A comparison of the energetic output of Organic and Conventional farming

systems and implications for resilience

S. Norton1, H. Moller1, J. Benge2 D. Lucock3 and J. Manhire3

1. Centre for the Study of Agriculture, Food, and Environment, University of Otago, PO box 56, Dunedin 9054, New Zealand2. Zespri, Mount Maunganui, New Zealand3. The Agribusiness Group, Christchurch, New ZealandCorrespondence: Solis.norton@otago.ac.nz

Introduction

• Western agriculture is continually intensifying

– Worldwide, agriculture accounts for 10-12% of emissions

– Increased by 17% between 1990 and 2005

– In the decade to 2002 fertiliser use up 160-240% in NZ (PCE, 2004)

• IPCC and PCE reports call for redesign of agriculture toward

resilience and genuine sustainability

• Humans will number 9b by ~2043, up ~33% on today

• Aim: reconcile transformative resilience and growth?

Materials and methods

ARGOS (www.argos.org.nz)

• Otago, Lincoln, Agribusiness Group

• Longitudinal trans-disciplinary study (2002 - 2009)

• Environmental, social, & economic sustainability of NZ ag

• Management: Organic, Integrated (IM), Conventional

• Production system: kiwifruit, sheep & beef, dairy

• 105 participants in ‘clusters’

Materials and methods

Kiwifruit

• 12 Organic Green, 12 Conventional Green, 12 IM Gold

• Production data for 2002/03 – 2007/08

• Energetic output per hectare (GJ/canopy hectare)

• Estimate energy content of kiwifruit by literature and web

review and bootstrapping methods

• Economic Orchard Surplus data for 2002/03 – 2006/07

Materials and methods

Sheep and beef

• 12 Organic, 12 IM, 12 Conventional• Energy in live weight leaving farm

– Data for 2006/07– Energy estimated at 8.5 MJ/kg live weight based on literature

review– Per effective farm hectare– Includes lambs, older sheep, and beef

• Economic Farm Surplus data for 2001/02 – 2007/08

Dairy

• 12 Conventional and 12 Organic

• Transition for Organic producers was 2003/04

• Energetic output in milk

• 1 kg of milksolids contains 38 MJ energy (Wells, 2001)

• Milk production data for 2003/04 – 2007/08

• Reported as MJ/effective hectare

Materials and methods

Statistical methods

• Distribution of each variable checked and log transformed if necessary

• Generalised Linear Mixed Effects models and MCMC methods for confidence intervals

• Control for variation between clusters (climatic and environmental effects of participant location)

• Season*management interaction for dairy to quantify seasonal productivity since transition

Materials and methods

Kiwifruit

Scale Group Estimate % of IM Green P<0.05Energy/ha (GJ) IM Green 56 Reference

Organic Green 40 74 *IM Gold 57 102 n/s

Economic Surplus IM Green 1201 Reference($/canopy ha) Organic Green 4734 394 n/s

IM Gold -15 1 n/s

Output on Organic orchards only 74% of IM Green

Economic Surplus highly variable within orchard

Sheep & beef

Scale Group Estimate % of Conventional

P<0.05

Energy/ha (GJ) Conventional 34 ReferenceOrganic 24 71 n/sIM 41 121 n/s

Economic surplus Conventional 58 Reference($/eff ha) Organic -27 147 n/s

IM 49 84 n/s

Organic farm output 71% of conventional, but not sig. different

Economic Surplus was highly variable within farm

Dairy production

Scale Group Estimate % of Conventional

P<0.05

Energy/ha (GJ) Conventional 39 ReferenceTransition organic 29 74 *

Energetic output by Organic herds was 74% of the Conventional herds, significantly lower

Trend of declining output per ha across Production types: KF=56, dairy=39, S&B=34

Annual dairy production

Management system

Ene

rgy

prod

uced

in m

ilk (

MJ/

ha)

010

000

2000

030

000

4000

050

000

Conv Trans Conv Trans Conv Trans Conv Trans Conv Trans

Ref P=0.13 P=0.02 P<0.00 P<0.00 P<0.00

2003/04 2004/05 2005/06 2006/07 2007/08

Discussion

• Energetic output differences were surprisingly

consistent

– 74% for dairy and KF, 71% of S&B

– Clearly significant differences in 2 of 3 production system

• Economic variability masks Organic (un?)profitability

• Diary trend following transition suggests management

not farmers causes drop in output

• Next steps: cropping, fert, cull cows, inputs…

Discussion

• Our results and the literature

– Organic dairy production 78-90% of Conv (Sundberg et al. (2009)– Organic feedlot beef live weight gain 84% of Conv and lower

carcass weights (Fernandez et al. 1999) – Organic field tomatos inTunisia and capsicum in Himalayas both

60% of Conv (Riahi et al. 2009, Gopinath et al. 2009)– Organic cotton 66% of Conv, 6 yr study in California (Swezey et

al. 2007)– Organic small scale wheat production 71% of Conv (Berardi

1978)– Organic apples 66% of Conv, 10yr study (Peck et al. 2006)

Trend clearly evident (~25%) but not entirely consistent

Discussion

• Resilience in coming decades

– Peak Oil– Peaks in other inputs eg phosphate– Regulatory impacts of climate change (IPCC)– Water constraints– Physical impacts of climate change– PCE

• Management shift toward organic end of spectrum• Lower output per hectare as a result?

Discussion

Resilience and implications for economic development

– Would NZ export income decline? Lower output delivered to niche market premiums? Do we have a food crisis? Social responsibility?

– World food production up by 30% by 2040 to keep pace with predicted population growth

– Critical research and action is urgently required to safeguard global food supply and NZ’s economic prosperity in coming decades