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Re: [compost_tea] Re: NOP regulations



Hi all -

I can't talk about what is going on in the Compost Tea Task Force.  Not kosher to make statements as if there were decisions being made, when there aren't any decisions being made yet.   Hopefully there will be a recommendation soon.

So, if people can continue to agitate gently with their political connections, it might help. 

Based on my opinion, which has been modified by the discussions in the task force, the major points that need to be in regulations are:

If the compost used to make tea is documented to be made according to certification requirements (i.e., made according to regs, whether organic or USDA),

OR

if the compost is tested for human pathogens and found to contain fewer than the acceptable levels as established by EPA or USDA standards,

THEN

compost tea made from those sources can be used without restriction.

So far so good.  If you make sure your compost was made correctly, no problem.  with or without manure. 

The CURRENT USDA - NOP regs are for compost tea MADE WITH MANURE-BASED COMPOST, the 120 day rule applies.  Tea made with compost that does not contain manure can be used without restriction.  If certifiers are making rules different from that, they need to talk to Bob Pooler, of the USDA - NOP. 

Again, if composted correctly, pathogens should be out-competed, consumed, and reduced below levels of concern in the compost.  The tea from such compost can be used without restriction.

The USDA just finished a study - from Pat Milner's program - that showed that compost that reached temperature for an adequate period of time resulted in reduction to acceptable levels of the human pathogens.  Problem is, the USDA doesn't recognize that things other than temperature can be involved in reduction in pathogens. 

Why hasn't the USDA recognized this?  Because there are more than one or two  factors that have to be determined to know that the habitat is not appropriate for the growth of human pathogens.  

My view - which not everyone agrees with - is that you have to have adequate aeration, adequate microbial activity, and adequate protozoan numbers in order to know for certain that the human pathogens, if present to begin with, have been reduced. 

We have some data to show that is the case, but we haven't tested all the possible situations. 

We have data to show that molasses does NOT "cause E. coli to grow" as has been claimed by one other researcher.  Don't pick on molasses as the only thing that E.coli can utilize, human pathogens can grow using a number of different sugars.  But it has to be more than just that one factor that will allow E. coli to grow.  The other factors have to be correct for E. coli to grow. 

So, lack of proper aeration and lack of the other competitive organisms that outcompete and consume human pathogens.  Aerobic organisms - in high diversity and in high numbers - outcompete and consume human pathogens most readily. 

OK, one more caveat - if the conditions in the brew are very anaerobic, human pathogens are also not able to grow.  But, very anaerobic brews will not remain anaerobic.  There will be a period of time when that anaerobic brew will be back in range to allow human pathogen growth.  Are the human pathogens then able to reach high enough numbers to be a problem?  Don't know.  Need data.  My feeling is, let's not allow use of those anaerobic brews until until someone does the necessary research to let us all know what's going on. 

Now, a couple other things to think about -

When you start to deal with aeration, you have to pay attention to temperature and air pressure because they determine maximum oxygen concentration in the water. 

You have to pay attention to microbial growth, because microbes use oxygen and respire carbon dioxide.  Microbial growth may drop oxygen low enough that human pathogens can outcompete the aerobic microbes.  When you deal with microbial growth, you have to pay attention to temperature (microbial growth rate increases with temperature typically) and amounts of foods added (more food,  more microbes).  

So really, in order to assess the habitat and make sure it is not conducive to human pathogen growth, you have to assess:

temperature
air pressure
oxygen concentration
microbial foods
bacteria, fungi
protozoa

Did I forget anything? 

Temperature should be monitored hourly through the brew.  How fast will the organisms grow, and how much oxygen can the water hold?

Air pressure should be known at the beginning of the brew (temp and air pressure will tell you the max oxygen possible in the brew.  There may be times, with compost that you know contains pathogens, where you will not be able to brew, because the temperature is too high, and therefore oxygen concentration will be too low at the start of the brew to select against the pathogens)

Oxygen concentration should be monitored throughout the brew.  We have seen 5.5 to 6 ppm to be the "cut-off" when dealing with typical aerobic microbe to facultative anaerobic microbe growth conditions.  Valid in all situations?  What is you have a fermentative lactic-acid bacteria community of organisms?

Microbial foods should be added relative to the set of microbes in the compost, which will determine the growth achieved during the brew cycle, given that oxygen concentration that can be maintained by the machine through the brewing cycle.  This is information machine manufacturers should determine, and which all the tea machines manufacturers of AACT have performed.  They haven't all put their data on their websites.  The machine makers that don't have data on their websites are the ones whose machines can't achieve the microbial growth to prevent pathogens from growing.  The people showing their data are the ones doing the work to make sure their machines CAN maintain aeration, microbial growth, and suppress human pathogens. 

The set of microbes, including protozoa, in the compost and thus the tea should be known.  Plate counts are not appropriate for assessing bacteria or fungi in any environmental material since viability is not what is needed, but activity and total biomass.  As methods are developed, molecular methods must be used to assess species composition. 

Typically production methods for commercial composting should be such that each batch of compost produces the same set of microbes, within certain ranges.  There may be variation based on starting materials and initial chemical content, but these can be determined, and the variation in microbial content known as seasons change. 

The research that needs to be done is on composts that are of questionable microbial content, where some level of significant human pathogen contamination is left.  We need research to assess what precisely is the habitat that allow human pathogens to be reduced in number and activity, and what habitat allows human pathogens to grow.

I've outlined the information needed for research to do the job of figuring out what conditions select against human pathogens.  If people want to do bacterial or fungal plate counts so they can prove to themselves just how pointless it is to do those determinations in order to assess the response of microbes in compost or compost tea, fine. 

The best approach we have for assessing human pathogens is E. coli plate counts or broth MPNs.  That use of plate count methods is appropriate.  We know the conditions that allow E. coli to grow in lab cultures.  But don't mistake those special conditions as being reflective of what happens in real world conditions.   Stop imagining that lab cultures represent real world situations. 

So, that's where I think we're at, without being in any way specific about what's being said or done in the CTTF. 

Any questions, or places my logic is not clear, please discuss with me.

I am putting a summary of the regs for different state's irrigation water on the SFI website.  If conventional growers can water crops with those levels of E. coli - and therefore potentially human pathogens - then higher standards should not be imposed on organic growers.  The summary is based on information sent out by Pat Milner of the USDA. 

Elaine Ingham
President, Soil Foodweb Inc.
www.soilfoodweb.com
SFI Oregon, USA
SFI Australia
SFI New York
SFI Europe
SFI New Zealand

"Hope is not a feeling. It is not the belief that things will turn out well, but the conviction that what we are doing makes sense, no matter how things turn out."   --  Vaclav Havel, former President of the Czech Republic


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