Nitrogen balance on farms and meaning of field effect

1
Twinning Light Project No LV/2004/AG 02TL
Implementation of Action Program for vulnerable
zones subject to special requirements for
protection of waters and soil against pollution
caused by nitrates from agricultural sources in
accordance with the requirements of EU Directive
91/676/EEC

• Nitrogen balance on farms and meaning of field
  effect
• By
• Torkild Birkmose
• Adviser

Seminar on the EU MS experience in elaboration of
the legal basis for use of Best Environmental
practice and Best Available Technology, Ozolnikei
15 16 June 2006
2
The more manure the higher N-surplus on the
farm
250
200
150
N-surplus, kg N per ha
100
50
0
50
100
150
200
250
Animal manure, kg N pr. ha
3
Nitrogen -organic or inorganic?
4
Organic or inorganic?

• Inorganic nitrogen
• Ammonium (NH4), which the plants can uptake
  immediately by the roots
• Organic nitrogen
• Residues of fx amino acids, proteins feed,
  bedding, micro organisms etc. Not plant available
  before digested by micro organisms in the soil

5
Mineral fertilizer No content of organic nitrogen
6
Liquid manure Low content of organic nitrogen
7
Solid manure High content of organic nitrogen
8
Content of inorganic N in animal manure
9
Field effect a definition

• The amount of nitrogen in mineral fertilizer
  that can give the same yield as 100 kg of total-N
  in animal manure the first year after
  application.

10
How is field effect calculated?
63
11
Content of ammonia cannot predict the field
effect alone!
100
Y 1,04x - 9,52 R2 0,63
80
60
Field effect, percent
40
20
0
0
20
40
60
80
100
Content of ammonium, percent
12
Factors to affect the field effect

• Manure type (content of ammonium)
• Crop
• Ammonia evaporation
• Temperature
• Wind speed
• Crop cover
• Rain fall
• Incorporation in soil
• Time of the year
• Application technique

13
Field effect of nitrogen in animal manure applied
in spring to spring barley,
Deep litter
Solid manure
Cattle slurry
Pig slurry
0
20
40
60
80
Field effect, percent
14
Best field effect of spring applied manure
Solid manure applied in spring
Solid manure applied in autumn
0
20
40
60
Field effect, percent
15
Better field effect in spring sown crops than in
winter sown crops
Deep litter
Cattle slurry
Pig slurry
Field effect, percent
0
20
40
60
80
Winter wheat
Spring barley
16
Application in winter wheat with trailing hoses
17
Injection in bare soil
18
Injection of slurry improves the field effect
Trailing hoses
Injection
Field effect, percent
0
20
40
60
80
Spring barley, cattle slurry
Winter wheat, pig slurry
19
Field effect, Danish recommendations, example
solid manure
20
Minimum field effect demanded by the Danish
legislation, first year second year