The document discusses several topics related to farming in the UK: 1) wheat yields have increased due to new technologies like herbicides and fungicides but still lag behind the US, 2) nitrogen inputs have environmental impacts through emissions like nitrous oxide and nitrate leaching into water supplies, and 3) current farming systems rely heavily on nitrogen for yields but need to reduce nitrogen losses to improve sustainability.

1. Farming Futures – March 2010
Are we farming in the right way?
Jim Orson
© Copyright text

2. Farming Futures – March 2010
UK competitiveness based on technology
Average wheat yields (t/ha)
t/ha Effective
9
Effective fungicides
8
7 herbicides
6
5
4
Increase in N
3
2
1
Semi-dwarf
varieties
0
68
73
78
83
88
93
98
03
08
19
19
19
19
19
19
19
20
20
© Copyright text USA UK

3. Farming Futures – March 2010
Agriculture & Nitrogen:
what goes in must come out
Air
NH3 N2O NOx N2
N INPUTS N OUTPUTS
e.g. manure, e.g. crops,
fertiliser, etc. milk, meat, etc
NO3- NH4+ NO2- DON
© Copyright text Soil and Water

4. Farming Futures – March 2010
Crop yields and nitrate leached from Broadbalk
(1st wheat; Hereward)
N leached (kg/ha) Yield (t/ha)
90 10
80 9
70 8
60 7
Economic 6
50 optimum 5
40
4
30 3
20 2
10 1
0 0
0 48 96 144 192 240 288 - 250 346
as fertiliser as manure
© Copyright text N applied (kg/ha/yr)

5. Farming Futures – March 2010
Organic – less energy, more nutrient polluting
and land hungry and similar global warming
potential per tonne
Conv. Org. Conv.
Org. feed
bread bread feed
wheat
wheat wheat wheat
Impacts & resources used
Primary energy used, GJ 2.46 1.74 2.24 1.72
Global warming pot'l 0.70 0.78 0.63 0.68
Eutrophication pot'l 3.11 9.26 2.97 8.31
N losses, kg/t
NO3—N 4.4 18.3 4.3 16.4
From Defra Project report IS0205 by Williams and Audsley, Cranfield University
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6. Farming Futures – March 2010
UK greenhouse gas emissions
Agriculture contributes:
• 7% of the UK’s greenhouse gas emissions
• 67% of nitrous oxide emissions
• 39% of methane emissions
• 1% of carbon dioxide emissions
• Nitrous oxide (N2O) is 296 times as powerful a GHG
than CO2
• Methane(CH4) is 23 times as powerful a GHG than
CO2
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7. Farming Futures – March 2010
N fertiliser – 50% of the energy for wheat
production but 80% of GHG emissions
Energy inputs GHG emissions
GJ/ha (% of total chain) Kg C02eq/ha (% of total chain)
Diesel 4.7 (29%) 356.6 (11%)
N fertiliser 7.5 (46%) 2,528.6 (81%)
P fertiliser 0.7 (4%) 29.1 (1%)
K fertiliser 0.4 (2%) 21.0 (1%)
Pesticides 0.6 (4%) 10.8 (0.5%)
Seeds 2.5 (15%) 160.4 (5%)
Total 16.4 3,106
Source: Rickeard et al., 2004
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8. Farming Futures – March 2010
Energy and GHG – form of N
Energy GHG
MJ/kgN @ CO2eq/kgN
Plant gate Production
and use
Urea 44.1-51.6 10.5-10.9
AN 30.2-40.6 8.4-11.8
CAN 31.4-42.6 7.6-11.1
UAN 38.2-47.6 10.6-12.5
© Copyright text
Brentrup & Palliere, 2008

9. Farming Futures – March 2010
Is it possible to increase the sustainability of arable and ruminant agriculture by reducing inputs?
M.J. Glendining, A.G. Dailey, A.G. Williams, F.K. van Evert, K.W.T. Goulding, A.P. Whitmore.
Agricultural Systems 99 (2009) 117–125
Breakdown of the environmental costs/tonne wheat (a), OSR (b)
according to N dose (kg/ha). Loss of ecosystem services resulting
from Copyright text
© conversion of forest to agricultural use is fully costed

10. Farming Futures – March 2010
GHG emissions/tonne of winter oilseed rape production
(treated with fungicides to control diseases or untreated)
Mahmuti et al. Int. J. Ag Sustainability 7(3) 2009
1200
Treated
Untreated
-1
1000
kg CO 2 eq. t
800
600
2005 2006 2007 2005 2006 2007
Rothamsted ADAS
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ADAS sites were Teversham (2005) and Boxworth (2006-2007)

11. Farming Futures – March 2010
Current farming systems
• Nitrogen is a key issue in terms of yield,
energy use and environmental impact
• Whilst there is growing evidence that around
current doses can be justified on
environmental grounds there is a need to
reduce, if possible, nitrate leaching and
nitrous oxide production
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