tillage vs. no-tillage in California

To till or not to till in California

Having just returned from the Cover Crops, Soil Quality, and Ecosystems
Conference put on by the Soil and Water Conservation Society in Sacramento,
CA, I wanted to bring up an issue that is probably near and dear to many of
your hearts - that is tillage vs. no-tillage.  Although no-tillage
agriculture is now considered conventional practice in many (most?) parts of
the US, it hasn't caught on in California.  That became painfully obvious to
many of the conference participants after a farm tour of the southern
Sacramento Valley.  Tour buses passed by miles and miles of bedded fields
with cracked, naked soil which have waited all winter to be planted to cash
crops like tomato, corn, safflower, etc.  The sites on this tour obviously
provided alot of food for thought as discussions at the conference following
the tour focused more on tillage issues than they did on cover cropping.
Granted, no-tillage and cover cropping do fit together quite well, but they
are also practices that can be and are used independently.  While only a
minority of the conference participants appeared to have a religious
commitment to no-tillage and cover cropping, most non-Californians were
truely surprised and appauled that farming is still done this way in
California, the nation's leading agricultural state.

I am new to California and currently work on a research project (the
Sustainable Agriculture Farming Systems Project) at UC Davis comparing
conventional and alternative farming systems.  Over the first 8 years of the
project all of the farming systems have depended upon tillage (as nearly all
cropland in the Central Valley does).  And although there has been interest
in reducing tillage among people (farmers, farm advisors, and researchers)
involved with this project, little has yet been done to change this
conventional practice.  The primary hurdle to the use of no-tillage or
reduced tillage seems to be furrow irrigation which requires clean furrows,
free of any debris (or trash) that might block water flow.  Other factors
preventing adoption may be annual changes in bed widths with different crops
in a rotation and pest management problems (including weeds, insects, and
pathogens).  I don't think that it would be impossible to till less or use
no-tillage in California's Central Valley but the current lack of reduced
and no-tillage certainly indicates that there are serious problems that need
to be worked out.  I would appreciate hearing from others who have
experience with this issue, with a focus on the following questions:

1) In reducing dependence upon off-farm, non-renewable inputs should we
accept that the benefits of no-tillage (increased organic matter, improved
soil structure, carbon storage, less erosion) always out-weight the costs
(dependence on herbicides, increase in transplanting rather than direct
seeding, loss of cultivation as a weed management option)?

2) Is a no-tillage, organic system possible?



M. Sean Clark
Research Manager
Sustainable Agriculture Farming Systems Project
Department of Agronomy and Range Science
University of California
Davis, CA 95616
(916) 752-2023