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  • From: "Tradingpost" <tradingpost@gilanet.com>
  • To: livingontheland@lists.ibiblio.org
  • Subject: [Livingontheland] Organic Yields on Par with Conventional and Ahead During Drought Years
  • Date: Fri, 16 Sep 2005 09:54:28 -0600


http://www.i-sis.org.uk/OBCA.php
ISIS 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 http://www.i-sis.org.uk/full/OBCAFull.php.
Details here http://www.i-sis.org.uk/membership.php

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];
http://www.i-sis.org.uk/isisnews/sis16.php
"Organic production works", SiS 25 [2]).
http://www.i-sis.org.uk/isisnews/sis25.php

Researchers led by David Pimentel, 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).

[Plain text versions of this press release do not contain table 1,
please see http://www.i-sis.org.uk/OBCA.php for this information]

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 Pimentel 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]).






  • [Livingontheland] Organic Yields on Par with Conventional and Ahead During Drought Years, Tradingpost, 09/16/2005

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