Organic Agriculture Enters Mainstream

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12 Sep 2005 15:04:21 -0000

Organic Agriculture Enters Mainstream

press-release

 

 

The Institute of Science in Society Science Society

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press-release ISIS Director m.w.ho

 

This article can be found on the I-SIS website at

http://www.i-sis.org.uk/OBCA.php

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ISIS Press Release 12/09/05

 

Organic Agriculture Enters Mainstream

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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 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).

 

 

[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 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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