[Market-farming] Loss of Soil Carbon After Tilling

waldenfarm waldenfarm at bellsouth.net
Mon Oct 26 08:03:02 EDT 2009

Don't know of any graphs- probably because carbon loss after tillage differs 
because of different tillage methods, depth, bioactivity of the soil... But 
there is carbon loss after all tillage. Tillage incorporates relatively 
oxygen rich atmospheric air into the soil. This causes a population 
explosion in the soil biology and carbon compounds get processed at a faster 
rate than in untilled soil. The end product of carbon compound processing 
for food is carbon dioxide a gas.

Simplified, carbon compounds are processed by the soil biology and at the 
end of this chain it is converted to carbon dioxide, a gas. The CO2 in the 
soil readily leaves the soil through a number of mechanisms- gas dispersion, 
heating and cooling of soil, displacement of soil gases by water, etc.

As for your second question, mulching will not prevent carbon loss. Mulching 
has other benefits I'm sure you're aware of- preventing soil crusting. 
suppressing weeds, retaining soil moisture, slowing soil heat/cool cycle, 
reduce erosion, food at the surface for the soil ecosystem.

I also practice no till gardening- double dug beds one time 24 years ago and 
only do surface cultivation. And I've grown sweet potatoes in beds- it hurts 
me to tear up the beautiful soil structure diggin' taters, but they sure 
taste good! The only thing I know of to heal the soil (rebuild structure and 
replace lost carbon) is to add finished compost at or near the soil surface 
and plant or transplant a cool weather crop that will overwinter. Then 
adding mulch would help protect the soil from crusting and erosion until the 
soil biology can rebuild a stable structure.

I hope I haven't gotten too technical, but my thinking is that I have to 
know as much as I can about the soil and soil biologic processes to be able 
to manage it.

Enjoy those taters!

Alex McGregor
Walden Ridge, TN

----- Original Message ----- 
From: "Marty Kraft" <martyk at allspecies.org>
To: "Market Farming" <market-farming at lists.ibiblio.org>
Sent: Saturday, October 24, 2009 11:48 AM
Subject: [Market-farming] Loss of Soil Carbon After Tilling

> Does anyone know of any graphs or other data showing the rate of
> carbon loss after tilling? After i till a bed how quickly should it
> be covered by mulch to prevent carbon loss? I am practicing no-till
> gardening and i just dug two beds of sweet potatoes which is a lot
> like tilling. It's raining and i haven't mulched yet. I'll cover the
> soil when i can but this is a question that often arises. Does anyone
> know of a rule of thumb for this question?
> Where might i get this info?
> Marty Kraft, Kansas City 

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