized without needing massive quantities of fresh water to flush the salt out of the soil: https://youtu.be/2xcZS7arcgk

    FYI: We have our own, local permaculture project ongoing in St. Andrew at Walker’s Reserve. This site to the East of St. Andrew’s Church has been used as a sand quarry to mine building sand for a period of approximately 50 years, and much of the area has now been mined out. The land owners have started using permaculture techniques similar to the ones described in “Greening the Desert” to restore the top soil in the mined out area. As the mining operations shut down, most of the land consisted of a surface layer of sand incapable of growing much more than sea grapes or coconuts. The land is now being turned into a fertile soil suitable for supporting a “food forest” of various varieties of fruit trees, coconuts, cashews etc. I have heard that they have harvested seaweed from the local beach and applied it to the land as part of their restoration process.

    See the Walker’s Reserve web site at http://walkersreserve.com or look up Walker’s Reserve Barbados in Facebook.

    Liked by 1 person

  • GreenMonkey July 8, 2018 4:56 PM

    Thanks for the link to Walkers Reserve.

    Like

  • THE STUDY BELOW WAS UNDERTAKEN IN 2003. Praedial larceny has a huge impact on farmers ability to farm successfully

    http://unctad.org/en/Docs/ditctncd20031p2_en.pdf

    Liked by 1 person

  • pieceuhderockyeahright

    As usual de ole man will “go south” because “two roads diverged in a shady growth…and to be one traveller long I stood and took one path as far as I could to where it bent in the undergrowth…”

    There are two schools of thought here namely that sargassum s the Saladin of fertilizers (and may even be the cure for erectile dysfunction and the DLP waste foops) and the other that it is “deleterious” to the soil

    Dr ole man shall take that “deleterious to the soil” avenue but for a few moments more to a not so natural progression.

    My question to Andrew Simpson or the Dr. Lucas who wrote this is

    You said and I quote “…poor seed germination and restricted plant root growth….”.

    In that vein given that we have an abundance of Bush on abandoned properties as well as in the byeways and abutments across the length and breadth of our roads and highways could a variant be developed that would be designed specifically for the purpose of killing the bush in these localities?

    De ole man is not a certified food specialist like you but if you were to add the effluent of shells and decimposed bodies of the infestation of giant snails to this mix it kills all the grass that is growing in the area that you pour it on.

    Do forgive my myopic queries and attribute such rambling talk to my membership of the BU clan that “opposes for opposing sake!”

    Like

  • pieceuhderockyeahright

    @the Honourable Blogmaster your assistance please with a recent submission thank you

    Like

  • INTERESTING THOUGHTS AT 11:24 AM PIECE
    WORTHY OF TESTING
    NOT BAD FOR A MYOPE WITH membership of the BU clan that “opposes for opposing sake!”

    Like

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