---- "Chalfant wrote: > Greetings all - > > I'm interested in people's persuasions on the wisdom of crushing up mollusk > shells found in a local river (the Susquehanna near Harrisburg, Pennsylvania > to be specific) and use the crushings as a soil amendment in food > garden/farm. Great natural source of calcium and carbonate for crops that > like less acidic soils and need calcium for strong bones, right? ; ) I'd > particularly like to know if there is any reason to be concerned about > contaminants being incorporated into the shells and thence into the plants... > this seems intuitively unlikely to me, but I'd like to get some other > opinions on this practice since I intend to eat, sell, and share the food > grown in said soil. Thank you kindly.
Hi Brian, I've just finished reading David R. Montomery's fascinating history of agriculture and soil degradation, _Dirt, the erosion of Civilizations_ (University of California Press 2007). From Montgomery, I learned that the ancient Greeks, Romans, and other agriculturists of their time used crushed mollusk shells as soil amendments, to correct acidity and provide nutrients. The practice is longstanding, and if you think about it, the modern practice of adding limestone, whether processed or not, is simply drawing from a more ancient time for the material, but it is essentially the same stuff. Now, so far as contaminants -- you might want to be sure of your source, and to read up on uptake of heavy metals into plant tissues. I know nothing about it. I do know that mollusk shells serve as an index to the presence of such metals in the environment where they occur, and that we are cautioned about lead in soils, for example from paint peeling from barns and other structures. david mcneely
