[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[SANET-MG] organic production works
http://www.i-sis.org.uk/organicproductionworks.phpISIS Press Release
Organic Production Works
A new study shows organic production outperforms conventional in crop
yield, soil fertility, pest reduction and economic return. Rhea Gala reports
Sources for this report are posted on ISIS members’ website.
Transition to organic production
Increasing public demand for organic products attracts premiums for the
certified organic farmer, causing hard-pressed conventional farmers to
consider going organic.
In the US, a 20% annual growth rate caused sales of organic produce to
reach $8 billion in 2001; and incentives to farmers to go organic are
offered in the 2002 Farm Bill, including cost sharing, and direct
payments for conservation practices, such as longer crop rotations.
Scientists Kathleen Delate of Iowa State University and Cynthia A.
Cambardella of the US Department of Agriculture assessed the
agroecosystem performance of farms during the three-year transition it
takes to switch from conventional to certified organic grain production.
Strategies for lowering the risk of yield loss during this period have
been researched, as productivity has been found to decrease initially
when fertilizer and pesticide applications are withheld. But
productivity generally improves in successive years under organic
management to equal that in conventional farms. The study found that
organic grain crops can be successfully produced in the third year of
transition and that additional economic benefits can be derived from
expanded crop rotation.
The experiment, lasting four years (three years transition and first
year of organic certification), tested the hypothesis that organic
systems relying on locally derived inputs are capable of providing
stable yields while maintaining soil quality and plant protection
compared with conventional systems with less diverse crop rotations and
greater levels of external, fossil-fuel based inputs. The experimental
design involved a completely randomized four replications of four
different cropping system treatments.
The researchers looked at the effects of organic farming practices,
including crop rotation, cover cropping, compost application, and
non-chemical weed control on soil fertility, crop yield, and grain
quality compared with the conventional system. They assessed pests and
plant response under various crop rotations, and determined which
certified organic drop rotations reduced the risks from low yield and
improved soil properties and economic returns.
Organics performed as well or better
During the four-year period, corn yield in the organic system averaged
91.8% of conventional corn yield and soybean yield in the organic system
averaged 99.6% of conventional soybean yield. By year three, there was
no significant difference between organic and conventional yields; and
both organic corn and soybeans exceeded conventional yields in the
fourth year (the first year after certification).
In the initial year of transition, an economic advantage could be gained
by planting legume hay crops or crops with a low nitrogen demand in
fields with low productivity, to increase fertility for the following
corn crop. In the second year, yield differences were mitigated by
rotation effects and compost application, providing sufficient nutrients
for the organic grain crop. The yields in year three were similar, but
the importance of a soil-building cover crop, or legume grass mixture
such as the oat-alfalfa mixture used in this study was apparent in the
fourth year when organic corn and soybean yields out-performed the
The researchers thought that timely weed management and sufficient
levels of nitrogen, phosphate and potassium in the organic system
contributed to good yields during transition. Yield increases were
obtained after three years because of available nitrogen due to organic
amendments, such as composted pig manure and the inclusion of forage
legumes and other green manures in extended crop rotations.
Soil fertility depends on the constant renewal of biologically available
nitrogen to replenish the organic nitrogen pools for plants to absorb.
Total nitrogen levels showed an increase of 457 kg per hectare in
organic soil over four years, or an average increase of 114 kg N per ha
per annum, sufficient to maintain organic nitrogen pools in this system.
Total organic calcium increased 9% in organic soil over the transition
period, with no significant increase in non-organic soil.
The researchers found weed pressure in the organic corn and soybean
systems was manageable, and that it was less in organic soybean than in
corn plots where rye was not used as a cover crop. In the soybean-rye
rotation, weed densities were equivalent to conventional systems in the
first two years, and significantly less in the third year. Grass and
broadleaf weed populations varied between the organic and conventional
systems each year, but the impact on yield was considered negligible.
Corn borer and bean leaf beetle populations were similar between
systems, again with no effect on yield.
Economic returns in the organic corn-soybean-oats/alfalfa and the
organic corn-soybean-oats/alfalfa-alfalfa rotations were significantly
greater than those in the conventional corn-soybean rotation, as organic
soybean commands premium prices in the organic rotation due to increased
A previous study had found enhanced soil fertility and higher
biodiversity were correlated with less dependence on inputs in the
organic systems, reducing fertilizer and energy inputs by 44% and
pesticide by 97%.
The study continues
This study is ongoing, and will continue to examine the effect of crop
sequence and length of rotation on long-term pest disruption and
attraction of beneficial insects into the organic systems. Earlier work
by Miguel Altieri at University of California, Berkeley, showed that
greater biological control should occur in organic systems that maintain
diverse biota through minimal pesticide use (see "Agroecology vs
ecoagriculture", ISIS report www.i-sis.org.uk).
Potential food quality changes will also be monitored over time, so that
assessments of the advantages of organic production over conventional
systems can be brought more to the foreground of the debate on organic
versus conventional production. As organic farmers produce high quality
food without conventional inputs from agribusiness, agribusiness has a
vested interest in denigrating organic systems on any account. This
research is essential in countering the corporate disinformation campaign.
The Institute of Science in Society, PO Box 32097, London NW1 OXR
telephone: [44 20 8452 2729] [44 20 7272 5636]
General Enquiries email@example.com - Website/Mailing List
firstname.lastname@example.org - ISIS Director email@example.com
MATERIAL ON THIS SITE MAY BE REPRODUCED IN ANY FORM WITHOUT PERMISSION,
ON CONDITION THAT IT IS ACCREDITED ACCORDINGLY AND CONTAINS A LINK TO
To unsubscribe from SANET-MG:
1- Visit http://lists.sare.org/archives/sanet-mg.html to unsubscribe or;
2- Send a message to <firstname.lastname@example.org> from the address subscribed to the list. Type "unsubscribe sanet-mg" in the body of the message.
Visit the SANET-MG archives at: http://lists.sare.org/archives/sanet-mg.html
For more information on grants and other resources available through the SARE program, please visit http://www.sare.org.