Can organic farming save the world?

1. Can organic farming save the world? Royal Society-Wolfson Professor of Soils & Global Change Institute of Biological & Environmental Sciences, School of Biological Sciences, University of Aberdeen, Scotland, UK E-mail: pete.smith@abdn.ac.uk Pete Smith Transition: Food and Farming in 21st Century Britain, Soil Association National Conference,Bristol, 18-19th November 2008

2. The big challenges for organic farming • Can organic farming maintain productivity to feed 9 Billion people, without spreading onto more land? • Is organic farming compatible with reduced livestock numbers / consumption? • Can organic residues provide enough reactive N to fertilise crops sufficiently to feed 9 Billion people?

3. The role of organic agriculture – potential positives • Most practices improve soil C sequestration • Reduce need for mineral N fertiliser (but not eradicate it?) • Reduce fossil fuel cost of manufacturing mineral N fertiliser • Keep nutrient cycles tightly coupled • Improve soils fertility, biodiversity etc.

4. The role of organic agriculture – potential negatives • Some practices less compatible with those that improve soil C sequestration – some increase GHG emissions • Unless productivity can be maintained, more land could be required for agriculture – sometimes called displacement / “leakage” – disastrous for soils and climate • Can we reduce animal numbers under organic farming? • Applying manure in organic systems – this would be applied elsewhere anyway (in non-organic systems) – so is this genuine C sequestration? • Can we maintain productivity increases without mineral N? To do so, do we need better cultivars with improved N use efficiency? If so, do we need GM?

5. The role of organic agriculture – potential negatives • Some practices less compatible with those that improve soil C sequestration – some increase GHG emissions • Unless productivity can be maintained, more land could be required for agriculture – sometimes called displacement / “leakage” – disastrous for soils and climate • Can we reduce animal numbers under organic farming? • Applying manure in organic systems – this would be applied elsewhere anyway (in non-organic systems) – so is this genuine C sequestration? • Can we maintain productivity increases without mineral N? To do so, do we need better cultivars with improved N use efficiency? If so, do we need GM?

6. Practices used in organic systems that can increase GHG emissions. e.g. • Manure may give higher N2O emissions than mineral fertiliser when applied and when in storage • Increased energy input from mechanical weeding compared to herbicides (even after accounting for the energy input in herbicide manufacture) • Increased tillage (for mechanical weeding) may reduce soil C relative to zero tillage (difficult in organic farming)

7. The role of organic agriculture – potential negatives • Some practices less compatible with those that improve soil C sequestration – some increase GHG emissions • Unless productivity can be maintained, more land could be required for agriculture – sometimes called displacement / “leakage” – disastrous for soils and climate • Can we reduce animal numbers under organic farming? • Applying manure in organic systems – this would be applied elsewhere anyway (in non-organic systems) – so is this genuine C sequestration? • Can we maintain productivity increases without mineral N? To do so, do we need better cultivars with improved N use efficiency? If so, do we need GM?

8. Agricultural GHG emissions

9. yield, t/ha land required, ha/tonne 0 N applied, kg/ha Land use change ? Deforestation Slide from Pete Berry (ADAS)

10. Effects of land use change Figures are calculated over a 30 year period Slide from Pete Berry (ADAS)

11. The role of organic agriculture – potential negatives • Some practices less compatible with those that improve soil C sequestration – some increase GHG emissions • Unless productivity can be maintained, more land could be required for agriculture – sometimes called displacement / “leakage” – disastrous for soils and climate • Can we reduce animal numbers under organic farming? • Applying manure in organic systems – this would be applied elsewhere anyway (in non-organic systems) – so is this genuine C sequestration? • Can we maintain productivity increases without mineral N? To do so, do we need better cultivars with improved N use efficiency? If so, do we need GM?

12. Livestock • Accounts for 9 percent of CO2 • Generates 65 percent of human-related nitrous oxide (mostly from manure). • Accounts for respectively 37 percent of all human-induced methane (and 64 percent of ammonia, which contributes significantly to acid rain). • Primary consumption of crops (by humans) is more efficient than feeding to livestock and then consuming the livestock / products FAO (2006)

13. Agricultural GHG emissions CH4 and N2O emissions by world region, 1990-2020 • Agriculture - 5.1 to 6.1 GtCO2-eq/yr in 2005 (10-12% of total global anthropogenic emissions of GHGs). • CH4 contributes 3.3 GtCO2-eq/yr and N2O 2.8 GtCO2-eq/yr. • Of global anthropogenic emissions in 2005, agriculture accounts for about 60% of N2O and about 50% of CH4. Smith et al. (2007)

14. The role of organic agriculture – potential negatives • Some practices less compatible with those that improve soil C sequestration – some increase GHG emissions • Unless productivity can be maintained, more land could be required for agriculture – sometimes called displacement / “leakage” – disastrous for soils and climate • Can we reduce animal numbers under organic farming? • Applying manure in organic systems – this would be applied elsewhere anyway (in non-organic systems) – so is this genuine C sequestration? • Can we maintain productivity increases without mineral N? To do so, do we need better cultivars with improved N use efficiency? If so, do we need GM?

15. Manure Manure Mineral N Are we actually sequestering carbon or just moving it about? More manure here….but……..less manure here Conventional farm Organic farm Effect over the whole cropland area = zero

16. The role of organic agriculture – potential negatives • Some practices less compatible with those that improve soil C sequestration – some increase GHG emissions • Unless productivity can be maintained, more land could be required for agriculture – sometimes called displacement / “leakage” – disastrous for soils and climate • Can we reduce animal numbers under organic farming? • Applying manure in organic systems – this would be applied elsewhere anyway (in non-organic systems) – so is this genuine C sequestration? • Can we maintain productivity increases without mineral N? To do so, do we need better cultivars with improved N use efficiency? If so, do we need GM?

17. Recorded and projected population (o) and grain production () (adapted from Dyson, 1996) Slide from Peter Gregory, SCRI

18. World cereal yield and area harvested per capita (extended from Dyson, 1996) Slide from Peter Gregory, SCRI

19. Can we replace mineral N altogether? Erisman et al. (2008)

20. Can we replace mineral N altogether? Erisman et al. (2008)

21. Personal perspectives • I grow my own fruit and veg. organically • I usually buy organic produce but… • …I also want to buy fair trade food • …I try to buy from my local farm shop – they are not organic farmers but are part of the small rural community where I live – I want to support them • I am vegetarian – much more efficient and less GHG per unit product. Consuming much less meat would be environmentally beneficial – reduces the organic manures available for organic farming • There are multiple drivers (economic, cultural, societal, scientific, ideological) that determine our choices in the developed world - farmers / consumers in developing countries have very little choice • I would hate to see us simply export our emissions • In my opinion, organic agriculture might be part of the solution, but is not the solution

22. Thank you for your attention