[diggerjoe]

If thunder and lightenng  is about the rainfall carry a very small amount of nitric acid from the the electrical activity which is good for the plants or did i dream that in a science lesson years ago

[JayG]

Well remembered Joe!

The high voltage discharges cause atmospheric nitrogen to combine with oxygen to form various oxides of nitrogen which then dissolve in the rain to form very dilute nitrous and nitric acids.

Another way of "fixing" nitrogen, and the way the sky is looking at the moment I think we are about to get a fix here! 

[mumofstig]

Is'nt all rain slightly 'acid' nowadays anyway? 

[prakash_mib]

Is'nt all rain slightly 'acid' nowadays anyway? 

yes they are but sulphuric!!! not nitric anyway I assume   :blink:

[JayG]

Think so; mainly dissolved sulphur oxides from fossil-burning power stations but also others from cars etc.

Not as bad as it used to be though (we are led to believe!) 

[mumofstig]

Many moons ago I toured the Black Forest region Germany and all the conifer trees were dead from acid rain

My plants didn't die, they loved it, so it must be ok again now

[Babstreefern]

Sorry mumofstig, its not acid rain that killed some of the Black Forest, we were there yonks ago, and my OH had to disappear behind a tree to relieve himself

[mumofstig]

     he must have had a lot of local beer cos half the forest was dead   

[MOLUSC]

I have read the pros and cons of tap water (with additives) versus rainwater.
It depends greatly on where you live, if you live in a densely populated area (factories,motorway etc) then the rainwater is likely to be contaminated (acid rain) but out in the countryside definately less so.
However i think it is more likely to do with the volume of  rain water compared with that of a watering can or hose that our plants like.

I have just read that 1mm of rain fall is equal to 1Litre per square meter .
My quarter plot is only about 72 square meters , thats 72 litres of water from 1mm of rainfall.

25mm (an inch) of rainfall would equal 1800 litres of water!