Message from NNF about Soil Depletion

[Forbes-Ewan, Chris]

There was considerable discussion on this listserv recently about possible
depletion of soil nutrients. Nutrition News Focus addressed soil depletion
last year (see message below my signature block).

Chris Forbes-Ewan

Senior Nutritionist
Defence Nutrition Research Centre
76 George St
Scottsdale  Tas  7260
Australia

Phone:	Int + 61 3 6352 6607	(03 6352 6607 within Australia)
Fax: 	Int + 61 3 6352 3044	(03 6352 3044 within Australia)

E-mail:	chris.forbes-ewan at dsto.defence.gov.au

The views expressed in this message are those of the author and do not
necessarily represent the position of the Defence Science and Technology
Organisation or of the Australian Department of Defence.


May 17, 1999 
NUTRITION NEWS FOCUS
"Nutrition news is important.  We help you understand it!"

Today's Topic: The Soil Depletion Song 

The refrain that depleted soils yield less nutritious fruits and
vegetables is one story that refuses to go away even though there 
is minimal evidence for it.  Vitamins are not found loose in the soil
just waiting for plants to soak them up into their roots.  Plants
synthesize their vitamins from a variety of building blocks in the
soil.  Minerals are taken up from the soil, but if there is a
deficiency in a mineral needed for growth of the plant, it simply
does not yield commercially viable amounts of fruits or vegetables.

Many people hold the belief that commercial fertilizers lack some
nutrients that are present in the soil or in organic fertilizers.
This is simply not true. Most commercial fertilizers are formulated
to give the highest yield of whatever crop they are used on.  While
there may be some variations in mineral levels of produce due to soil
content, only selenium varies markedly.  Some plants can take up lead
in very variable amounts depending on the immediate environment.

HERE'S WHAT YOU NEED TO KNOW: Depleted soil is not commercially 
profitable.  Therefore, farmers use fertilizers containing all the
needed nutrients for specific crops.  While organic farming may be
more environmentally friendly, there is no nutritional difference in
vitamins or minerals between crops grown under these two conditions.