[compost_tea] Re: Sustainable Farming News & Biological Agriculture Information. >
Regarding David Eyre's comment about adjusting the pH of compost, microbes =
seem to do what they do and maintain a high pH in the process. This summ=
er, I made very high strength compost tea and used it as a "complete" hydro=
ponic nutrient solution to grow tomato plants. My starting water has a p=
H around 7.8. When brewing it went to 8.5 and even up to 9.0 at one poin=
t. After brewing it went down to about 8 and stayed there. With one b=
atch of tea, I reduced the pH with citric acid, to 4.5. Four hours later=
, the pH was back up to 8. I couldn't keep the pH down!
In the other batch, I used the tea with a pH of 8. I was still able to=
grow tomatoes pretty successfully despite the fact that the pH was so high=
. I suspect that either the microbes in the rhizosphere bring the pH do=
wn right at contact with the roots, and/or the microbes are producing chela=
tes/siderophores that are assisting with transport of the nutrients into th=
e roots, even when the pH is high (this was the case with iron in a 1960's =
study I saw)...Perhaps this happens with other nutrients as well? Any bo=
dy have thoughts on this?
Stacy
Stacy Tollefson
PhD Candidate Agricultural and Biosystems Engineering
University of Arizona
Controlled Environment Agriculture Center (CEAC)
Received on Tue Dec 20 2011 - 01:47:34 EST
This archive was generated by hypermail 2.3.0
: Tue Feb 07 2012 - 13:58:14 EST