Workshop on Ecologically Sound Use of Biowaste in the EU
Brussels, 31 May – 1 June 2006
Key benefits of compost use for
the soil-plant system
Rainer Kluge
State Agricultural Analytical and Research Institute
Augustenberg
Karlsruhe, Germany
Advantages of composts (Overview)
Saving potentials
Nutrients
Phosphorus
Potassium
Magnesium
Nitrogen
Fertilization
Value giving materials
Organic
Matter Humusrepro
Lime
Soil improvement
Sources
Value giving materials and nutrients in
composts
Current test results on quality parameters of
composts povided by Bundesgütegemeinschaft
Kompost e.V., Germany
Value giving materials: organic matter (OC)/ humus
annually balance input by compost/ requirement of soil
Input of compost 6 - 7 t/ha DM
Input of compost 10 t/ha DM
Medium humus requirement *
High humus requirement **
2,5
Means
Humus-C in t/ha
2,0
1,5
≈ to +
1,0
0,5
0,0
total
reproducible
Humus-C-input by compost
optimum
suboptimum
Humus requirement of soil
Crop rotation: * medium – Maize/ W.Wheat/ W.Barley
** high
– Sugarbeet/ W.Wheat/ W.Barley
Value giving materials: organic matter (OM)/ humus
annually balance input by compost/ requirement of soil
Input of compost 6 - 7 t/ha DM
Input of compost 10 t/ha DM
Medium humus requirement *
High humus requirement **
Humus-C in t/ha
2,0
1,5
Means
About 50 % of
OM input
≈ to +
1,0
0,5
0,0
reproducible
Humus-C-input
optimum
suboptimum
Humus requirement of soil
Crop rotation: * medium – Maize/ W.Wheat/ W.Barley
** high
– Sugarbeet/ W.Wheat/ W.Barley
Value giving materials: lime
annually balance input by compost/ requirement of soil
6,0
6 - 7 t/ha DM
lime requirement *
10 t/ha DM
Means
CaO in dt/ha
5,0
4,0
≈
3,0
2,0
1,0
0,0
Input
by Compost
* Preservation liming
light
heavy
Soils
Nutrients annually balance
input by compost/ removal by harvest
175
Input of compost 6-7 t/ha DM
Medium removal by harvest *
Input of compost 10 t/ha DM
High removal by harvest **
Means
Nutrients in kg/ha .
150
125
100
75
≈ to (-)
- to +
50
25
+
≈
0
N
P2O5
K2O
MgO
Crop rotation: * medium – G.Maize/W.Wheat/W.Barley ** high – S.Maize/W.Wheat/W.Barley
Removal:
without straw
Sources
Value giving materials and nutrients in
composts
Current test results on quality parameters of
composts povided by Bundesgütegemeinschaft
Kompost e.V., Germany
Effects on soil fertility and plant growth
Results from long-term field studies in
South-West-Germany, LUFA Augustenberg
Results on compost use in the humus reproduction
of soils, Reinhold und Partner, Germany
Experimental basis
of the project
12 years
Long-term field studies with
compost on five typical locations
Soils: predominantly
medium to heavy
Quality-assuranced composts
Uniform experimental design
Uniform crop rotation
Maize/W.Wheat/W.Barley
• Forchheim
Fra
n ce
• Weierbach
9 years
• Ellwangen
•
Heidenheim
SouthSouth-WestWest-Germany
• Stockach
Switzerland
Long-term studies with compost
in Baden-Württemberg
– Experimental basis of the project –
Location
Region
Soil type
Content of
clay %
Type of
compost
Duration (a)
Forchheim
Rheinebene
loamy sand
10
biowaste
12
Weierbach
Kraichgau
silty loam
27
garden mat.
12
Stockach
Hegau
silty clay loam
26
biowaste
12
Ellwangen
Ostalb
silty clay loam
29
biowaste
9
Heidenheim
Ostalb
silty loam
27
biowaste
9
Experimental design
Nr. of
variant
Factors of experiment
Compost application
min. N fertilization
annually in t/ha DM
annually in % of Optimum
1
without
without
2
without
50
3
without
100
4
5
without
5
5
50
6
5
7
10
Optimum100
range for
without
plant production
8
10
50
9
10
100
10
20
without
11
20
12
20
Extreme range
50
100
Organic matter (OM) Effects of compost on humus
content/ humus reproduction of soil
Average input with compost
rates of annually 6 – 7 t/ha DM:
Result of the project:
Humus content of the soil
after 8 resp. 11 years
OM input = 2,5 – 3,0 t/ha DM
Stabilization resp. slight increase of
humus contents
High performance of humus
reproduction
more than 50 % of the total C in
compost consists of stable
humus C forms
Sustainable humus reproduction
is ensured by these stable forms of
humus
Compost rate in t/ha DM .
Practical consequences:
20
10
0,2 – 0,6 %
5
Humus content without
compost = 2,5 %
0,0
0,5
1,0
Increase of humus content in %
1,5
Lime (CaO) Effects of compost on
the pH value/ state of lime of the soil
Result of the project:
Average input with compost
rates of annually 6 – 7 t/ha DM:
pH value of the soil
after 8 resp. 11 years
Practical consequences:
Stabilization resp. slight
increase of the pH values
Lime input corresponds to
preservation liming
Compost rate in t/ha DM .
Input of lime = 2,0 – 4,0 dt CaO/ha
20
10
0,2 – 0,4 pH
pH value without
compost = 6,4
5
0,0
0,2
0,4
Increase of pH value
0,6
0,8
Supply of nutrients Effects of compost on the
soluble nutrient contents (P, K, Mg) of the soil
Average input with compost
rates of annually 6 – 7 t/ha DM:
Result of the project:
Nutrient supply in kg/ha
P2O5 = 40 – 50
K2O = 60 – 80
MgO = 45 – 60
High fertilizer effect of P und K
- Contents remain at starting
level resp. increase slightly
- High fertilization efficiency,
input ≈ basic supply
- Full accounting in the
fertilization balance both
nutrients are limiting factors
of compost application
Smaller fertilizer effect of Mg
Compostgift
giftinint/ha
t/haDM
DM . .
Compost
Practical consequences:
Nutrient contents of the soil
after 8 resp. 11 years
20
20
starting
level
starting
level
10
10
5
5
P2O5
K2O
0
0
0
0
20 30
10 10
20
Contents
Contents of
of soluble
soluble nutrients
nutrients in
in mg/100
mg/100 gg
30
40
High input of total Nitrogen by compost
correct charging in the fertilizer balance
Result of the project:
N utilization and N fertilization effect is very small,
increases only gradually
Compost
a) N utilization
20 %
Plant nutrition
Charging in the N fertilizer balance (annually):
Short-term
(1 – 3 years) = 3 – 5 %
80 %
Humus
Medium-term (5 – 10 years)
= 8 – 10 %
reproduction
b) Effects on nitrate content of soil
Result of the project:
Increase with regular
application of compost:
only about
5 – 10 kg/ha
Conclusions:
• N mineralization takes place relatively slowly and
thus can be controlled
• Strong organic N sorption prevents unexpected N
mobilization events and leaching into the
groundwater
Precautions measures:
Regular control of nitrate contents of soils
Reduction of additional N fertilization by 10 – 15 %
Physical and biological soil characteristics
Soil improvement by use of compost (1)
Improved parameters
Effects on soil use
Physics and water regime of soils
Increased stability of soil
crumbs
Faster warming up of
soils
growth promotion in spring
Soil porosity
Bulk density
improved aeration and drainage of soils
Increased water capacity
and moisture infiltration
buffers negative effects of weather extremes
increased water storage reduces drying stress
better permeability help to avoid stagnant
water
more stable soil structure
enhanced pressure resistance
improved workability saving fuel consumption
less erosion reduction of soil losses
Physical and biological soil characteristics
Soil improvement by use of compost (2)
Improved parameters
Effects on soil use
Soil biology
Increased microbial
biomass
increased biological activity
activation of soil life
better tilth of soil
higher phytosanitary loadability decrease of
pathogens in the soils
Increased enzyme
activities
closer C/N ratio in soils
improved mineralization of the organic material increased N mineralization
gradual enhancement of the soil fertility
improved soil use
soil conservation
Benefits of composts for plant cultivation
conclusions (1)
Composts = organic NPK fertilizers
benefits
= sum of all particular effects
Main medium-term benefit Humus reproduction of soils
Advantages of compost
high portions of carbon, just right for reproduction build-up of humus
soil improvement in general better use of soil, stabilization of crop yield
increasing importance for maintenance/ enhancement of soil fertility
Because: organic matter for the soil will become less available (!)
negative humus balance
- in commercial farms humus is often lacking
- increasing sales of straw (to industries, for renewable energy production)
- other resources are less suitable (i.e. liquid manure)
Benefits of composts for plant cultivation
conclusions (2)
Additional benefits
Fertilization and liming = Saving potentials
Input lime
stabilization of pH value
subtitutes preservation liming
Input nutrients (P, K, Mg)
high fertilization efficiency
subtitutes basic supply
Nitrogen
only low fertilization efficiency
It is a matter of economical and ecologic reason to use composts preferably in
agriculture, because they optimal fulfil the requirements for a sustainable
cycling „Best Option“
reliable hygienic material
sustainable humus reproduction
broad nutrient effects
minor and calculable risks
to avoid problems with bad hygiene
enhancement of the soil fertility
saving of fertilizers (basic supply)
environmentally safe use of composts