March 2008 — Can organic cropping systems
be as productive as conventional systems? The answer is an unqualified,
“Yes” for alfalfa or wheat and a qualified “Yes most of the time” for
corn and soybeans according to research reported by scientists at the
University of Wisconsin-Madison and agricultural consulting firm AGSTAT
in the March-April 2008 issue of Agronomy Journal.
The researchers primarily based their answer on results from the
Wisconsin Integrated Cropping Systems Trials, conducted for 13 years
(1990-2002) at Arlington, WI and 8 years (1990-1997) at Elkhorn, WI.
These trials compared six cropping systems (three cash grain and three
forage based crops) ranging from diverse, organic systems to less
diverse, conventional systems.
The cash grain systems were:
- conventional continuous corn,
- conventional corn-soybean, and
- organic corn-soybean-wheat where the wheat included a leguminous cover crop.
The three forage based systems were:
- conventional corn-alfalfa-alfalfa-alfalfa,
- organic corn-oats-alfalfa-alfalfa, and
- rotationally grazed pasture.
In this research they found that: organic forage crops yielded as
much or more dry matter as their conventional counterparts with quality
sufficient to produce as much milk as the conventional systems; and
organic grain crops: corn, soybean, and winter wheat produced 90% as
well as their conventionally managed counterparts.
In spite of some climatic differences and a large difference in soil
drainage between the two sites, the relatively small difference in the
way the cropping systems performed suggested that these results are
widely applicable across prairie-derived soils in the U.S. upper
Midwest. The researchers also compared their results to other data
analysis done on this topic in the U.S. Midwest.
Although researchers found that diverse, low-input/organic cropping
systems were as productive as conventional systems most of the time,
there is a need for further research, according to the study’s author
Dr. Joshua L. Posner, University of Wisconsin.
“There continues to be improvements in weed control for organic
systems that may close the gap in productivity of corn and soybeans in
wet seasons,” Posner says. “On the other hand, technological advances
may accelerate productivity gains in conventional systems that would
outstrip the gains in organic systems even in favorable years.”
The true question of whether organic cropping systems are as
productive as conventional systems is a dynamic question and one that
requires continual reevaluation.
Source : American Society of Agronomy