What is copper sulphate used for in farming?

Hi all.

I remember from school that when copper sulphate is exposed to water, a chemical reaction occurs and heat is released. That got me to wondering if this simple fact could be used in some way to protect tender plants from frost, but of course chucking it on the ground or on the plants directly would be a very bad idea.

Then while having a search about, I found a farming supplies shop that sells big tubs of copper sulphate. I know it is one of those chemicals that must be handled with great care, so I just wondered what it would be used for on a farm.

Incidentally, I don't really need to know, as I probably won't be doing any experiments with it, but was just curious.

 

Only use I know of, is as a fungicide

 

I think that the quantity of heat released when copper sulphate crystals are mixed with water would be so small that it wouldn't help to protect tender plants.

I would agree with Pete - it is used extensively as a fungicide. Salts of copper and silver ( and probably some others) can kill bacteria. Copper sulphate and ammonium carbonate are the ingredients of Cheshunt compound, which you spray on seedlings to prevent damping off (ie death from rot). Copper sulphate is also used with hydrated lime as a fungicide in vinyards, under the name of Bordeaux mixture. Its also used as a seed dressing in farming and in sheep dips and for foot rot treatment, and for many other applications. Other copper salts are uses in pressure treated wood.

Silver and silver salts have a similar effect - but are more expensive. it was even proposed at one time to make hospital door nobs and fittings out of silver to combat MRSA and other hospital infections! You can even buy underware with silver threads for artic explorers etc, that you don't have to wash for several months. :D

 

It is used to combat blight in potatoes

 

Thanks all. So its primary use in farming is as a fungicide. It is particularly useful to know that it is used to combat potato blight.

I wonder how eco-friendly it is? I've heard tales it is not particularly good for the environment, but nothing very specific. I might have a good read up and see what else I can learn about it.

 

Its like anything else in life Clueless - a coin has two sides. It works because it kills fungus - but if it is not used carefully it will kill good fungus as well as bad fungus.