[permaculture] Fwd: [pfaf] Can stockless organic systems really be sustainable?

Rain Tenaqiya raincascadia at yahoo.com
Thu Jun 10 14:12:01 EDT 2004

Richard Morris <webmaster at pfaf.org> wrote:To: "pfaf at yahoogroups.com" 

From: Richard Morris 
Date: Sun, 06 Jun 2004 22:22:41 +0100
Subject: [pfaf] Can stockless organic systems really be sustainable?

A very interesting article on stockless (i.e vegan)

Found on the veganorganic mailing list
the mailing list of the Vegan Organic Trust
who are one of the main voices for vegan organic growing.

Can stockless organic systems really be sustainable?

Miles Gibson

Organic Farming Diploma
Scottish Agriculture College
Year 1

Soils and Nutrient Cycling


The Bruntland report (WCED 1987) defined sustainable practice as that
which 'meets the needs and aspirations of the present without
compromising the ability of future generations to meet their own needs'.
This is a commonly used but very broad definition that can encompass
environmental, social and economic factors on anything from an
individual farm-scale level to a global one. It leaves a great deal of
room for debate and speculation, for example how to weigh the economic
aspirations of a developing country against long term environmental well
being. It is not suprising that Rigby and Woodhouse (2001) report that
there is no consensus on sustainability's 'precise or operational
meaning'. For the purposes of this essay therefore I will now briefly
outline the elements of sustainability that I will be focusing on
without any claim to be comprehensively covering every aspect and nuance
of this multifaceted concept.

In this essay I will be focusing on soil health, particularly nutrient
budgeting; on what is practically sustainable which generally comes down
to economics; and more briefly on environmental and social issues on a
local and global level. All these aspects of sustainability are
interconnected but for the sake of structure I will attempt to deal with
them separately. My main concern is for what is operationally possible
and organically principled on a farm scale level in this country. Which
is also the arena in which I think it is possible to talk with the least
speculation. The discussion will involve some comparison with livestock
and mixed systems but the predominant focus will be upon the viability
of stockless systems.

Setting the scene

For founders of the organic movement such as Lady Eve Balfour livestock
were an integral part of any sustainable organic system. Without their
manures a vital part of the nutrient cycle would be lost. To this day
the majority of organic farming in UK is on mixed or livestock units in
central and western areas, mixed units being closest to the original
self-sufficient ideal. On mixed farms the grass-clover ley is expected
to accumulate sufficient nitrogen for subsequent arable crops, while
also supporting animal production. Grass clover leys typically occupy at
least 50% of the mixed farm and the manure generated can be used to move
nutrients around the farm within the rotation (Philipps, L 2001). The
amount of ley required in such a rotation presents a challenge to
stockless organic systems and indeed in arable eastern areas of the UK
conversion to organic has been far less prevalent. Some stockless
systems however have been developed using a one year nitrogen fixing
green manure crop designated as set-aside within the rotation (Watson et
al 2000). There are also a few pioneers such as the Vegan Organic Trust
and Iain Tolhurst who maintain that through the careful management of
rotations and green manures a closed system is achievable that scores
more highly in terms of sustainability than any of the alternative

Soil health and nutrient budgeting

Achieving a balance between inputs and outputs of nutrients in a farming
system is vital both for short-term productivity and long term
sustainability (Watson et al 2000). In stockless farming green manures
are at the heart of nutrient cycling. They take nitrogen (N) from the
air and via soil bacteria recycle it so that it can be used as a source
of fertility. The sustainability of this process has been a key focus of
the research into stockless farming that has been carried out.

In 1987 the Elm farm research centre (EFRC) established a stockless
trial which ran until 1998. They compared 3 different 4 year rotations
all of which used a one year red clover manure for fertility building
(Philipps, L 2001). Rock phosphate was also applied to the maximum rate
allowed by Soil Association during the green manure phase of the
rotation. The red clover green manures accumulated approximately 300kg
N/ha above ground which was considered enough to support the estimated
nitrogen offtake. An N deficit recorded on a similar stockless trial
conducted by ADAS at the Terrington Research Farm in Norfolk was
attributed to poor germination and establishment of the red clover, and
not an inherent failing in the system. The timing of incorporation and
the N demand of subsequent crops is also considered critical to minimise
N losses (Watson et al 2000)

In the EFRC trial Phosphorous (P) needs were met by the rock phosphate,
and levels of Potassium (K) were not affected. This led to the
conclusion that soils with a clay content greater than 20% seem to be
able to derive sufficient K from mineralization to sustain crop yields,
although it was acknowledged that more research on sustainability for
different soil types was needed. At Terrington although K was in
deficit, there was no measurable change in available K or P. This may be
because the less intensive nature of production mean lower soil P and K
are acceptable (Fortune et al 2001)

A potential problem was the significant decline that was observed in
levels of Soil Organic Matter (SOM) by EFRC, particularly in the first 4
years, although this may be explained by the change from grass to arable
production. Any conventional system would also be likely to experience a
similar drop in such circumstances. It should also be noted that changes
in setaside regulations have allowed organic farmers to use setaside as
a means of fertility building for up to 2 years, as opposed to the 1
used in these trials this inevitably benefits SOM levels.

On the subject of SOM and green manures it is worth mentioning recent
work done at the Rodale institute (Drinkwater et al 1998) which showed
that the rate of accumulation of SOM when farmyard manure was used as
fertiliser was double that of when leguminous green manures was used.
This seems to point to an advantage that livestock or mixed systems have
but more research needs to be done on the relationship between organic
matter content of the soil and soil structure and crop yields to really
prove this.

A slightly different approach to balancing the nutrient budget and
maintaining soil health has been adopted by Iain Tolhurst in his
stockless field vegetable and market garden enterprise in south
Oxfordshire. He points to the importance of his rotations and operates
far longer ones, 7 years for field vegetables and 9 years in his market
garden. Regular soil analysis has shown steadily improving fertility
particularly phosphate and potash due to the deep-rooting foraging of
the legumes. The soil fauna has improved as has health of the more than
70 crops grown. (Tolhurst 2004). Tolhurst is a powerful advocate of
under sown green manure (ugm) as a way of reducing time needed in the
fertility-building phase. Ugm will not only add nitrogen and organic
matter to the soil but even more importantly according to Tolhurst
(2003) it ensures the soil is covered prior to the winter period when
the loss of nutrients to leaching is even greater than the nutrient loss
in crop off-take. The vital emphasis is on making sure that the more
modest level of inputs is balanced by reducing outputs. Deep rooting
green manure also helps to recycle nutrients that may have been lost to
lower soil levels during previous cropping.

In terms of general soil health deep rooting of green manures also
improves soil structure. Their cover also benefits earthworm and soil
fauna populations. Tolhurst does stress however that the Ugm should not
be seen as way of eliminating the need for a fertility break in the
rotation as a resting period when the soil is not being cultivated at
all is the best possible condition for earthworms to flourish.

Economic and Management considerations

EFRC stockless trials reported that over an 11 year period yields have
been maintained, there have been insignificant disease levels and due to
clover allowance for organic fields in setaside, there has been a
healthy financial return. A critical factor in determining yield has
been crop establishment. Similarly the ADAS research recorded impressive
potato and cereal yields with good price premiums and lower variable
costs giving favourable gross margins. This held true when projected to
a national farm size and allowance was made for the Set Aside and Arable
Area Payments, although it was noted that price premiums for organic
produce cannot always be relied on (Watson et al 2000). This projection
is also open to question on lighter soils where organic cereal yield is
less impressive (Cormack 1999). Although the already mentioned new set
aside regulations that make a 2 year ley viable would boost fertility
and therefore yield.

The issue of ratio of fertility building to cash crop may also be
addressed by careful planning of rotations and under sown green manures
as has been done by Iain Tolhurst. He currently has cash crops at a
level of 70% while maintaining fertility levels and is running an
economically viable operation (Tolhurst 2004). Although he is aware with
some crops ugm may compete for nutrient and moisture with the main crop.
He believes it is acceptable to take a lower yield in order to build
adequate fertility for future cropping (Tolhurst 2003). He also points
to the greater costs involved in keeping livestock and claims that at a
small farm scale it is mixed and livestock systems that are not
economically viable.

The management issues in stockless systems centre mainly on weeds and
pests. The EFRC trial reported no sign of weeds, pests and disease
increase (Bulson 1996) and noted that some crop sequences were
particularly effective in suppressing weeds. A build up of perennial
weeds was reported in the ADAS and CWS trials (Leake 1999) however.

Iain Tolhurst sees as vital the timely establishment of ugm to smother
weeds, although concedes that a high degree of management is required as
there is only a narrow window of opportunity for pre-sowing weed control
and subsequent sowing of green manure (Tolhurst 2003) He also points to
the benefits of green cover between rows that can confuse some pests
while also attracting beneficial insects, although he does stress the
need to chose crops carefully in order to avoid slug problems. Jean Paul
Cortens (Cortens 2004) of Roxbury farm adds to the debate by describing
how insects will migrate to cash crops when cover crops are cut and many
diseases and pests like aphids increase when too much raw fertility is
applied. His suggested solution is to never mow all cover crops at once,
and to have another crop available for insects to migrate to.

Environmental and social considerations

On a global level there have been substantial losses in SOM during the
last 100 years, this is associated with changing patterns of land use
driven by population increase (Rees R 2001). There has never been a
greater pressure on the world's ecosystems to provide for human needs,
and there are many who believe that the answer to this challenge is to
be found in a significant reduction in livestock farming and an increase
in stockless systems. Currently the combined weight of cattle in the
world exceeds that of human beings to support this ¼ of earth's surface
is used as livestock pasture. The destruction of Brazilian rainforest
has been driven by the desire to grow soya for animal feed (Sams2003).
It has also been estimated that the only way Europe could feed itself
organically would be for the proportion of grain legumes grown to be
increased at the expense of livestock production (Stockdale, E et al
2000). European livestock farming currently relies on feed grown in
developing countries which ties up resources that could be used to meet
their own domestic food needs. It is highly questionable whether this is
a sustainable way of feeding the world's population.

This imbalance also exists domestically, where more than 65% of cereal
crops in England go to feed animals on top of the huge additional
quantity imported from all over world. Despite the organic ideal of a
closed system all livestock systems and the vast majority of mixed
systems buy in feed or bedding from elsewhere thereby depriving somebody
else of their fertility. This compares unfavourably in terms of
sustainability with stockless systems such as Iain Tolhurst's vegetable
farm that operates a self-sufficient nutrient budget. There are also
many more environmental and social dangers such as pollution and
zoonotic diseases from using farm yard manure and slurry as fertiliser
than green manures.

Concluding remarks

Although stockless organic farming remains relatively untried and
unresearched in this country, what has been done so far looks
favourable. Alastair Leake of C.W.S Agriculture in a review of stockless
experiments at EFRC, ADAS and CWS concluded "all arable organic farming
is economically viable and technically feasible" (2001). There are also
pioneering techniques being developed through practice by the likes of
Iain Tolhurst with his long rotations, use of ugm and balancing of the
nutrient budget by compensating for less input by ensuring there are
less losses. It seems that these ideas are generating momentum in the UK
with the Vegan Organic Trust set to launch the first ever stock free
standards under the wing of the Soil Association. On a global scale it
is hard to disagree with those who argue that a significant increase in
stockless systems would be the most economical, sustainable and least
harmful use of the Earth's increasingly pressured food producing
resources. Evidence also suggests that the less meat rich diet this
would entail might even see us all sustained in good health a little
longer with lower risk of heart disease, obesity and cancer!


Bulson H (1996) Is there life without livestock? New Farmer and Grower,
Winter 1996.

Cormack W (1999) Testing a stockless arable rotation on a fertile soil.
In Designing and Testing crop rotations for Organic Farming pp 115-123.
Eds Olesen J et al. DARCOF Report No 1

Cortens J (2004) Fertility a management at Roxbury Farm. A case study.
SAC Blackboard

Drinkwater L et al (1998) Legume-based cropping systems have reduced
carbon and nitrogen losses. Nature, vol. 396, 19 Nov. 1998

Fortune, S et al (2001) N, P, K Budgets for some UK Organic Farming
Systems Implications for Stability. In Soil Organic Matter and
Sustainability pp 286-293. CABI Wallingford

Leake A (1999) A report of the results of CWS Agriculture's organic
farming experiments 1989-1996. J. Roy. Agric. Soc. Eng, vol. 160, 1999

Leake A (2001) Performance of arable organic farming: a UK experience.

Philipps, L (2001) The Effects of All-arable Organic Rotations on Soil
Organic Matter Levels and the Phosphorous and Potassium status over the
Period 1987-1998. In Sustainable Management of Soil Organic Matter. CABI

Tolhurst I (2004) Vegetable Farm. Organic Gardening January 2004

Tolhurst I (2003) Under Sowing Green Manures in Vegetable Crops. VON

Rees R Ed (2001) Sustainable Management of Soil Organic Matter. CABI

Rigby D and Woodhouse P (2001) Constructing a farm level indicator of
sustainable agricultural practice. Ecological Economics 2001, Vol 39, No
3, pp 463-478.

Sams C (2003) The Little Food Book. Alastair Sawday Publishing

Watson C et al (2000) Agronomic and Environmental implications of
stocked and stockless organic rotations. Aspects of Applied Biology 62,

WCED (1987) The Bruntland Report. Our Common Future. OUP

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