[Terrapreta] Does Terra Preta Increase Drought Tolerance?

[Tom Miles]

Joe,

Increase in water holding capacity is one of the advertised features of
biochar. I've seen measurements of water holding capacity of char compared
with other materials but no comparisons of water retention in specific soils
containing various concentrations of biochar. Water retention certainly is a
an argument given for biochar in the dozens of advocacy blogs and articles
but I don't see any field data yet. I would think that University of Georgia
would be working with biochar in local soils.     

According to the Cornell Biochar page "beneficial effects of biochar on both
soil microbial functions and soil water availability are highly likely but
not yet sufficiently quantified to be effectively manage"
http://www.css.cornell.edu/faculty/lehmann/biochar/Biochar_home.htm

Their current research in Kenya, Zambia, and Colombia should show something
about water retention.  

One of the more clear illustrations of water effects is in Julie Major's
February 2006 seminar presentation:
Improving soils with biochar: General considerations and current research
efforts
http://terrapreta.bioenergylists.org/major2006

The only data I have seen in public information available from recent
conferences in Australia is a table of how increasing soil organic carbon
(OC) increases soil water storage capacity. See Christine Jones, "Soil
carbon means WATER - for all" in her presentation "Carbon, air and water -
is that all we need?" 'Managing the Carbon Cycle' Katanning Workshop 21-22
March 2007
http://terrapreta.bioenergylists.org/amazingcarbonKatanning
 
Maybe those on the list with better knowledge of current research can tell
us about water retention and drought tolerance with different soils. 

Tom
 

> -----Original Message-----
> From: joe ferguson [mailto:jferguson at nc.rr.com]
> Sent: Thursday, July 05, 2007 7:37 AM
> To: Tom Miles
> Cc: terrapreta at bioenergylists.org
> Subject: Re: [Terrapreta] Does Terra Preta Increase Drought Tolerance?
> 
> Is there any data on the impact of char on moisture retention in
> various
> soils?  I'm assuming that the drought areas of the US southeast are
> predominately coastal plain and sandhills as well as red clay in the
> higher elevations.
> 
> Joe
> 
> Tom Miles wrote:
> >
> > We read these days about the drought in the Southeastern part of the
> > United States especially in areas like Alabama and Georgia, where
> > rainfall is 14 inches (355 mm) compared with a normal 36 inches (914
> > mm). Crops of corn and cotton are devastated much as they are in
> > drought areas throughout the world. University of Georgia is probably
> > very occupied with drought related issues.
> >
> >
> >
> > Can biochar applications help increase drought tolerance? Could
> > biochar prevent or decrease crop loss caused by drought?
> >
> >
> >
> > That could be a compelling reason for US farmers to try terra preta.
> >
> >
> >
> > Tom Miles
> >