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http://www.i-sis.org.uk/OBCA.phpISIS Press Release 12/09/05 Organic Agriculture Enters Mainstream Organic Yields on Par with Conventional and Ahead During Drought Years But by far the greatest gains are due to savings on damages to public
health and the environment estimated at more than US$59 billion a year
Dr. Mae-Wan Ho puts the nail on the coffin on industrial agriculture

A fully referenced version of this article is posted on ISIS members’
website. Details here

Myths die hard
Scientists who should know better - if only they had kept up with the
literature - continue to tell the world that organic agriculture
invariably means lower yields, especially compared to industrial high
input agriculture, even when this has long been proven false (see for
example, “Organic agriculture fights back” SiS 16 [1]; “Organic
production works”, SiS 25 [2]).

Researchers led by David Pimenthal, ecologist and agricultural scientist
at Cornell University, New York, have now reviewed data from long-term
field investigations and confirmed that organic yields are no different
from conventional under normal growing conditions, but that they are far
ahead during drought years [3]. The reasons are well known: organic
soils have greater capacity to retain water as well as nutrients such as
nitrogen.

Organic soils are also more efficient carbon sinks, and organic
management saves on fossil fuel, both of which are important for
mitigating global warming.

But by far the greatest gains are in savings on externalised costs
associated with conventional industrial farming, which are estimated to
exceed 25 percent of the total market value of United States’
agricultural output.

Long-term field trials at Rodale Institute
From 1981 through 2002, field investigations were conducted at Rodale
Institute in Kutztown, Pennsylvania on 6.1 ha. Three different cropping
systems: conventional, animal manure and legume-based organic, and
legume-based organic. Plots (18 x 92 m) were split into three (6 x 92 m)
subplots, which are large enough for farm-scale equipment to be used for
operations and harvesting. The main plots were separated with a 1.5 m
grass strip to minimize cross movement of soil, fertilizers, and
pesticides. Each of the three cropping systems was replicated eight times.

The conventional system based on synthetic fertilizer and herbicide use,
represented a typical cash-grain 5-year crop rotation (corn, corn,
soybeans, corn, soybeans) that reflects commercial conventional
operations in the region and throughout the Midwest. According to USDA
2003 data, there are more than 40 million ha in this production system
in North America. Crop residues were left on the surface of the land to
conserve soil and water; but no cover crops were used during the
non-growing season.

The organic animal-based cropping represented a typical livestock
operation in which grain crops were grown for animal feed, not cash
sale. This rotation was more complex: corn, soybeans, corn silage,
wheat, and red clover-alfalfa hay, as well as a rye cover crop before
corn silage and soybeans. Aged cattle manure served as the nitrogen
source and applied at 5.6 tonnes per ha (dry), 2 years out of every 5
immediately before ploughing the soil for corn. Additional nitrogen was
supplied by the plough-down of legume-hay crops. The total nitrogen
applied per ha was about 40 kilograms per year or 198 kg per ha for any
given year with a corn crop. Weed control relied on mechanical
cultivation, weed-suppressing crop rotations, and relay cropping, in
which one crop acted as living mulch for another.

The organic legume-based cropping represented a cash grain operation
without livestock. The rotation system included hairy vetch (winter
cover crop used as green manure), corn, rye (winter cover crop),
soybeans, and winter wheat. The total nitrogen added to this system per
ha per year averaged 49 kg (or 140 kg per ha) per year with a corn
crop). Both organic systems included a small grain, such as wheat, grown
alone or inter-seeded with a legume. Weed control was similar in both
organic systems.

Yields no different except under drought conditions
For the first five years of the experiment (1981-1985), the yields of
corn grain averaged

4 222, 4 743 and 5 903kg per ha for organic-animal, organic-legume, and
conventional systems. After this transition period, corn grain yields
were similar for all systems: 6 431,

6 368, and 6 553 kg per ha. Overall, soybean yields from 1981 through
2001 were 2 461,

2 235 and 2 546 kg per ha; the lower yield of organic legume system is
attributed to the failure of the soybean crop in 1988, when climate
conditions were too dry to support relay intercropping of barley and
soybeans. If 1988 is taken out of the analysis, soybean yields are
similar for all systems.

The 10-year period from 1988-1998 included 5 years in which the total
rainfall from April to August was less than 350 mm (compared with 500mm
in average years). Average corn yields in those dry years were
significantly higher (28 percent to 34 percent) in the two organic
systems: 6938 and 7235kg per ha in organic-animal and organic-legume
systems compared with 5333 kg per ha in the conventional system.

During the extreme drought of 1999 (total rainfall between April and
August only 224mm), the organic animals system had significantly higher
corn yields (1511 kg per ha) than either the organic legume (421 kgper
ha) or the conventional (1100kg per ha). Crop yield in the organic
legume were much lower in 1999 because the high biomass of the hairy
vetch winter cover crop used up a large amount of the soil water. During
the 1999 drought soybean yields were 1400, 1800 and 900 kg per ha for
organic animal, organic-legume and conventional.

Other advantages of organic systems
Over a 12-year period, water volumes percolating through each system
were 20 percent and 15 percent higher in the organic-animal and organic
legume systems than in conventional. During the growing season in 1995,
1996, 1998 and 1999, soil water content was significantly higher in the
soil farmed using the organic legume system than in the conventional
system, accounting for the much higher soybean yields in the organic
legume system in 1999.

About 5.2 million kilocalories of energy per ha were invested in the
production of corn in the conventional system. Energy inputs for the
organic animal and organic legume systems were 28 percent and 32 percent
less. The energy inputs for soybean production in the organic-animal,
organic legume and conventional systems were similar at 2.3 mkcal, 2.3
mkcal, and 2.1 mkcal respectively.

Economic comparison of the organic corn-soybean rotation with
conventional corn-soybean systems from 1991-2000 showed that without
price premiums for the organic rotation, the annual net returns for both
were similar:$184 per ha for conventional, $176 per ha for organic
legume (Table 1).

Table 1. Annual costs per ha

Organic legume Conventional
Seed $103 $73
Fertilizers &Lime $18 $79
Pesticides $0 $76
Machinery $154 $117
Hired labour $6 $9
Total $281 $354
Revenue $457 $538
Net income $176 $184

Soil carbon at start (1981) was not different between the three systems.
In 2002, however, soil carbon levels in the organic animal and organic
legume systems were 2.5 percent and 2.4 percent versus 2.0 percent in
the conventional. The annual net aboveground carbon input (based on
plant biomass and manure) was the same in organic legume system and
conventional system (~9 000kg per ha), but about 10 000 kg per ha in
organic animal system. However, the two organic systems sequester more
of that carbon in the soil, resulting in an annual soil carbon increase
of 981 and 574 kg in the organic animal and organic legume systems,
compared with only 293 kg per ha in the conventional systems (calculated
on the basis of about 4 million kg per ha of soil in the top 30cm.).
Total soil carbon increase after 22 years was: 27.9 percent, 15.1
percent and 8.6 percent in organic animal, organic legume and
conventional systems.

Soil nitrogen levels started at 0.31 percent in 1981. By 2002, the
conventional system remained unchanged, while organic animal had
increased to 0.35 percent and organic legume system to 0.33 percent.
Using 15N to measure retention of N in soil it was estimated that 47
percent, 38 percent and 17 percent respectively of the nitrogen from
organic animal, organic legume and conventional was retained in the soil
each year after application. This matched the decreased amount leached
from the organic soils.

Four herbicides were applied in the conventional system: atrazine (to
corn), pendimethalin (corn), metolachlor (corn and soybeans) and
metribuzin (soybeans). From 2001 to 2003, only atrazine and metolachlor
were detected in water leachates collected from conventional systems at
levels in excess of 3 parts per billion, exceeding maximum contaminant
level set by US EPA for atrazine (no level has been set for metolachlor).

Soils farmed with the two organic systems had greater populations of
spores of the beneficial Arbuscular mycorrhizal fungi, shown to enhance
disease resistance, improve water relations and increase soil aggregation.

Large amounts of biomass (soil organic matter) are expected to
significantly increase soil biodiversity. Microarthropods and earthworms
were reported to be twice as abundant in organic versus conventional
agricultural systems in Denmark. Earthworms and insects create holes in
the soil that increase the percolation of water into the soil and
decrease runoff.

Labour requirements
Each system was allowed 250 “free” family labour per month; while the
cost of hired labour was $13 per hour. With organic farming system, the
farmer was busy throughout the summer with the wheat crop, hairy vetch
cover crop, and mechanical week control but worked less than 250 hours
per month). In contrast, the conventional farmer had large labour
requirements in the spring and fall, plating and harvesting, but little
in the summer months.

Increase in labour input may range from 7 percent to a high of 75
percent in organic compared to conventional systems. But in situations
where human labour is not in short supply, this too can be an advantage
of organic agriculture in creating employment.

The externalised costs of conventional agriculture not taken into account By far the biggest gains from organic agriculture arise from the savings
on the damages to public health and the environment due to the use of
agrochemicals in conventional agriculture.

The National Organic Standards Program in the United States prohibits
the use of synthetic chemicals, GMOs and sewage sludge in organically
certified production.

As Pimenthal points out [3], the estimated environmental and healthcare
costs of pesticide use at recommended levels in the US is about 12
billion every year. According to the National Research Council [3], the
cost of excessive fertilizer use is $2.5 billion per year, while the
estimated annual costs of public and environmental health losses related
to soil erosion greater than $45 billion [5].

The total externalised cost of conventional agriculture per year is
$59.5 billion. This represents 27.4 percent of the entire agricultural
output ($217.2 billion in 2002 [6]).


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