Question

Thomas Bjorkman tnb1 at cornell.edu
Wed Nov 3 13:46:04 EST 1999


This is a major question in the compost industry. As far as doing the NPK
analysis, most fertilizer testing labs can do that just fine. In fact, I
think that they have to use such a certified lab if they want to sell it
as a fertilizer with a guaranteed analysis in most states. 

Biosolids are highly controversial for land application for two main
reasons--heavy metals and microbial pathogens. (OK, I'm ignoring the
number one reason--its raw material.) 

In these two areas the Compost Council is trying to establish standards.
After a great deal of analysis and negotiation they are close to
promulgating the TEST PROCEDURES that should be used. They are far from
determining that are acceptable values in those tests.

Control of heavy metals depends almost entirely on controlling source
contamination. Some cities have pulled it off quite well, including the
one where I work. 

Control of microbial pathogens depends on the composting procedure used at
the treatment facility. Some procedures work better than others, and some
managers are careful enough, and some are not.

For plant growth, one of the main problems is an excess of simple
carbohydrates. These carbohydrates are most quickly assimilated by
barcteria. They are often plant pathogens. Furthermore, as they grow, and
make proteins, they use up available nitrogen. Seedlings weakened by
nitrogen deficiency can easily succumb to bacterial diseases, and often
also to (fungal) damping off. The solution to this one is to use truly
mature compost, where the simple carbos have been consumed, and the more
complex ones, which tend to support beneficial fungi, remain.

The pathological research in this area has largely come from Harry
Hoitnick at Ohio State. Practial horticultural work has been done by a
number of people, but I would emphazise that of Nancy Roe, now at Texas
A&M, and Monica Ozores-Hampton at U. Florida. 

In article <v04020a03b445ec4dfcff@[141.233.128.167]>,
wise at VAXA.CIS.UWOSH.EDU (Bob Wise) wrote:

> To all,
>         I'm looking for a standard procedure for testing the fertilizer
> value of a soil supplement derived from treated sewage biosolids.  A local
> sewerage district is considering processing and marketing their product.
> One of the many questions they need to answer is what effect does it have
> on plant growth.  Does anyone know of a standard set of conditions (plant
> species, soil type, watering regime, etc) that is used for this type of
> study?  I can come up with my own design, but I'd hate to reinvent the
> wheel if I don't have to.
-- 
Thomas Björkman    
Dept. of Horticultural Sciences   
Cornell University




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