The Use of Composts in Agriculture
Mary Dimambro & Rob Lillywhite
Warwick HRI

Project outline
Rob Lillywhite
Warwick HRI

Staff at Warwick HRI
• Mary Dimambro
• Robert Lillywhite
• Clive Rahn
• Mary Turner

Programme
• Project outline
• Chemical characterisation of composts
• Field trial results
• Summary

EU landfill Directive (1999/31/EC)
BMW sent to landfill in the UK must be reduced to:
•75% of the amount produced in 1995 by 2010
•50% of the amount produced in 1995 by 2013
•35% of the amount produced in 1995 by 2020
Since 50%+ of municipal solid waste is biodegradable, that means finding alternative routes of disposal for:
• between 4.9 & 7.7 Mt by 2010
• between 10.6 & 15.5 Mt by 2020

Waste in the UK
• Municipal solid waste = MSW
• Biodegradable municipal waste = BMW
– Green waste
– Food waste
– Paper & cardboard

Composting in the UK
• 2003/04: 2 Mt BMW composted
– 84% green waste
– Composting of kitchen and other municipal wastes is in its infancy
• Area of up to 500,000 ha would be required to spread 15 Mt compost (rate: 250 kg N / ha)

Discussion of compost characteristics
Mary Dimambro

Talk summary
• The composts
• Compost analysis
• Results
• Summary

Sourcing the composts
• UK composters contacted
• At least 15 companies compost BMW
– Source segregated
– Mixed MSW
• 12 composts obtained

The composts
• 12 used for initial characterisation
• 5 selected for the field trial
A
H
F
I
G
J

Feedstock
Green waste
Straw
Fruit waste
Vegetable waste
Potato waste
Milk waste
Paper
Cardboard
Kitchen waste
Catering waste
Pet food waste
Manure
Mixed MSW
System
VE=In Vessel, OW=Open Windrow
9
9
9
A
9
The composts
G B
9
9
9
C
9
D
9
9
E
9
9
9
9
F
9
9
9
H
9
9
9
9 9
I
9
J
9
K
9
L
9
9
9
9
9
9
9
9
9
VE OW VE VE VE
9
VE VE VE OW VE OW OW

Compost analysis
• British Standard methods for soil improvers and growing media
• Recommended by BSI PAS 100
• Performed at
– Warwick HRI
– Direct Laboratories, Wolverhampton

Compost analysis
• Characterisation:
– Moisture content, bulk density, pH, conductivity, organic matter, nutrients
• Proximate analysis:
– Water soluble carbohydrates, cellulose, lignin, ash
• Heavy metals
• Total coliforms, E. coli , Salmonella
• Bioassay

Results: pH
10
9
8
7
6
5
4
3
2
1
0
A B C D E F G H I J K L
Compost

Results: Carbon
40
30
20
10
0
A B C D E F G H I J K L
Compost

Results: Nitrogen
2.5
2.0
1.5
1.0
Meat waste
0.5
0.0
A B C D E F G H I J K L
Compost

35
Results: C:N ratio
30
25
20
15
10
5
0
A B C D E F G H I J K L
Compost
20:1

5000
4000
Results: Nutrients
NO
3
NH
4
Mg
P
Fe
3000
2000
1000
0
A B C D E F G H I J K L
Compost

Results: Contaminants
25
20
15
Glass
Plastic
Metal
Stones
Other
72% MSW
10
MSW
5
0
A B C D E F G H I J K L
Compost

3 0 0
2 0 0
1 0 0
0
7 0 0
Results: Heavy Metals
6 0 0
5 0 0
P b
N i
Z n
C u
C r
Mixed MSW
4 0 0
A B C D E F G H
C o m p o s t
I J K L
Zn
Pb &
Cu

Methods: Germination Test

Composts used
Feedstock
A Green & kitchen waste, paper, cardboard
B Green waste, fruit & vegetable waste
F Green waste, fruit & vegetable waste, cardboard
G
J
MSW
Green & kitchen waste, paper, cardboard, catering waste

Methods: Germination Test
Compost
0%
25%
50%
75%
100%
Peat
100%
75%
50%
25%
0%
Day 14

Results: Germination
100
Compost G
80
60
40
20
0
0 5 10 15 20 25 30
0% compost
25% compost
50% compost
75% compost
Day
100% compost
0% compost
25% compost
50% compost
75% compost
100% compost
100
Compost J
80
60
40
20
0
0 5
0% compost
25% compost
50% compost
75% compost
100% compost
10 15 20 25 30
Day

Results: tomato yield
300
200
100
0
A B F G J Peat
Compost
0%
25%
50%
75%
100%

Bioassay summary
• 25% compost:
– does not inhibit germination
– does not reduce plant growth
• 100% compost:
– reduces germination
– reduces growth

Compost summary
• 100% MSW compost
– High physical contaminants (glass, plastic)
– High C:N ratio
– High heavy metals (some exceed PAS 100)

Compost summary
• Source segregated composts
– Generally within or close to PAS 100 limits
– Low physical contaminants (mostly stones)
– Low heavy metals
– Range of nutrient concentrations

Compost analysis
• More details in the technical report

The field trial
Rob Lillywhite

Breakdown of presentation
• Composts used
• Field trial design
• Data collection
• Results
• Discussion

F
J
A
B
G
Composts used
Feedstock
Green & kitchen waste, paper, cardboard
System
In-vessel
50% green waste,
50% fruit & vegetable waste
30-40% green waste, 60-70% fruit & vegetable waste, cardboard
VCU
Windrow
MSW In-vessel
Green & kitchen waste, paper, cardboard, catering waste
In-vessel
End use
Agricultural land, reclamation, landfill cover
Soil conditioner
Landscaping, agricultural land
Landfill cover
Soil conditioner

Field trial design
5 composts (A, B, F, G & J) x
3 treatments (250, 500 & 250+125 kg/ha N) +
6 fertiliser (0, 42, 84, 125, 167 & 250 kg/ha N) x
3 replicates = 63 plots

Field trial design
P1 P2 P3 P4 P5 P6 P7 P22 P23 P24 P25 P26 P27 P28 P43 P44 P45 P46 P47 P48 P49
P8 P9 P10 P11 P12 P13 P14 P29 P30 P31 P32 P33 P34 P35 P50 P51 P52 P53 P54 P55 P56
P15 P16 P17 P18 P19 P20 P21 P36 P37 P38 P39 P40 P41 P42 P57 P58 P59 P60 P61 P62 P63
B1 B2 B3

Compost incorporation
Compost
A
B
F
G
J
%N
1.73
1.61
1.01
1.08
2.16
Amount (t/ha) to give 250 kg/ha N
26.3
40.9
31.0
33.8
24.9
Amount (t/ha) to give 500 kg/ha N
53.7
81.8
62.3
67.6
49.8

Data collection
Barley
• Above ground yield – day 50
• Grain yield - final harvest
Soil
• Pre-drilling
• Pre-top dressing
• Post-harvest

Field trial
Location: Warwick HRI, Wellesbourne
Crop: Spring barley, variety Optic
Composts incorporated: 14 th March 2005
Drilled: 15 th March 2005
Harvested: 4 th August 2005

Yield pre top dressing
A
Zero N
5
4
3
2
1
0
7
6
B
A B
F
F G
G J
J
J
250
500

6
5
4
3
8
7
2
1
0
0
Grain yield at harvest
50 100 150
Applied nitrogen
200 250

N uptake at harvest
150
125
100
75
50
25
0
0 50 100 150
Applied nitrogen
Grain Total
200 250

Grain yield at harvest
8
7
125 N
6
Zero N
5
4
3
2
1
0
A B F G
250 500 250+125 N
MSW
J

Grain %N at harvest
2.5
125 N
2
1.5
Zero N 1
0.5
0
A B F G
250 500 250+125 N
J

140
120
125 N
100
Zero N
80
60
40
20
0
Grain N uptake at harvest
A B F G
250 500 250+125 N
J

160
140
125 N
120
100
Zero N
80
60
40
20
0
Total N uptake at harvest
A B F G
250 500 250+125 N
J

Soil min N (0-60 cm) at harvest
100
80
125 N
Zero N
60
40
20
0
A B F G
250 500 250+125 N
J

Heavy metal content of grain
The barley grain was analysed for:
• chromium
• copper
• lead
• nickel
• zinc
Application of compost G resulted in a slight increase in copper content and a significant increase in levels of zinc.

Heavy metal content of soil
Soils were analysed on 3 occasions for:
• chromium
• copper
• lead
• nickel
• zinc
Application of compost G resulted in a slight but not significant increase in levels of lead, nickel and zinc.

What does it all mean?
Composts A, F and J are suitable for application to agricultural land without adverse effects.
Compost F is the only compost with nitrogen fertilising value in the first year of incorporation.
Due to higher levels of heavy metals and sodium, compost G cannot be recommended for application to agricultural land.

Summary
Mary Dimambro

Compost summary
• All composts contain
• Organic matter
• Nitrogen
• Essential nutrients

Compost summary
• Source segregated composts
– Low physical contaminants
– Low heavy metals
– Range of nutrient concentrations

Compost summary
• 100% MSW compost
– High physical contaminants (glass, plastic)
– High heavy metals
– Range of nutrients

Field trial summary
• No significant fertilising effect was obvious in the first year of compost incorporation
• Composts A, F, and J
– containing mainly plant and food waste
– no adverse effects
– showed agricultural benefit

Field trial summary
• Compost B
– slightly reduced establishment and yield
– higher levels of lead and zinc
• Compost G
– adversely affected plant establishment and yield
– higher levels of all heavy metals

Recommendations
• Source segregated composts
– Low heavy metals
– Can be of agricultural benefit
• Compost + fertiliser best combination
• Mixed waste composts not recommended

Technical report
• Available soon as a pdf
• Please ensure we have your email address

Acknowledgements
• Onyx Environmental Trust
• DEFRA
• The compost suppliers
• Direct Laboratories
• Warwick HRI Analytical Laboratory