Healthy soil and sustainable growing

["TradingPostPaul" <tradingpost@riseup.net>]

"There is clearly a lot of scope in reducing transport, processing and
packaging, as well as storage in our food system, all of which argue
strongly in favour of food production for local consumption in addition to
adopting organic, sustainable agricultural practices. "

http://www.i-sis.org.uk/mitigatingClimateChange.php
ISIS Press Release 05/12/07

Mitigating Climate Change through Organic Agriculture

There is much scope for mitigating climate change through sustainable
agriculture and localising the food supply chain. Dr. Mae-Wan Ho and
Lim Li Ching

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

Modern industrial agriculture of the “Green Revolution” contributes a
great deal to climate change. It is the main source of the potent
greenhouse gases nitrous oxide and methane; it is heavily dependent
on the use of fossil fuels, and contributes to the loss of soil
carbon to the atmosphere [1] (Feeding the World under Climate Change,
SiS 24), especially through deforestation to make more land available
for crops and plantations. Deforestation is predicted to accelerate
as bio-energy crops are competing for land with food crops [2]
(Biofuels: Biodevastation, Hunger & False Carbon Credits, SiS 33).
But what makes our food system really unsustainable is the
predominance of the globalised commodity trade that has resulted in
the integration of the food supply chain and its concentration in the
hands of a few transnational corporations. This greatly increases the
carbon footprint and energy intensity of our food consumption, and at
tremendous social and other environmental costs. A UK government
report on food miles estimated the direct social, environmental, and
economic costs of food transport at over £9 billion each year, which
is 34 percent of the £26.2 billion food and drinks market in the UK
[3] (Food Miles and Sustainability, SiS 28).

Consequently, there is much scope for mitigating climate change and
reversing the damages through making agriculture and the food system
as a whole sustainable, and this is corroborated by substantial
scientific and empirical evidence (see below). It is therefore rather
astonishing that the Intergovernmental Panel on Climate Change should
fail to mention organic agriculture as a means of mitigating climate
change in its latest 2007 report [4]; nor does it mention localising
food systems and reducing long distance food transport [5].


Reducing direct and indirect energy use in agriculture

There is no doubt that organic, sustainable agricultural practices
can provide synergistic benefits that include mitigating climate
change. As stated in the 2002 report of the United Nations Food and
Agriculture Organisation (FAO), organic agriculture enables
ecosystems to better adjust to the effects of climate change and has
major potential for reducing agricultural greenhouse gas emissions [6].

The FAO report found that, “Organic agriculture performs better than
conventional agriculture on a per hectare scale, both with respect to
direct energy consumption (fuel and oil) and indirect consumption
(synthetic fertilizers and pesticides)”, with high efficiency of
energy use.

Since 1999, the Rodale Institute’s long-term trials in the United
States have reported that energy use in the conventional system was
200 percent higher than in either of two organic systems - one with
animal manure and green manure, the other with green manure only -
with very little differences in yields [7]. Research in Finland
showed that while organic farming used more machine hours than
conventional farming, total energy consumption was still lowest in
organic systems [8]; that was because in conventional systems, more
than half of total energy consumed in rye production was spent on the
manufacture of pesticides.

Organic agriculture was more energy efficient than conventional
agriculture in apple production systems [9, 10]. Studies in Denmark
compared organic and conventional farming for milk and barley grain
production [11]. The energy used per kilogram of milk produced was
lower in the organic than in the conventional dairy farm, and it also
took 35 percent less energy to grow a hectare of organic spring
barley than conventional spring barley. However, organic yield was
lower, so energy used per kg barley was only marginally less for the
organic than for the conventional.

The total energy used in agriculture accounts for about 2.7 percent
of UK’s national energy use [12], and about 1.8 percent of national
greenhouse gas emissions [13] based on figures for 2002, the latest
year for which estimates are available. Most of the energy input
(76.2 percent) is indirect, and comes from the energy spent to
manufacture and transport fertilizers, pesticides, farm machinery,
animal feed and drugs. The remaining 23.8 percent is used directly on
the farm for driving tractors and combine harvesters, crop drying,
heating and lighting glasshouses, heating and ventilating factory
farms for pigs and chickens.

Nitrogen fertiliser is the single most energy intensive input,
accounting for 53.7 percent of the total energy use. It takes 35.3 MJ
of energy on average to produce each kg of N in fertilizers [14]. UK
farmers use about 1 million tonnes of N fertilisers each year.
Organic farming is more energy efficient mainly because it does not
use chemical fertilizers [15].

The Soil Association found that organic farming in the UK is overall
about 26 percent more efficient in energy use per tonne of produce
than conventional farming, excluding tomatoes grown in heated
greenhouses [15]. The savings differ for different crops and sectors,
being the greatest in the milk and beef, which use respectively 28
and 41 percent less energy than their conventional counterparts.

Amid rapidly rising oil prices in 2006, with farmers across the
country deeply worried over the consequent increase in their
production costs, David Pimentel at Cornell University, New York, in
the United States returned to his favourite theme [16]: organic
agriculture can reduce farmers’ dependence on energy and increase the
efficiency of energy use per unit of production, basing his analysis
on new data.

On farms throughout the developed world, considerable fossil energy
is invested in agricultural production. On average in the US, about 2
units of fossil fuel energy is invested to harvest a unit of energy
in crop. That means the US uses more than twice the amount of fossil
energy than the solar energy captured by all the plants, which is
ultimately why its agriculture cannot possibly sustain anything like
the biofuel production promoted by George W. Bush [17] (Biofuels for
Oil Addicts, SiS 30).

Corn is a high-yield crop and delivers more kilocalories of energy in
the harvested grain per kilocalorie of fossil energy invested than
any other major crop [16].  `

Counting all energy inputs in fossil fuel equivalents in an organic
corn system, the output over input ratio was 5.79 (i.e., you get 5.79
units of corn energy for every unit of energy you spent), compared to
3.99 in the conventional system. The organic system collected 180
percent more solar energy than the conventional. There was also a
total energy input reduction of 31 percent, or 64 gallons fossil fuel
saving per hectare. If 10 percent of all US corn were grown
organically, the nation would save approximately 200 million gallons
of oil equivalents.

Organic soybean yielded 3.84 kilocalories of food energy per kilo of
fossil energy invested, compared to 3.19 in the conventional system
and the energy input was 17 percent lower. Organic beef grass-fed
system required 50 percent less fossil fuel energy than conventional
grain-fed beef.

Lower greenhouse gas emissions

Globally, agriculture is estimated to contribute directly 11 percent
to total greenhouse gas emissions (2005 figures from
Intergovernmental Panel on Climate Change) [18]. The total emissions
were 6.1Gt CO2e, made up almost entirely of CH4 (3.3 Gt ) and N2O
(2.8Gt). The contributions will differ from one country to another,
especially between countries in the industrial North compared with
countries whose economies are predominantly agricultural.

In the United States, agriculture contributes 7.4 percent of the
national greenhouse gas emissions [19]. Livestock enteric
fermentation and manure management account for 21 percent and 8
percent respectively of the national methane emissions. Agricultural
soil management, such as fertilizer application and other cropping
practices, accounts for 78 percent of the nitrous oxide emitted.

In the UK, agriculture is estimated to contribute directly 7.4
percent to the nation’s greenhouse gas emissions, with fertilizer
manufacture contributing a further 1 percent [20], and is comprised
entirely of methane at 37.5 percent of national total [21] and
nitrous oxide at around 95 percent of the national total [22].
Enteric fermentation is responsible for 86 percent of the methane
contribution from agriculture, the rest from manure; while nitrous
oxide emissions are dominated by synthetic fertilizer application (28
percent) and leaching of fertilizer nitrogen and applied animal
manures to ground and surface water (27 percent) [23].

The FAO estimated that organic agriculture is likely to emit less
nitrous oxide (N2O) [6]. This is due to lower N inputs, less N from
organic manure from lower livestock densities; higher C/N ratios of
applied organic manure giving less readily available mineral N in the
soil as a source of denitrification; and efficient uptake of mobile N
in soils by using cover crops.

Greenhouse gas emissions were calculated to be 48-66 percent lower
per hectare in organic farming systems in Europe [24], and were
attributed to no input of chemical N fertilizers, less use of high
energy consuming feedstuffs, low input of P, K mineral fertilizers,
and elimination of pesticides, as characteristic of organic agriculture.

Many experiments have found reduced leaching of nitrates from organic
soils into ground and surface waters, which are a major source of
nitrous oxide (see above). A study reported in 2006 also found
reduced emissions of nitrous oxide from soils after fertilizer
application in the fall, and more active denitrifying in organic
soils, which turns nitrates into benign N2 instead of nitrous oxide
and other nitrogen oxides [25] (see Cleaner Healthier Environment for
All, SiS 37).

It is also possible that moving away from a grain-fed to a
predominantly grass-fed organic diet may reduce the level of methane
generated, although this has yet to be empirically tested. Mike
Abberton, a scientist at the Institute of Grassland and Environmental
Research in Aberystwyth, has pointed to rye grass bred to have high
sugar levels, white clover and birdsfoot trefoil as alternative diets
for livestock that could reduce the quantity of methane produced  [26].

A study in New Zealand had suggested that methane output of sheep on
the changed diet could be 50 percent lower. The small UK study did
not achieve this level of reduction, but found nevertheless that
“significant quantities” of methane could be prevented from getting
into the atmosphere. Growing clover and birdfoot trefoil could help
naturally fix nitrogen in organic soil as well as reduce livestock
methane.

Greater carbon sequestration

Soils are an important sink for atmospheric CO2, but this sink has
been increasingly depleted by conventional agricultural land use, and
especially by turning tropical forests into agricultural land. The
Stern Review on the Economics of Climate Change commissioned by the
UK Treasury and published in 2007 [27] highlights the fact that 18
percent of the global greenhouse gas emissions (2000 estimate) comes
from deforestation, and that putting a stop to deforestation is by
far the most cost-effective way to mitigate climate change, for as
little as $1/ t CO2 [28] (see The Economics of Climate Change, SiS
33). There is also much scope for converting existing plantations to
sustainable agroforestry and to encourage the best harvesting
practices and multiple uses of forest plantations [29, 30] (Multiple
Uses of Forests, Sustainable Multi-cultures for Asia & Europe, SiS 26)

Sustainable agriculture helps to counteract climate change by
restoring soil organic matter content as well as reducing soil
erosion and improving soil physical structure. Organic soils also
have better water-holding capacity, which explains why organic
production is much more resistant to climate extremes such as
droughts and floods [31] (Organic Agriculture Enters Mainstream,
Organic Yields on Par with Conventional & Ahead during Drought Years,
SiS 28), and water conservation and management through agriculture
will be an increasingly important part of mitigating climate change.

The evidence for increased carbon sequestration in organic soils
seems clear. Organic matter is restored through the addition of
manures, compost, mulches and cover crops.

The Sustainable Agriculture Farming Systems (SAFS) Project at
University of California Davis in the United States [32] found that
organic carbon content of the soil increased in both organic and low-
input systems compared with conventional systems, with larger pools
of stored nutrients. Similarly, a study of 20 commercial farms in
California found that organic fields had 28 percent more organic
carbon [33]. This was also true in the Rodale Institute trials, where
soil carbon levels had increased in the two organic systems after 15
years, but not in the conventional system [34]. After 22 years, the
organic farming systems averaged 30 percent higher in organic matter
in the soil than the conventional systems [31].

In the longest running agricultural trials on record of more than 160
years, the Broadbalk experiment at Rothamsted Experimental Station,
manure-fertilized farming systems were compared with chemical-
fertilized farming systems [35]. The manure fertilized systems of oat
and forage maize consistently out yielded all the chemically
fertilized systems. Soil organic carbon showed an impressive increase
from a baseline of just over 0.1 percent N (a marker for organic
carbon) at the start of the experiment in 1843 to more than double at
0.28 percent in 2000; whereas those in the unfertilized or chemical-
fertilized plots had hardly changed in the same period. There was
also more than double the microbial biomass in the manure-fertilized
soil compared with the chemical-fertilized soils.

As Pimentel stated [16]: “..high level of soil organic matter in
organic systems is directly related to the high energy efficiencies
observed in organic farming systems; organic matter improves water
infiltration and thus reduces soil erosion from surface runoff, and
it also diversifies soil-food webs and helps cycle more nitrogen from
biological sources within the soil.”

Reducing energy and greenhouse gas emissions in sustainable food systems

Agriculture accounts only for a small fraction of the energy
consumption and greenhouse gas emissions of the entire food system.

Pimentel [16] estimated that the US food system uses about 19 percent
of the nation’s total fossil fuel energy, 7 percent for farm
production, 7 percent for processing and packaging and 5 percent for
distribution and preparation. This is already an underestimate, as it
does not include energy embodied in buildings and infrastructure,
energy in food wasted, nor in treating food wastes and processing and
packaging waste, which would be necessary in a full life cycle
accounting.

Similarly, when the emissions from the transport, distribution,
storage, and processing of food are added on, the UK food system is
responsible for at least 18.4 percent of the national greenhouse gas
emissions [36], again, not counting buildings and infrastructure
involved in food distribution, nor wastes and waste treatments.

Here’s an estimate of the greenhouse gas emissions from eating based
on a full life cycle accounting, from farm to plate to waste, from
data supplied by CITEPA (Centre Interprofessionnel Technique d’Eudes
de la Pollution Atmosphérique) for France [37].

Greenhouse gas emissions from eating (France)

Agriculture direct emissions
42.0 Mt C
Fertilizers (French fertilizer industry only, more than half imported.)
0.8 Mt C
Road transport goods (within France only, not counting export/import)
4.0 Mt C
Road transport people
1.0 Mt C
Truck manufacture & diesel
0.8 Mt C
Store heating (20% national total)
0.4 Mt C
Electricity (nuclear energy in France, multiply by 5 elsewhere)
0.7 Mt C
Packaging
1.5 Mt C
End of life of packaging (overall emissions of waste 4 Mt)
1.0 Mt C
Total
52.0 Mt C
National French emission
171.0 MtC
Share linked to food system
30.4%
The figure of 30.4 percent is still an underestimate, because it
leaves out emissions from the fertilizers imported, from pesticides,
and transport associated with import/export of food. Also, the
emission of electricity from established nuclear power stations in
France is one-fifth of typical non-nuclear sources. Others may argue
that one needs to include infrastructure costs, so that buildings and
roads, as well as the building of nuclear power stations need to be
accounted for.

The tale of a bottle of ketchup

A hint of how food transport, processing and packaging contribute to
the energy and greenhouse gas budgets of the food system can be
gleaned by the life-cycle analysis of a typical bottle of ketchup.

The Swedish Institute for Food and Biotechnology did a life-cycle
analysis of tomato ketchup, to work out the energy efficiency and
impacts, including the environmental effects of global warming, ozone
depletion, acidification, eutrophication, photo-oxidant formation,
human toxicity and ecotoxicity [38].

The product studied is one of the most common brands of tomato
ketchup sold in Sweden, marketed in 1 kg red plastic bottles. Tomato
is cultivated and processed into tomato paste in Italy, packaged and
transported to Sweden with other ingredients to make tomato ketchup.

The aseptic bags used to package the tomato paste were produced in
the Netherlands and transported to Italy; the bagged tomato paste was
placed in steel barrels, and moved to Sweden. The five-layered red
bottles were either made in the UK or Sweden with materials from
Japan, Italy, Belgium, the USA and Denmark. The polypropylene screw
cap of the bottle and plug were produced in Denmark and transported
to Sweden. Additional low-density polyethylene shrink-film and
corrugated cardboard were used to distribute the final product. Other
ingredients such as sugar, vinegar, spices and salt were also
imported. The bottled product was then shipped through the wholesale
retail chain to shops, and bought by households, where it is stored
refrigerated from one month to a year. The disposal of waste package,
and the treatment of wastewater for the production of ketchup and
sugar solution (from beet sugar) were also included in the accounting.

The accounting of the whole system was split up into six subsystems:
agriculture, processing, packaging, transport, shopping and household.

There are still many things left out, so the accounting is nowhere
near complete: the production of capital goods (machinery and
building), the production of citric acid, the wholesale dealer,
transport from wholesaler to the retailer, and the retailer.
Likewise, for the plastic bottle, ingredients such as adhesive,
ethylenevinylalcohol, pigment, labels, glue and ink were omitted.
For the household, leakage of refrigerants was left out. In
agriculture, the assimilation of carbon dioxide by the crops was not
taken into consideration, neither was leakage of nutrients and gas
emissions such as ammonia and nitrous oxide from the fields. No
account was taken of pesticides.

We estimated the energy use and carbon emissions for each of the six
subsystems from the diagrams provided in the research paper, and have
taken the energy content of tomato ketchup from another brand to
present their data in another way (Tables 1 and 2), taking the
minimum values of energy and emissions costs.

Table 1. Energy Accounting for 1 kg Tomato Ketchup

Subsystem
Energy GJ

Agriculture
1.3
Processing
7.2
Packaging
7.8 (without waste incineration)

6.0 (with waste incineration)
Transport
1.0
Shopping
1.2
Household
1.4 (refrigeration for one month)

14.8 (refrigeration for one year)
Total (minimum)
18.1
Energy in 1 kg tomato paste
0.00432
Energy use per GJ tomato paste
4 190

Table 2. Carbon Dioxide Accounting for 1 kg Tomato Ketchup

Subsystem
Carbon dioxide equivalent kg

Agriculture
190
Processing
500
Packaging
1 275 (without incineration)

2 315 (with incineration)
Transport
130
Shopping
195
Household
0
Total (minimum)
2 290
As can be seen, it takes at least 4190 units of energy to deliver 1
unit of ketchup energy to our dinner table, with at least 2 290 kg of
carbon dioxide emissions per kg ketchup.

Packaging and food processing were the hotspots for many impacts. But
at least part of the packaging is due to the necessity for long
distance transport. Within the household, the length of time stored
in the refrigerator was critical.

For eutrophication, the agricultural system is an obvious hotspot.
For nitrous oxide emissions, transportation is another hotspot. For
toxicity, the agriculture, food processing and packaging were
hotspots, due to emissions of sulphur dioxide, nitrogen oxides and
carbon monoxide; also heavy metals, phenol or crude oil. If leakage
of pesticides, their intermediates and breakdown products had been
considered, then agriculture would have been an even worse
toxicological hotspot.

As regards the capital costs for tomato cultivation omitted from the
study, literature from France gave a value of 0.180GJ/kg. As regards
the wholesale and retail step left out of the study, literature data
indicate 0.00143GJ/kg beer for storage at wholesale trader in
Switzerland and 0.00166GJ/kg bread in the Netherlands.

There is clearly a lot of scope in reducing transport, processing and
packaging, as well as storage in our food system, all of which argue
strongly in favour of food production for local consumption in
addition to adopting organic, sustainable agricultural practices. An
integrated organic food and energy farm that turns wastes into
resources can be the ideal solution to reducing greenhouse gas
emissions at source, decreasing environmental pollution, reducing
transport, and increasing energy efficiencies to the point of not
having to use fossil fuels altogether [39] (How to Beat Climate
Change & Be Food and Energy Rich - Dream Farm 2, ISIS Report).