Presentation at our ESPP – IFOAM EU stakeholder meeting Closing nutrient cycles and uptake of recycled fertilisers (12/12/2018) See all outputs of the stakeholder meeting at our ESPP website: http://www.phosphorusplatform.eu/organic-agriculture

1. Improved Phosphorus
Recycling: Navigating
between Constraints
PD Dr. Kurt Möller
Universität Hohenheim

2. Outline
• Introduction
• Composition and assessment of the agronomical
value
• Environmental impact by LCA study
• Risk assessment (potentially toxic elements)
• Evaluation of the PTE loads
• Conclusions

3. Overview IMPROVE-P
Work packages:
- Compilation of existing knowledge and synthesis on P status of
organic farms
- Evaluation of efficacy and potential environmental impacts of
recycled P fertilizers
- Improved P mobilization by adapted agronomic strategies and
addition of P mobilizing Plant Growth Promoting Rhizobacteria
- Discussions with stakeholders about applicability of recycled P
fertilizers
3
IMproved Phosphorus Resource efficiency in Organic agriculture Via
recycling and Enhanced biological mobilization

4. Distribution of farm scale soil extractable P values among P
classes ranging from very low (P Class 1) to very high (P Class 5)
(n = 15,506) (Cooper et al. 2018)
10 % 28 % 38 % 18 % 6 %
1 2 3 4 5
2000
P class
1000
3000
4000
5000
6000
no.ofobservations

5. Distribution of field scale soil extractable P values among P
classes ranging from very low (P Class 1) to very high (P Class 5),
disaggregated by farm type. (n = 15,506) (Cooper et al. 2018)
2000
1000
3000
4000
no.ofobservations

6. Phosphorus potentials of recycled P sources in Germany
(based on data of Fricke & Bidlingmaier 2003)
Mg P a-1
0 20,000 40,000 60,000
other
paper industry
Green wastes and
household bio-wastes
slaughter wastes
Biosolids

7. Materials and Methods
• Pot and field experiments to assess the P fertilizer
value
• Compilation of the literature findings about the
relative P fertilizer effectiveness of recycled P
fertilizers
• LCA study (functional unit: 1 kg P)
• Risk assessment (accumulation risk for PTEs and
POPs)
• SWOT analysis

8. Composition of recycled P fertilizers [% DM]
(Möller et al. 2018)
0
10
20
30
40
50
60
70
80
90
OM N P K

9. -25
0
25
50
75
100
125
150
175
200
225
Relative fertilizer P effectiveness [% TSP] of some
major P sources (adapted from Möller et al. 2018)
RelativePeffectiveness[%ofTSP]

10. -25
0
25
50
75
100
125
150
175
200
225
RelativePeffectiveness[%ofTSP]

11. Soil pH and relative P efficiency of PR
(Möller et al. 2018)
y = 6.46x2 - 95.2x + 355
R² = 0.33
-100
-50
0
50
100
150
200
250
4.0 4.5 5.0 5,5 6.0 6.5 7.0 7.5 8.0 8.5 9.0
Soil pH
RelativePeffectiveness[%]

12. Influence of the soil pH on the relative P fertilizer
effectiveness of struvite [% of water soluble P fertilizer]
(Möller et al. 2018)
RelativePeffectiveness[%]
0
25
50
75
100
125
150
175
200
4 5 6 7 8 9
y = 85.7e0.0169x
R² = 0.00
Soil pH

13. Net LCA results per kg P for urban organic household
wastes (UOW), composted or digested (Hörtenhuber
et al. 2018)
-50
-25
0
25
50
75
UOW Compost
UOW-Compost
Low emissions
UOW-Digestate
ADP
[10-8 kg Sb-eq
kg-1 P]
FED
[101 MJ
kg-1 P]
GWP
[kg CO2-eq
kg-1 P]
AP
[10-2 kg SO2-
eq kg-1 P]
EP
[10-2 kg PO4-
eq kg-1 P]
-102-112-136

14. Net LCA results per kg P for sewage sludge (SS)-based recycled
P-fertilizers compared to PR and TSP (Hörtenhuber et al. 2018)
-50
-25
0
25
50
600
PR TSP SS SSA SSA-Ashdec SSA-Leachphos SS-Mephrec SS-Airprex SS-SSL
≈≈ 54.6
596 607
ADP
[10-8 kg Sb-eq
kg-1 P]
FED
[101 MJ
kg-1 P]
GWP
[kg CO2-eq
kg-1 P]
AP
[10-2 kg SO2-
eq kg-1 P]
EP
[10-2 kg PO4-
eq kg-1 P]

15. Concentration of PTEs [mg kg-1 DM] (Möller et al. 2018)
0
500
1000
1500
2000
2500
3000
3500
4000
Cd Pb Cr Ni Hg Cu Zn

16. Risk Assessment: soil Cd-accumulation [mg kg-1 soil] with yearly
application of recycled P fertilizers (equiv. 11 kg P/ha*a; soil pH: 7; water
balance: 100 mm m-2) (based on Weissengruber et al. (submitted))
0
0.25
0.5
0.75
1.0
1.25
Compost green waste OF
Compost biowaste OF
Composte catering waste
Cattle solid manure
Digestate OF
Digestate catering waste
Sewage sludge liquid
Sewage sludge solid
Meat and bone meal
Struvite Stuttgart
Struvite Airprex
SSAsh untreated
SSAsh Leachphos
Na-SSAsh Ashtec
SSAsh Mephrec
Phosphate rock
Triplesuperphosphate
no fertilizer
years
TSP
Composts, PR,
Soil base value
Soil threshold value

17. Risk Assessment: soil Zn-accumulation [mg kg-1 soil] with yearly application of
recycled P fertilizers (equiv. 11 kg P/ha*a; soil pH: 7; water balance: 100 mm m-
2) (based on Weissengruber et al. (submitted))
0
20
40
60
80
100
120
140
160
1 26 51 76 101 126 151 176 201
Compost green waste OF
Compost biowaste OF
Composte catering waste
Cattle solid manure
Digestate OF
Digestate catering waste
Sewage sludge liquid
Sewage sludge solid
Meat and bone meal
Struvite Stuttgart
Struvite Airprex
SSAsh untreated
SSAsh Leachphos
Na-SSAsh Ashtec
SSAsh Mephrec
Phosphate rock
Triplesuperphosphate
years
Biosolids,
digestates
Composts
Soil base value
Soil threshold value
Struvite, MBM,
TSP, PR

18. Average relative increase of the soil PTE concentration (%
between base and threshold values) by continuous application of
recycled P fertilizers (based on Weissengruber et al. (submitted))
-10
0
10
20
30
40
50

19. Heavy metal-nutrient index and Heavy metal- P index
of different recycling fertilizers (Möller et al. 2018)
0
2.5
5
7.5
HMN HMP

20. Correlation between the HMP-index and the mean
relative increase of soil PTE concentration (Möller et
al. 2018)
-5
0
5
10
15
20
25
30
35
40
45
0 1 2 3 4 5 6 7 8
MeanrelativeincreasePTEconc.[%]
Heavy Metal-Phosphorus-index
Composts
Biosolids, UOW
digestates, SS-Ashes,
Rhenania Ash Dec, TSP
converter slags,
LeachPhos, Struvite,
meat and bone
meal, catering waste
digestates
Risk assessment indicate no soil accumulation risk for the organic
pollutants PCB, PAH and PCDD/F

21. SWOT-Analysis
P
recovery
P fertilizer
value
Organic
matter
PTEs Organic
Pollutants
Env.
impact
Overall
Score
Bio-waste
compost
Bio-waste
digestates
Meat and
bone meal
- ashes
Sewage
sludge
- Struvite
(AirPrex)
- Struvite
(Stuttgart)
- AshDec
Rhenanite
4
3
2
1
?
?

22. Conclusions
• Plant P availability of many recycled P fertilizers is higher
than phosphate rock
• Main challenge are neutral soils:
• untreated ashes, PR and MBM are not recommended,
• composts, digestates, Na-Ash and struvite are more suitable.
• Many currently not permitted recycled P fertilizers have
lower potential harmful effects and environmental
impacts than permitted inputs
• PTEs are not the main constraint limiting recycling of
most RPFs
• PTE flows are mainly driven by the RPF nutrient
concentration  we do need a nutrient concentration
related definition of threshold values

23. Conclusions
• For organic pollutants, pharmaceuticals etc. in RPFs and
(conventional) manures uncertainties remain about risks
to human health and the environment
• Approaches to reduce the risks from organic pollutants in
RPFs are accompanied by several shortcomings:
• Reduced P recovery rates
• Increased abiotic resource depletion potential
• Increased GHG, energy inputs, etc.
• Lower P fertilizer value, loss of OM, N, S, etc.
• the current regulatory balance between the principle of
care and the principle of ecology favors our generation at
the expense of future generations.
• Presumably this balance is a result of considerations of
risk mainly to our generation.

24. Thank you very much!
https://improve-p.uni-
hohenheim.de
Financial support for this project is provided by funding bodies within
the FP7 ERA-Net CORE Organic II