Soil organic matter is the most important living reserve of carbon
(stored solar energy) in temperate climates, yet because carbon is the
stuff of living things -- particularly microbes -- soil organic matter
is a tremendously dynamic system. Many microbes thrive in an oxygen-rich
soil environment, and in the course of "earning their living" they
break down complex organic molecules and release them to the atmosphere
as carbon dioxide (called 'mineralisation').
Oxygen itself attacks soil organic matter, "burning" it slowly. Both oxygen
and microbes attack soil organic matter more aggressively when it is
warm. In fact equilibrium soil organic matter levels shift about 2.5%
for every 10 oC shift in *average* annual temperature. Warmer climates
have less soil organic matter than cooler ones.
In most row-crop situations a great deal of soil is exposed to both
the sun and the air -- more heat and more oxygen. Cultivation increases
oxygen levels even more, stimulating microbial activity. Heat, oxygen,
and busy microbes will convert important amounts of soil organic
matter to carbon dioxide, thereby reducing soil OM levels.
Soil OM does things like improve soil tilth and resistance to water
erosion (wet aggregate stability, etc), stores nutrients, retains
soil moisture, and so on. All of these things are pretty generally
agreed to be components of sustainability and to the extent that
they are degraded by conditions common in row-cropping, sustainability
almost certainly diminishes.
Row crops, too, are notorious for having rather limited root mass
to create *new* soil OM; in that respect they are different than
cereal crops and VERY different than sod crops.
> that sustainable farms are not financially feasible? I am very interested
Nope, other way around. Farms that aren't financially viable aren't
sustainable. The challenge of sustainable agriculture is to be
profitable while *simultaneously* improving soil health and system
biodiversity and reducing the need for off-farm inputs, particularly
> I think most people assume that if it is organic it
> must be sustainable. That on the spectrum of sustainability, organic is the
> pinnacle of achievement.
Most people *do* assume that. I just don't think it is a valid
assumption. The best, most sustainable farms I have ever been on
have all been organic -- truly inspirational stuff. I have also
been on so-called organic farms with 1050 acres of soybeans out of
1100 acres total (organic beans have fetched a very nice price the
last few years). Others have even less rotation than many conventional
farms. The sustainability of organic farms runs across the entire
range of sustainability, just like it does for conventional farms.
There is a lot of "organic by neglect" agriculture out there -- 'yeah,
it's organic, cuz I ain't put nuthin' on it.' is a comment I hear far
too often. That kind of "organic" just isn't sustainable, and it does
a major disservice to the majority of organic farmers who are making
excellent progress in developing healthy and naturally resilient
whole farm systems.
> Why wouldn't the national standards incorporate
> soil building requirements?
At a very minimal level they try. There would be no problem with
this if USDA standards were established as a *floor* not a *ceiling*
But agronomy and the organic industry are evolving significantly
faster than agencies have traditionally been able to respond; there's
an awful lot we simply don't understand about farm systems and soil
On the level of my strictly personal opinion, I think there is also
a side to this that is somewhat disturbing. Building soil health and
biodiversity on a farm while maintaining profitability is not easy.
There are a number of major processors and traders of organic food who
seem to want very low standards because they can get more ingredients,
cheaper, and still slap an organic label on it and lap up a nice
premium in the marketplace. Not of few of these folks have the ear
of the USDA bureaucrats developing the regulations. It all strikes me
as a bit like sex without love .... (-:
> Which certification organizations do or don't?
Of the major ones (with substantial amounts of food in the marketplace)
the Organic Crop Improvement Association (OCIA), Farm Verified Organic (FVO)
and Oregon Tilth seem to be the most dedicated *in practice* to long-
term system health, conscientious soil building, and such.