Nitrogen Cycling: Risks and Opportunities - Keith Goulding (Rothamsted Research)
risks and opportunities
Head: Department for Sustainable
Soils and Grassland Systems
Driving forces for better N utilisation
Projected population increase requires 50% more
food by 2030; 70% more by 2050.
Royal Society says we need ‘Sustainable
Intensification’. Cultivating more land risks
destruction of forests and large carbon losses.
N is the key to yield in most countries, but making N
fertiliser uses fossil fuels and produces greenhouse
Must improve NUE to reduce costs, fossil fuel use
and losses to air and water.
NB some room for greater use of legumes but not
Example: problem of poor NUE of meat
production. Intensive pig production from field to
‘Reactive nitrogen in the environment.’ UNEP 2007
Example: N surpluses on some UK farms
N surplus (= N inputs – N in product; kg N/ha)
Fertiliser N input (kg N/ha)
Organic Matter Mineral N
Approximate N content (kg ha-1
) : 2000-20000 10-500
Importance of N in soil organic matter
But still no quick and easy way of predicting
N release from soils
21/10/03 10/11/03 30/11/03 20/12/03 09/01/04 29/01/04 18/02/04 09/03/04 29/03/04 18/04/04
Low N Plot
High N Plot
N release very variable through the season:
nitrate in soil on Broadbalk field, Rothamsted
Tony Miller, Rothamsted
RB209: The Basis of Good Practice
Reliable information: soil type; regular soil
analysis; cropping fertiliser and manure history;
nutrient balances; winter rainfall.
Realistic estimate of crop yields and fertiliser
needs; take account of fertiliser prices.
Estimate SNS: RB209; PLANET, ‘Tried and
Utilise available nutrients in organic manures.
Careful selection of fertilisers – price and
Correct rate, method and timing of fertiliser
and manure applications; accuracy.
Good record keeping.
Probably not like this!
Better manure management
Better manure management
Estimate or measure N content
(RB209; MANNER); make allowance
when calculating fertiliser
Recycle effectively – band
Where possible, apply from late
Measure application rate
Manure Management Plan
‘Tried & Tested’ SNS
You can use our SNS calculator
to help you determine the Soil
Nitrogen Supply of your soil. You
will need this index number when
using the ‘Fertiliser Manual
(RB209)’ for guidance on
fertiliser application rates.
Tried & Tested SNS Calculator
Improving NUE involves assessing risk and
eliminating ‘leaky’ practices
Could also consider:
Precision seeding and fertiliser
Rothamsted Research is an
institute of the UK Biotechnology
and Biological Sciences
The UK Department for
Environment, Food and Rural
Affairs funded some of the
research described in this talk.