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MANUSCRIPT Journal of Applied Phycology
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Title:
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The use of microalgae as a high-value organic slow-release fertilizer results in tomatoes with increased
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carotenoid and sugar levels
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Supplementary information
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Joeri Coppens1*, Oliver Grunert1*, Sofie Van Den Hende2, Ilse Vanhoutte3, Nico Boon1, Geert
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Haesaert4, Leen De Gelder3 
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Laboratory of Microbial Ecology and Technology (LabMET), Department of Biochemical and Microbial
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Technology, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Gent,
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Belgium
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2
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Sciences, Faculty of Bioscience Engineering, Ghent University, Graaf Karel de Goedelaan 5, 8500
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Kortrijk, Belgium
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3
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Engineering, Ghent University, Valentin Vaerwyckweg 1, 9000 Gent, Belgium
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4
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Ghent University, Valentin Vaerwyckweg 1, 9000 Gent, Belgium
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
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Tel.: + 32 9 243 24 75
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E-mail: leen.degelder@ugent.be
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*
Laboratory of Industrial Water and Ecotechnology (LIWET), Department of Industrial Biological
Laboratory for Environmental Technology, Department of Applied Biosciences, Faculty of Bioscience
Laboratory for crop production, Department of Applied Biosciences, Faculty of Bioscience Engineering,
Corresponding author:
Equally contributed
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1. Tomato cultivation experiment
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1.1.
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Table S 1. Chemical and physical characteristics of the organic growing medium
Constituents of the organic growing medium
Parameter
pH
4.40 ± 0.10
Parameter
Value
Ash
3.5 ± 0.6
90.63 ± 20.99
Dry weight (%)
41.5 ± 0.6
Organic N (mg L-1)
0.32 ± 0.55
Shrinking (%)
21.0 ± 1.8
NO2--N (mg L-1)
0.00 ± 0.00
Air volume (%)
33.0 ± 4.4
NO3--N (mg L-1)
6.78 ± 5.14
Organic matter (% of DM)
96.5 ± 0.6
NH4+-N (mg L-1)
6.05 ± 0.51
Bulk density (g L-1)
P (mg L-1)
8.51 ± 1.31
Total pore volume (%)
92 ± 0.8
K+ (mg L-1)
103.75 ± 31.43
Moisture content (%)
58.5 ± 0.6
Ca2+ (mg L-1)
174.5 ± 28.72
Water capacity (g 100 g-1
DM)
448.5 ± 52.3
Mg2+ (mg L-1)
54.75 ± 5.46
Water volume pF1 (%)
59.25 ± 4.0
SO42- (mg L-1)
13.85 ± 3.01
Water volume pF2 (%)
40.5 ± 3.4
Na+ (mg L-1)
42.75 ± 9.16
Water availability (PF1-PF2)
(%)
Cl- (mg L-1)
76.80 ± 24.43
Conductivity (µS cm1
)
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Value
Fe2+/3+ (mg L-1)
0.10 ± 0.03
Mn2+ (mg L-1)
0.60 ± 0.11
143.5 ± 11.3
18.75 ± 3.86
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1.2.
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Table S 2. Mean values and standard error of means over the different treatments are displayed
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for the plant length and stem diameter. Bonferroni -Significant-Difference (p =0.05) are
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calculated for the tomato plants (n =3) per treatment and per time point.
Mean plant length and stem diameter
Inorganic
fertilizer
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Organic
fertilizer
MaB-flocs
Nannochloropsis
Plant length (cm)
162.5 ±3.8 a
145.6 ±3.8 b
143.2 ±3.8 b
139.2 ±3.8 b
Stem diameter (mm)
10.9 ±0.2
10.9 ±0.2
10.4 ±0.2
10.7 ±0.2
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2. Economic evaluation of algae-based fertilizers
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Different fertilizer scenarios are evaluated for their economic feasibility. For these scenarios the
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tomato fruit yield and fertilizer price differ, whereas other fixed and variable costs are assumed to
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be the same (Table S3). General fixed and variable costs of greenhouse tomato cultivation are
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obtained from a government survey greenhouse tomato farmers in Flanders, Belgium (Jourquin et
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al. 2013). Additional production data was obtained from DLV Plant (personal communication).
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Table S 3. Overview the of variable and fixed costs of greenhouse tomato cultivation, excluding fertilizer
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costs
Value (€ m-2)
Assumptions
References
CO2
2.6
46 kg CO2 m-2
DLV Plant (personal
communication)
heat
4.0
1548 MJ m-2
DLV Plant (personal
communication)
Electricity
0.6
80 W m-2
DLV Plant (personal
communication)
tomato plants
3.2
3.3 plants m-2
(Jourquin et al. 2013)
crop protection
0.5
Variable costs
(Jourquin et al. 2013)
The same price for
inorganic and organic
growing medium is
assumed
(Jourquin et al. 2013)
Peltracom (personal
communication)
growing medium
0.8
support and binding materials
0.5
(Jourquin et al. 2013)
other variable costs (incl. waste
management)
1.0
(Jourquin et al. 2013)
marketing
0.9
2% of turnover
DLV Plant (personal
communication)
transportation costs
0.2
0.4% of turnover
DLV Plant (personal
communication)
14.45
875 hr/1000 m² at
€16.5/hr
DLV Plant (personal
communication)
labour
Equipment & maintenance costs
0.5
(Jourquin et al. 2013)
Costs of buildings
4.0
(Jourquin et al. 2013)
Other fixed costs (insurances,
taxes,..)
0.9
(Jourquin et al. 2013)
depreciations
3.2
(Jourquin et al. 2013)
Total costs
37.2
Fixed costs
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excluding fertilizers
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A plant nutrient requirement of 133g N m-2, 34 g P2O5 m-2 and 233 g K2O m-2 is assumed
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according to commercial greenhouse tomato production practices (Haifa 2012). For inorganic
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fertilizer scenarios the commercial NPK fertilizer is amended with K2SO4 to provide the
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additional potassium demand, while the organic fertilizer scenarios are amended with kali
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vinasse. A tomato production yield of 52 kg m-2 yr-1 is assumed for the inorganic fertilizer
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treatments, according to average production yields in Flanders (Jourquin et al. 2013). A yield of
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35 kg m-2 yr-1 is assumed for the different organic fertilizer treatments (Dewitte et al. 2013).
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The cost for microalgae production is obtained from Coppens et al. (Under review) and is based
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on the economic evaluation of microalgae cultivation in an outdoor raceway pond according to
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Norsker et al. (2011). A microalgal production cost of € 23 kg-1biomass or € 288 kg-1N is
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obtained. Considering a 33% N mineralization of the microalgal biomass, a fertilizer cost of €
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871 kg-1 fertilizer-N is obtained.
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Table S 4. Price overview of different inorganic and organic fertilizers
Price (€/kg)
Reference
Inorganic NPK fertilizer
(14% N, 7% P, 15% K)
1.1
Peltracom (personal
communication)
K2SO4 (43% K)
0.65
Peltracom (personal
communication)
Organic slow-release
fertilizer SF1 (4% N,
2.2% P, 5% K)
0.42
Peltracom (personal
communication)
Organic slow-release
fertilizer SF2 (8% N,
2.2% P, 5% K)
0.58
Peltracom (personal
communication)
Kali vinasse (32% K)
0.88
Peltracom (personal
communication)
Fertilizer
Microalgae
(8% N, 1.3% P, 0.2% K)
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Table S 5. Overview of the production costs of the different fertilizer scenarios
Inorg. fert.
Inorg. fert. +
Inorg. fert. +
Org. fert.
10% algae
20% algae
Yield
Org. fert. +
10% algae
Org. fert. +
20% algae
100% algae
fert.
52.4
52.4
52.4
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35
35
35
37.2
37.2
37.2
37.2
37.2
37.2
37.2
Fertilizers
0.95 kg inorg.
0.50 kg algae
1.01 kg algae
2.46 kg SF1
0.50 kg algae
1.01 kg algae
5.03 kg algae
(m-2)
0.12 kg K2SO4
0.85 kg inorg.
0.76 kg inorg..
0.69 kg SF2
3.32 kg SF1
2.95 kg SF1
0.13 kg K2SO4
0.15 kg K2SO4
0.18 kg Kvinasse
0.13 kg K
vinasse
0.18 kg Kvinasse
0.54 kg Kvinasse
1.12
12.60
24.06
1.13
13.10
24.5
116.1
8.62
96.92
185.08
8.52
100.6
188.7
893.3
38.33
49.80
61.26
38.3
50.3
61.7
153.3
0.73
0.95
1.17
1.10
1.44
1.76
4.38
(kg m-2)
Costs excl.
fertilizer (€ m-2)
Fertilizer cost
(€ m-2)
Fertilizer cost
(€ kg-1
fertilizer-N)
Total cost
(€ m-2)
Total cost
(€ kg-1)
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References
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Coppens J, Meers E, Boon N, Buysse J, Vlaeminck SE (Under review) Follow the N and P road: highresolution nutrient flow analysis as precursor for sustainable resource management Sci
Total Environ
Dewitte J, Van Steenkiste J, Buyens S (2013) Rassenproef losse tomaten biologische teelt 2013
(Variety test of tomatoes through organic cultivation in 2013). Provincial test centre for
vegetable cultivation of East Flanders (PCG), Kruishoutem
Haifa (2012) Nutritional recommendations for tomato in open-field, tunnels and greenhouse. Haifa
Chemicals Ltd., Haifa, Israel
Jourquin S, Maertens E, Deuninck J, D’hooghe J (2013) Het bedrijfsinkomen van de tomatenteler:
resultaten van bedrijven uit het landbouwmonitoringsnetwerk (The income of the tomato
famer: survey results from the agricultural monitoring network). Beleidsdomein Landbouw
en Visserij, Brussels
Norsker N-H, Barbosa MJ, Vermuë MH, Wijffels RH (2011) Microalgal production — A close look at
the
economics
Biotechnol
Adv
29:24-27
doi:http://dx.doi.org/10.1016/j.biotechadv.2010.08.005
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