Soil Quality; Con't
Charles Benbrook (benbrook@hillnet.com)
Sat, 18 Feb 1995 12:52:45 -0800 (PST)
Sandy soils in hot irrigated regions are among the most productive in the
world. Some people commenting recently imply that the definition of soil
quality should be heavily weighted toward capacity to support high yields
(or some yield) with little or no inputs. In a world with 6 billion
people and growing, much of agriculture is going to have to be very
intensive, and support very high yields relative to what any soil could,
or would if left in a natural state, or if original soil properties were
re-created. This is a reality of life, planet earth. So I think the
capacity to support high yields with inputs that are accessible, and
relatively sustainable is an important soil quality attitbute. Also,
let's remember that many of the world's people, and a lot of land are in
hot, arid, or semi-arid regions where soils will never build up the
organic matter content and tilth common in the corn belt; and also
remember that the richest soils (in their natural state) tend to be where
there is lots of rain, and temperate climates, which can grow great
crops, but have their limits too related to growing season, climate,
pests, etc. You can make a sandy, irrigated soil in the west out-produce
the corn-belt in terms of biomass any day, in effect raising production
maybe 10 or even 15 fold over what it would be under more or less natural
conditions, but modern scientific ag can not do that in areas where
nature dealt such a good hand to start with. Contemporary example --
roughly natural grass operations under rotational grazing in upper
midwest are producing roughly as much milk/meat per acre (and certainlky
cheaper) that the highest of the high tech dairies, where alfalfa, corn,
and cows are all on drugs.
In case of irrigated potatoes, relative to potato production in
humid regions of upper-midwest, Maine, and elsewhere in the U.S.,
Washington state and Idaho potatoes can be grown with much less use of
pesticides, for a host of natural reasons. Just as the region's sandy
soils are a soil quality disadvantage, the region's climate is a "soil
quality to grow potatoes" advantage. So yes, a full appraisal of soil
quality has to be against some benchmark, some defined, desireable
outcome, and a host of relative factors need to be taken into account.
Again in potatoes/Northwest the region's principle soil quality problem
is propensity to leach nutrients and water, and low organic matter
content, which lessens chance for microbial biocontrol of soil pathogens,
which can hammer potatoes. So the challenge is to find systems with
cover crops, composts, etc which can raise the organic matter level of
these soils, thereby reducing this fundamental constraint and also
helping lessen propensity to leach. Will this
cost money, take energy/biomass? Yes. Does growing organic strawberries
in the same region under plastic? Yes. Which is more sustainable? It
depends on market demand in the near term more than anything else, and
competition, of course.
By focusing on very long-term sustainability issues, and placing
great emphasis on whether a given system, practice, technology, type of
farm is theoretically sustainable forever, we miss the chance to gain
better understanding and do a better job of managing issues in "our own
backyard". Backyard in the sense of time (our lifetimes) and place (the
U.S. or the region we work in).
The Pierce/Larson paper somebody mentioned defines the concept of
a minimum data-set to measure/track changes in soil quality. Its a great
paper, was done for a conference in Thailand in 1991 I think, and has
since been published. Contact Fran at Mich. State Univ. soil science
dept. It is definitely one of the most important papers in a decade, and
should be up and accessible at a bunch of ftp, gopher, etc cites. It does
have lots of tables/complex graphics though. Could someone from Mich. or
Minn. ask Bill or Fran how best to get a copy, and post it so others can
have it. I would like to add it to my soon to be up WEB page.
Also, their paper and the concepts in it were the foundation for
the Northwest Area Foundation supported project on soil quality
indicators being managed by John Gardner out of North Dakota's Carrington
ag res. station. How about an update from someone involved in that
project? They have been collected baseline soil quality datasets in 4
states for I think 3 years now, or at least two.
Returning to my initial question, is anyone thinking about soil
quality as a farm bill issue?
And, does everyone know about the soil quality conf. in mid-March
at Colorado State Univ., sponsored by the soil ecology chapter of the
ecological society, I think. The program looks excellent, and I wish I
could be there. Maybe someone in this dialogue who will would be willing to
post some summaries of what transpires.
chuck