Dr. Lucas Responds to Peter Webster’s Deleterious Effect of Seaweed on Soils Piece
Submitted by Robert D. Lucas, Ph.D. and CFS, Certified Food Scientist
There was an article in the Nation of 26th July entitled “How to handle sargassum” by Mr. Peter Webster. Webster in paragraph one seems to have a problem with “however, if large concentrations of sodium salts are added to the soil.’In paragraph two he cites some work done in Portugal that indicates sargassum “has a strong potential as functional food ingredient.” These comments of Webster are now dealt with.
All sodium salts are soluble and there is therefore a tendency for these salts to be leached downward. In periods of drought, sodium salts rise by capillary action to the surface of the soil. It ought to be obvious that with the repeated addition of seaweed to the soil, there will be an accumulation of sodium in the soil profile; that under dry conditions can rise by capillary action and affect both the salinity and sodic nature of the soil. Is Webster suggesting that the sargassum is only going to be applied once to the soil? Webster conveniently ignored the fact that in paragraph two of my article it is stated “the deleterious effects described by Hunte…can be attributed to the ..development over time of soils that are saline-sodic.” Webster makes an issue of the ratio of potassium (K) to sodium (Na) in the living seaweed In any event K:Na in the living seaweed has nothing to do with what happens when seaweeds are decomposed by microbial action in the soil. As previously stated, since K has a greater ionic volume/radii than Na, it is adsorbed before Na.
I have addressed the uses of seaweeds in food in my article of 14th July in your on-line paper.
Robert D. Lucas,Ph.D. and CFS.
Certified Food Scientist.