Forum—An Experiment Continues
Field technician Emilio Chavez drives a tractor-drawn stalk puller that uproots
plants after harvest.
Farming is perhaps civilization's longest scientific experiment. Each
growing season marks a new field test during which farmers deploy the practices
and tools that might succeed. Final results must wait for the harvest; until
then all the farmer can do is try. "To try" is the meaning of the
Latin verb experiri, the source of our word experiment.
When a scientific experiment fails to meet a researcher's expectations, the
failure can be beneficial if it opens an unexpected door to knowledge. But for
a farmer or community of farmers or a society dependent on farmers,
agricultural failure can pack a high, sometimes catastrophic cost. Avoiding
this cost--and finding farming methods that can succeed despite adverse weather
and other conditions--are primary reasons why farmers and scientists should
often work in close partnerships.
This month's cover story tells of a productive though informal partnership
begun in 1992 in the Lower Rio Grande Valley of south Texas. That's when
researchers at ARS' Subtropical
Agricultural Research Laboratory in Weslaco began developing and testing
new conservation tillage systems. The systems' key components are tools and
practices that save time, fuel, and labor by reducing tillage needs and
maintaining a crop residue cover to conserve soil and water.
Something else arrived in the valley about 1992: the most recent of the
severe droughts common to the area's semiarid climate. The drought has taken an
increasing toll on crops and livelihoods in the valley on both sides of the
international border. But with it has come some important, if costly,
By dramatizing the new tillage systems' relative advantages over
conventional systems, the drought has persuaded more valley growers to switch
to conservation tillage on cotton, sorghum, and corn.
When the researchers planned their experiments, they knew conservation
tillage could work only if the systems were compatible with the climate and
other unique factors and grower requirements. For example, they knew the
systems must enable growers to prevent their harvested sorghum and cotton
plants from resuming growth through the valley's mild winters. Otherwise, these
plants could harbor pests and deplete nutrients and moisture needed by summer
"At the time, the moldboard plow was the only available tool,"
says Weslaco agronomist Jim Smart. "We needed a substitute that would kill
the plants without deeply tilling the soil and burying the residue." The
researchers began investigating two commercially available tools as potential
The tools, stalk pullers and row stalkers, serve as tweezers for plant
stalks. Arizona Drip Systems, Inc., of Coolidge, Arizona, invented the stalk
puller for quickly removing cotton plants after harvest in fields watered with
subsurface drip irrigation. Using a plow to kill the plants would tear up the
costly drip-irrigation lines buried beneath the surface. The stalk puller grabs
each plant low on the stalk and pulls out the crown and firmly attached roots.
A similar tool, the row stalker, is manufactured by DL Industries, Inc., of
"As far as I know, ARS brought the first stalk pullers and row stalkers
to the Lower Rio Grande Valley," Smart says. The tools' sales have
increased, signaling not only the rise of the new tillage systems but also the
kind of economic benefits that often accompany the transfer of research
technology. Barbee Neuhaus Implement Co. in Weslaco has sold several hundred of
these tools. Interest is rising in other areas, such as central Texas and
By 1994, a couple of years of field tests showed the new tillage systems had
potential. But a grower would have to learn why and how they could work--and
what modifications they might need.
So ARS and Texas A&M University scientists began demonstrating the
systems at field days. At Weslaco last March 26, about 300 Texan and Mexican
growers attended the largest field day ever held at the ARS lab. "It used
to be, if you got a couple dozen growers at a field day on any topic, it was a
success," says Smart.
Education hasn't been a one-way flow. "Because of the marginal economic
returns of many farmers, it's best for us to test cropping-system ideas first
on research plots," says ARS soil scientist Joe Bradford. "Later on,
through on-farm trials, growers can implement systems, improve them, and
transfer the technology among themselves. If growers get together in a group
and talk, everyone doesn't have to make the same mistakes.
"Identifying specific problems often has to come from the farmers
themselves," Bradford adds. "As much as we can, we work with them to
see how they can overcome serious problems. Since other growers are likely to
have similar problems, this helps us develop better systems."
It's too soon to be certain, but the improved systems appear to be helping
growers design more sustainable agricultural experiments for their valley. --
Jim De Quattro, ARS Information
This page last updated June 2005.