Subject: UW release: acid linked to soil aging

From: BILL DUESING <[email-masked]>
Date: Thu, 11 Mar 1999 04:42:15 -0500

Thanks for this post and Steve's comments.

The CT Agricultural Experiment Station grew vegetables on research plots
for twelve years.  One plot had 10-10-10 and limestone added every year. 
Another had one inch of leaf compost added each year.  After twelve years,
the yields from the two plots were about the same, but the composted soil
had a slightly higher pH, twice as much organic matter, lower density and
more water-holding capacity.

I heard a geologist lecture on soil weathering and explain how the minerals
most important for agriculture were eroded first from soil particles. Since
the acids lichens produce slowly erode rocks (chemical weathering) it is
not surprising that nitric acid also erodes the tiny rocks which make up
the mineral part of soil.

This all may be connected with the great results that some growers report
from the use of quarry dust (basalt) as a soil amendment.  It is a  great
source of fresh, unweathered minerals.

Bill Duesing

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