12 March 2007

PSA: compost

Kalanchoe luciae
Beautiful weather, the miracle of March and daylight savings have combined to allow me to enjoy the garden after work earlier in the year. But today I am dreading it, because I should really turn the compost, and I'm feeling lazy.

Doesn't matter: I did a little research because I was worried about composting some big box store paperwhites, and this is what I found out from a recent review of the literature [Noble and Roberts, "Eradication of plant pathogens and nematodes during composting: a review," Plant Pathology 53 (2004), 548–568.]

  1. For 27 out of 32 pathogenic fungi, all six oomycetes, seven bacterial pathogens and nine nematodes, and three out of nine plant viruses, a peak temperature of 64–70°C and duration of 21 days were sufficient to reduce numbers to below, or very close to, the detection limits of the tests used.
  2. Several plant viruses were temperature-tolerant. These were CGMMV, /Pepper mild mottle virus/, /Tobacco rattle virus/, ToMV and TMV. TMV requires a peak compost temperature in excess of 68°C and a composting period longer than 20 days for eradication. However, TMV is degraded in compost over time, and can be eradicated after a composting period of 26 weeks, even at low temperature (31°C). ToMV in infected seeds can withstand over 70°C in an incubator for over 20 days. [TMV= tobacco mosaic, TomMV= Tomato mosaic; 31 C= 87.8 F; 70 C = 158 F]
  3. It is clear that the detection limits in most studies were quite poor, with infection levels of up to 5% likely to be undetected regularly.

My compost will never get hot enough no matter how much I turn it.


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3 Comments:

Blogger chuck b. said...

I've never gotten mine over 100 deg F. Sigh. I just try to be happy when it's warm. I think it's the proper layering of greens and browns that does it more than the turning.

3/12/2007 10:15 PM  
Blogger mmw said...

It's the layering and the small, uniform size of everything in the pile. On the other hand, you can just leave everything for 26 weeks and you'll be in pretty good shape. People who need total sterility should not be gardeners.

3/13/2007 12:50 PM  
Blogger lisa said...

I've read where adding a 5lb. bag of cheap dog food (main ingred. being corn meal) will heat up the composter. I tried it last year, and it definately accelerated things in mine (unsure @ actual temps, though).

4/05/2007 10:19 AM  

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