Bioponics—An Organic Closed-Loop Soilless Cultivation System: Yields and Characteristics Compared to Hydroponics and Soil Cultivation
Metadata
- Cite key: gartmannBioponicsOrganicClosedLoop2023
- Item type: Journal Article
- Authors: F. Gartmann, J. Hügly, N. Krähenbühl, N. Brinkmann, Z. Schmautz, T.H.M. Smits, R. Junge
- Affiliation: Ecological Engineering Centre, Institute of Natural Resource Sciences, Zurich University of Applied Sciences (ZHAW), Wädenswil, Switzerland; MycoSolutions AG, St. Gallen, Switzerland; Environmental Genomics and Systems Biology Research Group, ZHAW
- Journal: Agronomy (Basel) 13(6) (2023) Article 1436
- Date: 05/2023
- Date added: 2024-02-09
- DOI: 10.3390/agronomy13061436
- Funding: Department of Life Sciences and Facility Management, Zurich University of Applied Sciences, seed grant (Anschubfinanzierung) 2020/21
- URL: https://doi.org/10.3390/agronomy13061436
- PDF:
Gartmann et al. - 2023 - Bioponics—An Organic Closed-Loop Soilless Cultivat.pdf
Opinion
A methodologically careful, well-replicated three-cycle trial (n up to 108 plants/system) with proper ANOVA/Kruskal-Wallis + Tukey post-hoc testing and PCA. Very transparent about the operational difficulty of bioponics (pH swings, EC being useless as a monitoring proxy, salt accumulation). Directly relevant to an aquaponics review only as a conceptual comparator — there is no fish or aquaculture component anywhere in this study; “bioponics” here means biogas-digestate-fed soilless cultivation. Worth citing for the yield-gap and nitrate-accumulation framing, and for its own citation of Nozzi et al.’s ~89% aquaponics-vs-hydroponics yield figure, but should not be miscoded as an aquaponics trial in any pooled analysis.
Abstract
Sustainable food production has become increasingly important. Soilless cultivation systems offer several advantages, such as water and nutrient use efficiency, and can be implemented where traditional agriculture is impossible. Bioponic systems use locally or regionally available nutrient sources from organic waste streams (either fluid or solid) and can thus contribute to closing nutrient cycles locally. Bioponics harnesses the metabolic processes of microorganisms which release nutrients from organic matter. This study aimed to set up a bioponic system, by using biogas digestate concentrate and biochar as nutrient sources, and promoting nutrient release from the organic sources by including a biofilter in the system. The development of water quality, plant growth, and quality was monitored extensively. In addition, the influence of either the fungal biocontrol agent Trichoderma atrobrunneum or UV-C treatment of the nutrient solution on plant health and growth was investigated. Three cultivation cycles with Lactuca sativa (“HAWKING” Salanova®) in bioponic (BP), hydroponic (HP), and soil (SO) cultivation were performed. The study showed that healthy lettuces could be produced in BP systems, using a biogas digestate concentrate and biochar as nutrient sources, despite salt accumulation in the nutrient solution. In plant sap analyses, lettuces cultivated in BP systems contained less nitrate but more ammonium and chloride. The yield of the lettuces grown in the BP systems was intermediate, compared to the HP and the SO. The fungus, T. atrobrunneum, strain, T720, survived in soil and soilless cultivation systems. Compared to the HP and the SO systems, the shoot height of lettuces grown in the BP system, with the application of Trichoderma, was significantly increased. In SO systems with Trichoderma application, a significantly higher chlorophyll and flavonoid content, but significantly lower shoot height was observed. The fresh weight of lettuce roots was significantly higher in HP systems with Trichoderma treatment. Cultivating plants by using organic waste streams requires commitment and experience from producers. In BP systems, a biofilter (either within the system or externally, to increase nutrient levels) can help to rapidly convert the ammonium-rich fertilizer to plant-available nutrients. Unlike conventional HP systems, in BP systems, nutrients are released slowly over time, requiring close monitoring and adjustments. In conclusion, healthy lettuces for human consumption can be produced in BP systems, and the application of the biocontrol agent used has some beneficial influence on plant growth.
Summary
The authors ran three successive 26-day lettuce (Salanova) growing cycles comparing bioponics (BP, nutrient film technique fed with biogas digestate concentrate + biochar, with a dedicated nitrifying biofilter compartment), conventional hydroponics (HP, mineral nutrient solution calculated with HydroBuddy), and soil cultivation (SO, drip-irrigated pots), in a greenhouse at ZHAW Wädenswil, Switzerland. Within BP and HP, some replicate systems were additionally inoculated with the fungal biocontrol agent Trichoderma atrobrunneum and/or given UV-C disinfection of the nutrient solution. They found BP yield was intermediate between HP and SO (about 72% and 66% of HP respectively), BP nutrient solution needed far more active pH and fertilizer management than HP (EC was not a usable proxy for nutrient status because uncharged organic molecules do not register until microbial breakdown), and BP lettuce accumulated markedly less leaf nitrate than HP or SO while containing more ammonium, chloride and silicon. Heavy metals (Cd, Pb) were below detection in all systems. Trichoderma survived in all systems including under UV-C and the BP pH swing from 8 to 4.5, and produced a significant shoot-height increase specifically in BP + Trichoderma versus HP and SO. There is no fish, fish effluent, or aquaculture component anywhere in the study; the organic nutrient source is biogas digestate from a methanization plant (green/catering waste, animal manure, slaughterhouse waste).
Experiment data
- Location: Zurich University of Applied Sciences (ZHAW), Wädenswil, Switzerland (47.21743° N, 8.68151° E), foliar greenhouse
- Design: Three successive 26-day trials (A, B, C); each trial had 4 bioponic (BP), 4 hydroponic (HP), and 2 soil (SO) systems; within BP/HP, 2 systems per trial inoculated with Trichoderma atrobrunneum, 2 given UV-C nutrient-solution disinfection; within SO, 1 system inoculated with Trichoderma, 1 untreated control
- Replicates / n: Plant-level growth parameters n = 108 (BP) / 108 (HP) / 54 (SO) pooled across the 3 trials; yield reported per-trial (n = 3 per system)
- Duration: 26 days cultivation per trial x 3 trials (15 June – 4 September 2020); seedlings raised separately for 27–30 days before transplant
- Organisms: Lactuca sativa “HAWKING” Salanova® (lettuce); Trichoderma atrobrunneum strain T720 (fungal biocontrol agent, not a crop)
- Statistics: Shapiro test for normality; one-way ANOVA (normal) or Kruskal–Wallis (non-normal) with Box–Cox transform where needed; Tukey’s range test / Wilcoxon signed-rank for multiple comparisons; two-way ANOVA for system x treatment interactions; PCA for multivariate structure; R v1.4.1106 (tidyverse, emmeans, rstatix, multcomp, etc.); consumer test analysed in XLSTAT with Friedman test
- Yield: BP 3.09 ± 0.46 kg/m² vs HP 4.26 ± 0.27 kg/m² vs SO 2.83 ± 0.82 kg/m² (Table 6; BP = ~72% of HP, SO = ~66% of HP)
- Leaf nitrate: BP 396.99 ± 274.02 mg/kg fw (lowest) vs HP 598.65 ± 181.63 vs SO 690.29 ± 132.44 mg/kg fw (ZHAW method, mixed leaves, Section 3.3.1)
Not an aquaponics study — scope note
This paper is included in the vault purely as a conceptual comparator, not as aquaponics data. “Bioponics” as operationalised here uses biogas digestate concentrate (anaerobic digestion of green/catering waste, animal manure, and slaughterhouse waste) plus a biochar bag as the organic nutrient source — there is no fish, no aquaculture, and no fish effluent anywhere in the system. The only appearance of “fish” in the entire paper is that commercial Tilapia Vegi fish feed (Hokovit) was used, together with ammonium di-hydrogen phosphate, as a carbon/nitrogen source to mature the nitrifying biofilter for six weeks before each trial started — a one-time biofilter-seeding step, not fish husbandry. The paper’s own introduction explicitly frames aquaponics as one example of the broader bioponics concept (“the best-known example of bioponics is aquaponics… allowing nutrient-rich water from fish production to be used for the fertilization of plants”), and cites aquaponics studies (Nozzi et al., Monsees et al., Graber & Junge) only as literature comparators for yield and nutrient-cycling framing — this paper does not run an aquaponic treatment itself.
Nutrient solution characteristics
This paper: BP had significantly lower dissolved oxygen saturation than HP (96.8 ± 6.6% vs 100.5 ± 2.2%, Table 5) attributed to biofilter biological activity; BP water temperature was significantly higher (23.8 ± 3.5 °C vs 21.1 ± 3.3 °C, by design — heating rods set to 23 °C in BP for nitrifier activity vs 21 °C in HP). pH and EC showed no significant difference between BP (pH 6.9 ± 1.1, EC 846.4 ± 282.5 µS/cm) and HP (pH 7.4 ± 0.4, EC 832.6 ± 212.9 µS/cm), despite BP pH swinging from ~8 at trial start down to ~4.5 within a week — the target pH band (7.0 ± 0.5) was often not held. EC was explicitly reported as not usable as a bioponic nutrient-status proxy because uncharged organic molecules from the digestate do not register on EC until microbial mineralisation begins. BP nutrient solution accumulated Na+, Ca2+, Mg2+, Cl-, SO4²-, and Mn over time (salt accumulation), while HP levels of these stayed constant.
Compared with:
- todo Voogt Holwerda Khodabaks 2011 — desalinisation (reverse osmosis) approach to prevent Na+ accumulation in organic/recirculating solutions, ref. [79] (p.19)
- todo Goddek Delaide Mankasingh Ragnarsdottir Jijakli Thorarinsdottir 2015 — SO4²- release under aerobic conditions in organic nutrient systems, cited as consistent with the SO4²- accumulation seen here, ref. [81] (p.19) — note: this may already be represented in the vault under a different Goddek citekey; check
goddekFullyIntegratedSimulation2019.md,goddekImprovingNutrientWater2020.md,goddekNecessityDesalinationTechnology2018.mdbefore adding a new note
Yield and plant growth
This paper: BP yield 3.09 ± 0.46 kg/m² (n=3 trials), HP 4.26 ± 0.27 kg/m² (c, significantly higher), SO 2.83 ± 0.82 kg/m² (a) — Table 6. Shoot fresh weight: BP 186.5 ± 39.3 g (b), HP 257.7 ± 40.9 g (c), SO 147.6 ± 26.5 g (a) — all significantly different. Shoot dry matter fraction: BP 3.7 ± 0.7% (b), HP 2.9 ± 0.5% (a), SO 3.9 ± 0.5% (b) — BP and SO both significantly higher than HP. Shoot height: BP 15.0 ± 1.9 cm (b), HP 15.4 ± 1.5 cm (b, ns vs BP), SO 12.4 ± 2.3 cm (a). Root-to-shoot ratio: BP 0.10 ± 0.02 vs HP 0.06 ± 0.04 (BP invested more in root growth); root length BP 30.0 ± 9.0 cm (a) vs HP 47.5 ± 13.3 cm (b, significantly longer), yet root fresh weight was higher in BP (18.8 ± 7.2 g, b) than HP (15.9 ± 10.5 g, a).
Compared with:
- todo Williams Nelson 2016 — bioponic yield ~63% of hydroponic control, ref. [21] (p.19, Discussion 4.2)
- todo Atkin Nichols 2004 — bioponic yield ~45% of hydroponic control, ref. [88] (p.19)
- todo Nozzi Graber Schmautz Mathis Junge 2018 — aquaponic yield ~89% of hydroponic control (the closest aquaponics-specific yield-gap comparator cited in this paper), ref. [89] (p.19)
- todo Monsees Suhl Paul Kloas Dannehl Wurtz 2019 — decoupled aquaponic Salanova lettuce, same yield/quality as conventional hydroponics with drastically reduced GHG emissions, ref. [12] (p.2) — directly relevant same-cultivar aquaponics comparator, worth pulling into this vault as a primary source if not already present
- todo Graber Junge 2009 — foundational aquaponics nutrient-recycling-from-fish-wastewater paper, ref. [8] (p.2, p.19)
Food safety — leaf nitrate, ammonium, chloride
This paper: By the ZHAW mixed-leaf extraction method, leaf nitrate was lowest in BP (396.99 ± 274.02 mg/kg fw), intermediate in HP (598.65 ± 181.63), highest in SO (690.29 ± 132.44) — all well under the Swiss (4000–5000 mg/kg) and EU (2500–3500 mg/kg) regulatory limits. By the NovaCropControl plant-sap method (young/old leaves separately, Table 8), BP again had the lowest NO3- and the highest NH4+ and Cl- of the three systems at both leaf ages. See Extraction notes for the ⚠️CHECK on how these two methods’ absolute values relate. Cd and Pb were below detection in all systems/leaf ages (Table 9); Cu and Al showed some significant system differences but no out-of-range food-safety concern was flagged by the authors.
Compared with:
- todo Fallovo Rouphael Rea Battistelli Colla 2009 — comparable high old-leaf nitrate values in HP/SO cited for context, ref. [89 in text, likely mislabelled — verify exact reference number] (p.20)
- todo Blom-Zandstra Lampe 1985 — chloride uptake suppressing leaf nitrate content, mechanism cited to explain BP’s low nitrate / high chloride pattern, ref. [107] (p.20)
Biocontrol (Trichoderma, UV-C)
This paper: T. atrobrunneum strain T720 survived to the end of all trials once inoculated, including under UV-C treatment and through the BP pH crash from ~8 to ~4.5; it could not be detected in un-inoculated systems (presence/absence only — extent of colonisation not quantified). The only significant Trichoderma-driven effect on plant growth reported was a significant shoot-height increase in BP + Trichoderma versus HP and SO. UV-C-treated systems had significantly lower nutrient-solution iron (probably EDTA degradation by UV-C) but no observed plant iron-deficiency symptoms, and higher root fresh weight in HP+UV-C.
Linked claims
- Bioponics uses non-fish organic nutrient sources analogous in function to aquaponics
- Aquaponic and bioponic yields are typically lower than conventional hydroponics
- Organic/bio-based nutrient solutions reduce leaf nitrate accumulation compared to mineral hydroponics
- Electrical conductivity is an unreliable nutrient-status proxy in organic nutrient solutions
Citations to chase
- todo Voogt, Holwerda, Khodabaks (2011) — RO desalination to control Na+ in recirculating/organic nutrient solutions, ref. [79]
- todo Goddek, Delaide, Mankasingh, Ragnarsdottir, Jijakli, Thorarinsdottir (2015) — SO4²- release under aerobic conditions in organic-fed systems, ref. [81]; check against existing vault Goddek notes before creating a new one
- todo Williams, Nelson (2016) — bioponic vs hydroponic lettuce yield (~63%), ref. [21]
- todo Atkin, Nichols (2004) — bioponic vs hydroponic yield (~45%), ref. [88]
- todo Nozzi, Graber, Schmautz, Mathis, Junge (2018) — aquaponic vs hydroponic lettuce yield (~89%), ref. [89]
- todo Monsees, Suhl, Paul, Kloas, Dannehl, Würtz (2019) — decoupled aquaponic Salanova lettuce, same yield as HP with lower GHG emissions, ref. [12] — high-priority, same cultivar
- todo Graber, Junge (2009) — nutrient recycling from fish wastewater by vegetable production, ref. [8]
- todo Blom-Zandstra, Lampe (1985) — chloride uptake suppresses leaf nitrate, ref. [107]
Extraction notes
Scope / classification: type: experiment — three replicated, randomised-enough (systems assigned to BP/HP/SO and to Trichoderma/UV-C sub-treatments), statistically tested (ANOVA/Kruskal-Wallis + Tukey, PCA) trials with the authors’ own original data. Not a review despite extensive literature discussion in the Discussion section (per CLAUDE.md test: has its own Methods, replicates, and statistical tests).
Aquaculture check: No fish, tank, aquaculture, or fish-effluent nutrient loop anywhere in this study. The single mention of fish (commercial Tilapia Vegi feed used to help mature the nitrifying biofilter before trial start) is explicitly a biofilter-seeding aid, not fish husbandry, and is recorded as such — the entire “Fish” block in trials.csv is NA, not NR, per instructions for bioponics-vs-hydroponics papers with no aquaculture component.
⚠️CHECK Leaf nitrate measurement method. Section 3.3.1 (p.17, “According to nitrate analysis (as performed at ZHAW)”): BP 396.99 ± 274.02, HP 598.65 ± 181.63, SO 690.29 ± 132.44 mg/kg fw, described as single mixed-leaf-sample values. Table 8 (p.17, NovaCropControl plant-sap method, young and old leaves reported separately): young leaves BP 983.61 ± 267.07 / HP 1997.79 ± 629.54 / SO 1848.42 ± 1189.95; old leaves BP 1442.923 ± 526.13 / HP 4173.663 ± 470.762 / SO 3010.397 ± 1197.552 mg/kg fw. These are not a contradiction — the paper explicitly names two different labs/methods (ZHAW ion-chromatography extract of a mixed young+old sample vs. NovaCropControl sap analysis of separated young/old leaves) and reports a significant positive correlation between the two methods (Supplementary Table S7, not available in the extracted PDF). Recorded the ZHAW mixed-leaf value in Tissue nitrate AP/Tissue nitrate HYD because it is the paper’s single headline food-safety comparison figure across all three systems in one consistent unit; the NovaCropControl young/old split is fully preserved in plant_measurements.csv (mineral category) instead of being discarded. Affects: nothing else downstream, since both values agree on ranking (BP lowest, HP/SO higher) and both are well under regulatory limits.
Dissolved oxygen unit note (not a contradiction, a schema mismatch): the paper reports dissolved oxygen only as % saturation (Table 5: BP 96.8 ± 6.6%, HP 100.5 ± 2.2%), never as mg/L or ppm. Converting % saturation to ppm requires temperature- and pressure-dependent solubility tables, which would be derivation, not unit conversion — not attempted. Recorded the % value as given in the Dissolved Oxigen cell with an explicit ”% sat, not ppm” annotation rather than leaving it NR, since the paper does report a directly comparable trial-mean value, just not in the schema’s expected unit.
[not reported] fields, grouped:
- Water quality trial means not derivable from time-series-only figures: TAN/NH4-N, NO2-N, NO3-N (Figures 4–5 show only time series across 3 trials with fertiliser-addition events; no single trial-mean ± SD is given for BP or HP for any of these three analytes; text states NO2-N was “for most samplings <0.01 mg/L” — a qualitative floor, not a mean, so left NR rather than invented)
- System design not stated as areal density: Plants/m2 (34 plants/system given, channel geometry given, but no m2 footprint stated — computing density would be derivation)
- Not measured: Leaf count (never scored); SPAD (paper used a Dualex® Scientific meter for chlorophyll/flavonoid/anthocyanin/NBI, not a SPAD meter — not equivalent, and the actual chlorophyll/flavonoid/anthocyanin/NBI values live in Supplementary Table S5, unavailable in the extracted PDF, so plant.csv could not include them — see below)
- Not stated as a rate: Water recycle (L/min), Daily Water exchange rate (%) — refilling was done only to compensate evapotranspiration losses twice weekly, recorded as an amount, not a flow rate or % exchange
- Not categorised by the paper: Water classification, Plant Category (the paper never applies a category label like “leafy vegetable” to the lettuce)
- Not stated as a single combined figure: Average room Temperature — Table 4 gives three separate per-trial greenhouse air-temperature means (24.2, 25.2, 24.0 °C, each significantly different from the others, Kruskal-Wallis a/b/c) rather than one pooled mean across the single row this note represents; recorded
NRrather than averaging the three myself (would be derivation) - Not explicitly stated either way: Artificial Lighting (only ambient greenhouse PAR was monitored; no supplemental lamps mentioned, but absence is not explicitly stated, so
NRnotN)
NO COLUMN items (Experimental Remarks in trials.csv):
- Soil cultivation (SO) arm: yield 2.83 ± 0.82 kg/m², shoot fresh weight 147.6 ± 26.5 g, dry matter 3.9 ± 0.5%, shoot height 12.4 ± 2.3 cm — SO has no dedicated column in the AP/HYD schema (it is neither an aquaponic nor a hydroponic-mineral system); fully described in the note text and included in
plant_measurements.csvasSystem = SOinstead. - Shelf-life: 14-day storage weight retention, no significant differences (BP 83.1 ± 11.1%, HP 79.1 ± 12.8%, SO 81.4 ± 9.6% remaining) — no shelf-life column in schema.
- Consumer acceptance test (47 volunteers, Friedman test + JAR penalty analysis): BP rated comparably to HP/SO overall, scored slightly lower on appearance/taste/texture popularity, “just right” on bitterness, slightly too delicate on crispness — no sensory-panel column in schema.
- Plant sap pH and EC (Table 7, young/old leaves, all three systems) — not water chemistry (this is intracellular sap, not the nutrient solution) and not an elemental/biochemical tissue analyte either, so it fits none of the four
plant_measurements.csvcategories (biochemistry,mineral,microbiology,proximate); values: young-leaf pH BP 6.02±0.07(b)/HP 5.93±0.09(a)/SO 5.91±0.07(a), EC BP 8.37±1.01(b)/HP 6.46±1.14(a)/SO 8.63±1.73(b) µS/cm²; old-leaf pH BP 5.82±0.16/HP 5.84±0.13/SO 5.81±0.11 (ns), EC BP 12.75±1.44/HP 12.12±1.70/SO 11.83±0.58 (ns). - Chlorophyll, flavonoid, anthocyanin content, and NBI (Dualex® measurements) — the paper reports these were measured and significantly differed for some system x treatment combinations (e.g., significantly higher chlorophyll/flavonoid in SO+Trichoderma), but the actual values are only in Supplementary Table S5, which is not part of the extracted PDF and so could not be entered as
NR + reasonper-value in plant.csv rather than fabricated; flagged here instead of silently omitted. - Trichoderma presence/absence data (Supplementary Table S9) and UV-C dose/transmission time series (Supplementary Table S8, Figure S6) are described narratively but their underlying values are also only in the Supplementary File.
Water panel note: the BP/HP nutrient-solution ion panel (Na+, Ca2+, Mg2+, Cl-, SO4²-, Mn, Fe — Figure 5, Table 1) is reported only as time series or as starting/target concentrations (Table 1), never as a trial-mean ± SD table comparable to Table 5’s pH/EC/DO/temperature — per SCHEMA.md this is excluded from trials.csv rather than averaged by hand, and is not plant tissue so does not belong in plant_measurements.csv either. Flagging per SCHEMA.md’s instruction that a water panel “too valuable to discard” should be named in the batch report: this ion panel is fully quantified in Table 1 (starting concentrations) and qualitatively described over time in Figure 5, but has no home in either CSV because it’s neither a trial-mean water-quality value nor a plant analyte.
Judgment calls:
Meta/Plant/Lettucetag applied — Lactuca sativa is the sole crop studied.- No
Meta/Fish/tag applied — confirmed no aquaculture component. Biological system already in usemarkedYfor the biofilter (matured 6 weeks pre-trial);Air supplementmarkedY(air pump + air stone, all systems);Iron supplementedmarkedY(Fe-EDTA added to BP and HP equally);RemineralizationmarkedYfor BP only (biochar bag as P/K/micronutrient source);pH BuffersmarkedY(citric acid/NaHCO3 in BP, HNO3 in HP);Climate controlmarkedYon the basis of the sump heating rods (23 °C BP / 21 °C HP) controlling nutrient-solution temperature — note this is water thermal control, not active greenhouse air climate control (greenhouse air temperature ranged 6.0–45.1 °C across trials per Table 4, suggesting the greenhouse itself was not climate-controlled); recorded as a judgment call rather than leaving the column blank.Replicates (n)recorded as 108 (plant-level growth-parameter n for BP/HP, the more granular of the two n’s given); the trial-level n=3 (used for the areal yield metric in Table 6) is noted here rather than creating ambiguity in a single cell.
Severity tally: 0 ⚠️BLOCK, 0 ⚠️MATERIAL, 1 ⚠️CHECK (leaf nitrate method), 0 ⚠️MINOR → quality: ok (0 BLOCK, ≤2 MATERIAL; CHECK does not count toward the score).
Source: Gartmann et al. - 2023 - Bioponics—An Organic Closed-Loop Soilless Cultivat.pdf
Data Tables
Structured data extracted from this paper into the vault's
trials.csv/plant_measurements.csvdatasets. Fields the paper didn't report are omitted. Download the full datasets (measurements).
Trial Parameters
gartmannBioponicsOrganicClosedLoop2023-T1
Water
| Field | Value |
|---|---|
| Water volume in the system | 255 L total (185 L sump 1 nutrient reservoir + 70 L sump 2 biofilter) |
| Water type | Mixture of tap water and deionized water (1:1), used for BP and HP system filling/refilling |
| Aq pH | 6.9 +/- 1.1 |
| pHOptimal | 7.0 +/- 0.5 |
| Dissolved Oxigen | 96.8 +/- 6.6 % sat (not ppm, see Extraction notes) |
| EC | 0.846 +/- 0.283 |
| Water temperature | 23.8 +/- 3.5 |
Plant
| Field | Value |
|---|---|
| Plant | Lettuce (Lactuca sativa HAWKING Salanova) |
| Details | Pelleted seeds sown in greenhouse; seedlings raised in rockwool cubes 27-30 days before transplant; 3 successive 26-day trials (A, B, C); harvested at trial end |
| Days Plant after transplant | 26 |
| Plant height | 15.0 +/- 1.9 |
| Plant fresh weight | 186.5 +/- 39.3 |
| Plant dry matter | 3.7 +/- 0.7 |
| Tissue nitrate AP | 396.99 +/- 274.02 |
| Tissue nitrate HYD | 598.65 +/- 181.63 |
System & Setup
| Field | Value |
|---|---|
| System type | Bioponic (BP): closed-loop nutrient film technique (NFT), 3 channels in series, sump 1 (nutrient reservoir) + sump 2 (biofilter, nitrification) |
| Media Details | Rockwool cubes (Grodan SBS, 36x36x40 mm) for seedlings; mesh bag with 1 kg alkaline biochar in sump 1; biofilter biochips in sump 2 |
| Biological system already in use | Y (Biofilter (sump 2, 70 L of biochips) matured 6 weeks before each trial using Pure+Filter Start Gel, fed ammonium di-hydrogen phosphate and Tilapia Vegi fish feed (Hokovit) to promote nitrifying bacteria; matured biochips transferred into BP systems at trial start. NOTE: fish feed used only to cultivate biofilter bacteria — no fish were ever stocked or reared.) |
| Air supplement | Y (Air pump with air stone in BP and HP sump reservoirs, dissolved oxygen kept at saturation) |
| Iron supplemented | Y (32 g iron-chelate EDTA-Solution 6.7% (Okohum) added to BP and HP systems at trial start and again after ~10 days, to equalize iron availability between systems) |
| Remineralization | Y (BP only: mesh bag with 1 kg alkaline biochar (~170 mg/kg P, 2730 mg/kg K) placed in sump to supplement phosphorus and micronutrients) |
| pH Buffers | Y (BP: citric acid (>=99.5%) and sodium hydrogen carbonate to hold pH at target 7.0+/-0.5; HP: nitric acid 30% (HNO3) to hold pH at target 6.5+/-0.5; measured and adjusted daily in both) |
| Climate control | Y (Heating rods in sump 2 set to 23 degC (BP) and 21 degC (HP) to control nutrient-solution temperature; this is water thermal control, not documented greenhouse air climate control (ambient greenhouse air ranged 6.0-45.1 degC across trials per Table 4) — judgment call, see Extraction notes) |
| Nutrient supplemented | Y (BP: biogas digestate concentrate (SwissFarmerPower Inwil AG methanization plant; 1/3 each green/catering waste, animal manure, slaughterhouse waste) applied in 3 doses per trial targeting ~50 mg/L TN, plus biochar and Fe-EDTA; HP: fully synthetic mineral nutrient solution (potassium sulfate, calcium nitrate, potassium monobasic phosphate, micromix, Fe-EDTA 6.7%) calculated with HydroBuddy software to the same ~50 mg/L TN target) |
| Equipment | HQ40d portable multimeter with PHC10103 (pH), LDO10101 (DO), CDC40103 (EC) probes (Hach Lange); DR3800 VIS spectrophotometer + LCK cuvette tests (NH4/NO2/NO3/TN/PO4); TOC-L Analyser + ASI-L (Shimadzu); 930 Compact IC flex (Metrohm) for ions; ICP-OES Varian Vista AX CCD (Fe, Mn); Dualex Scientific (ForceA) for chlorophyll/flavonoid/anthocyanin/NBI; 18W Kobre Tec UV-C lamp; HydroBuddy software for HP nutrient calculation; R (tidyverse, emmeans, rstatix, multcomp, etc.) for statistics; XLSTAT for consumer test |
| Control Parameters | 3 successive 26-day trials (A, B, C) in one greenhouse; per trial 4 BP + 4 HP + 2 SO systems; of the 4 BP/4 HP systems, 2 inoculated with Trichoderma atrobrunneum, 2 given UV-C nutrient-solution disinfection; of 2 SO systems, 1 inoculated with Trichoderma, 1 untreated control; target total nitrogen ~50 mg/L TN for both BP and HP (about 1/3 of conventional HP strength) |
| Combination | Bioponics (biogas digestate + biochar, NFT with biofilter) vs hydroponics (synthetic mineral nutrient solution, NFT) vs soil cultivation (drip-irrigated pots); crossed with presence/absence of Trichoderma atrobrunneum biocontrol and presence/absence of UV-C nutrient-solution disinfection; lettuce (Lactuca sativa HAWKING Salanova) as the sole crop |
Site
| Field | Value |
|---|---|
| Region | Europe |
| Country | Switzerland |
| Lat | 47.21743 |
| Long | 8.68151 |
Results & Statistics
| Field | Value |
|---|---|
| Measured Unit | kg/m2 (yield, Table 6); mg/kg fw (leaf nitrate/sap analytes, Tables 7-9) |
| Statistic Details | Shapiro test for normality; one-way ANOVA or Kruskal-Wallis; Tukeys range test / Wilcoxon signed-rank post-hoc; two-way ANOVA for system x treatment; Box-Cox transform for non-normal data; alpha=0.05; R v1.4.1106 |
| Statistically analysed | Y |
| Replicates (n) | 108 |
| AP | 3.09 +/- 0.46 |
| HYD | 4.26 +/- 0.27 |
Experimental Remarks: TRIAL DEFINITION: T1 = pooled bioponic (BP) system data across 3 successive 26-day trials (A,B,C), paired against the hydroponic (HP) control, per the paper’s Tables 5-9 which report BP/HP/SO as system-level means pooled across trials (Trichoderma and UV-C sub-treatments did not differ significantly at the system level per PCA, so are not split into separate rows here; see note file for narrative Trichoderma/UV-C findings). Only one BP-vs-HP row produced; a third arm, soil cultivation (SO), was also tested (yield 2.83 +/- 0.82 kg/m2, ~66% of HP; shoot fresh weight 147.6 +/- 26.5 g; dry matter 3.9 +/- 0.5%; shoot height 12.4 +/- 2.3 cm) but has no column in this AP/HYD schema — recorded as NO COLUMN and fully described in the note file instead. | NOT AQUAPONICS: this paper has no fish, aquaculture, or fish-effluent nutrient loop anywhere. The organic nutrient source is biogas digestate concentrate (anaerobic digestion of green/catering waste, animal manure, slaughterhouse waste) from SwissFarmerPower Inwil AG, not fish waste. The entire Fish block is NA per instructions for bioponics-vs-hydroponics papers with no aquaculture component. The only appearance of fish anywhere is that commercial Tilapia Vegi fish feed (Hokovit) was used, together with ammonium di-hydrogen phosphate, purely to help mature the nitrifying biofilter for 6 weeks before each trial started — a one-time biofilter-seeding aid, not fish husbandry. | WARN-CHECK Tissue nitrate: Section 3.3.1 p.17 (ZHAW method, mixed young+old leaf sample): BP 396.99 +/- 274.02, HP 598.65 +/- 181.63, SO 690.29 +/- 132.44 mg/kg fw. Table 8 p.17 (NovaCropControl sap method, young/old leaves reported separately): young leaves BP 983.61 +/- 267.07 / HP 1997.79 +/- 629.54 / SO 1848.42 +/- 1189.95; old leaves BP 1442.923 +/- 526.13 / HP 4173.663 +/- 470.762 / SO 3010.397 +/- 1197.552 mg/kg fw. Not a contradiction — two different labs/methods explicitly named by the paper, with a stated significant positive correlation between them (Supplementary Table S7, unavailable in extracted PDF). ZHAW mixed-leaf value recorded here as the paper’s single headline food-safety comparison figure across all three systems in one unit; NovaCropControl young/old split recorded in full in plant_measurements.csv (mineral category) instead of being discarded. Both agree on ranking (BP lowest) and both are well under regulatory limits, so no other cell is affected. | UNIT CONVERSION ONLY: EC 846.4 +/- 282.5 microS/cm (Table 5) -> 0.846 +/- 0.283 dS/m (divide by 1000). | Dissolved Oxygen recorded as reported (% saturation, Table 5: BP 96.8 +/- 6.6%), NOT converted to ppm/mg/L — that conversion requires temperature/pressure-dependent solubility tables and would be derivation, not unit conversion; recorded with an explicit percent-sat-not-ppm annotation rather than left NR since a genuine trial-mean value is available, just not in the schema’s expected unit. | NOT DERIVED, left NR: Plants/m2 (34 plants/system and channel geometry given, no m2 footprint stated); TAN/NH4-N, NO2-N, NO3-N as trial means (Figures 4-5 give only time series across fertiliser-addition events, no single trial-mean +/- SD reported for BP or HP for any of the three; text states NO2-N was for most samplings below 0.01 mg/L, a qualitative floor not a mean); Water recycle L/min and Daily Water exchange rate % (refilling only to compensate evapotranspiration, recorded as an amount not a flow rate or %); Average room Temperature as one combined figure (Table 4 gives three separate significantly-different per-trial greenhouse air means: 24.2, 25.2, 24.0 degC — averaging them myself would be derivation). | Replicates (n) recorded as 108 — this is the plant-level growth-parameter n for BP/HP (Table 6 header n = BP/HP/SO 108/108/54); the same table separately gives n=3 per system for the areal yield metric only (one value per trial) — both are explicitly stated for different measures, not a conflict, just different units of replication; noted here to avoid ambiguity in a single cell. | Fish Category, Water classification, Plant Category NR — paper does not categorise beyond naming the fertilizer source and the cultivar. | NO COLUMN: Soil (SO) arm full results (see above). Shelf-life (14-day storage weight retention): BP 83.1 +/- 11.1%, HP 79.1 +/- 12.8%, SO 81.4 +/- 9.6% remaining, ns. Consumer acceptance test (47 volunteers, Friedman test + JAR penalty analysis): BP rated comparably to HP/SO overall, scored slightly lower on appearance/taste/texture popularity, rated bitterness about right, slightly too delicate on crispness, less juicy than HP. Plant sap pH and EC (Table 7, young/old leaves, all 3 systems) — not water chemistry (intracellular sap) and not an elemental/ biochemical tissue analyte, fits none of the 4 plant_measurements.csv categories: young-leaf pH BP 6.02+/-0.07(b)/HP 5.93+/-0.09(a)/SO 5.91+/-0.07(a), EC BP 8.37+/-1.01(b)/HP 6.46+/-1.14(a)/SO 8.63+/-1.73(b) microS/cm2; old-leaf pH BP 5.82+/-0.16/HP 5.84+/-0.13/SO 5.81+/-0.11 (ns), EC BP 12.75+/-1.44/HP 12.12+/-1.70/SO 11.83+/-0.58 (ns). Chlorophyll/flavonoid/anthocyanin/NBI (Dualex measurements) — values only in Supplementary Table S5, unavailable in extracted PDF, so not enterable even as NR+reason per-value; narrative findings only (SO+Trichoderma had significantly higher chlorophyll/flavonoid but lower shoot height). | WATER PANEL EXCLUDED: full BP/HP nutrient-solution ion panel (Na, Ca, Mg, Cl, SO4, Mn, Fe — Figure 5, Table 1) is reported only as time series or as starting/target concentrations (Table 1), never as a trial-mean +/- SD comparable to Table 5’s pH/EC/DO/temperature — excluded from trials.csv per SCHEMA.md rather than averaged by hand; not plant tissue so does not belong in plant_measurements.csv either. Flagged per SCHEMA.md’s too-valuable-to-discard instruction: this panel is fully quantified for starting concentrations (Table 1) and qualitatively described over time (Figure 5) but has no home in either CSV.
Plant Measurements
| Trial | System | Category | Analyte | Value | Unit | Sig. | Location |
|---|---|---|---|---|---|---|---|
| gartmannBioponicsOrganicClosedLoop2023-T1 | BP | biochemistry | Sugar (leaf sap) | 1.16 ± 0.25 | % | ns | Table 7, young leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | HP | biochemistry | Sugar (leaf sap) | 1.45 ± 0.31 | % | ns | Table 7, young leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | SO | biochemistry | Sugar (leaf sap) | 1.38 ± 0.74 | % | ns | Table 7, young leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | BP | mineral | Total nitrogen (leaf sap) | 1328.59 ± 203.19 | mg/kg | ns | Table 7, young leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | HP | mineral | Total nitrogen (leaf sap) | 1243.91 ± 111.01 | mg/kg | ns | Table 7, young leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | SO | mineral | Total nitrogen (leaf sap) | 1169.04 ± 277.61 | mg/kg | ns | Table 7, young leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | BP | mineral | Silicon (leaf sap) | 4.04 ± 1.19 | mg/kg | b | Table 7, young leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | HP | mineral | Silicon (leaf sap) | 0.79 ± 0.33 | mg/kg | a | Table 7, young leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | SO | mineral | Silicon (leaf sap) | 4.79 ± 1.55 | mg/kg | b | Table 7, young leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | BP | biochemistry | Sugar (leaf sap) | 0.39 ± 0.12 | % | ns | Table 7, old leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | HP | biochemistry | Sugar (leaf sap) | 0.41 ± 0.20 | % | ns | Table 7, old leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | SO | biochemistry | Sugar (leaf sap) | 0.55 ± 0.22 | % | ns | Table 7, old leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | BP | mineral | Total nitrogen (leaf sap) | 852.35 ± 191.22 | mg/kg | a | Table 7, old leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | HP | mineral | Total nitrogen (leaf sap) | 1313.95 ± 132.24 | mg/kg | b | Table 7, old leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | SO | mineral | Total nitrogen (leaf sap) | 1022.58 ± 317.54 | mg/kg | a | Table 7, old leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | BP | mineral | Silicon (leaf sap) | 7.85 ± 2.00 | mg/kg | b | Table 7, old leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | HP | mineral | Silicon (leaf sap) | 2.28 ± 1.25 | mg/kg | a | Table 7, old leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | SO | mineral | Silicon (leaf sap) | 8.88 ± 2.74 | mg/kg | b | Table 7, old leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | BP | mineral | Nitrate (NO3-, leaf sap) | 983.61 ± 267.07 | mg/kg | a | Table 8, young leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | HP | mineral | Nitrate (NO3-, leaf sap) | 1997.79 ± 629.54 | mg/kg | b | Table 8, young leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | SO | mineral | Nitrate (NO3-, leaf sap) | 1848.42 ± 1189.95 | mg/kg | ab | Table 8, young leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | BP | mineral | Ammonium (NH4+, leaf sap) | 79.80 ± 32.51 | mg/kg | ns | Table 8, young leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | HP | mineral | Ammonium (NH4+, leaf sap) | 61.78 ± 15.32 | mg/kg | ns | Table 8, young leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | SO | mineral | Ammonium (NH4+, leaf sap) | 49.72 ± 13.97 | mg/kg | ns | Table 8, young leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | BP | mineral | Chloride (Cl-, leaf sap) | 1474.33 ± 229.59 | mg/kg | c | Table 8, young leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | HP | mineral | Chloride (Cl-, leaf sap) | 307.57 ± 69.46 | mg/kg | a | Table 8, young leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | SO | mineral | Chloride (Cl-, leaf sap) | 619.76 ± 171.83 | mg/kg | b | Table 8, young leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | BP | mineral | Nitrate (NO3-, leaf sap) | 1442.923 ± 526.13 | mg/kg | a | Table 8, old leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | HP | mineral | Nitrate (NO3-, leaf sap) | 4173.663 ± 470.762 | mg/kg | b | Table 8, old leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | SO | mineral | Nitrate (NO3-, leaf sap) | 3010.397 ± 1197.552 | mg/kg | ab | Table 8, old leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | BP | mineral | Ammonium (NH4+, leaf sap) | 33.51 ± 5.28 | mg/kg | b | Table 8, old leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | HP | mineral | Ammonium (NH4+, leaf sap) | 25.44 ± 3.35 | mg/kg | a | Table 8, old leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | SO | mineral | Ammonium (NH4+, leaf sap) | 20.70 ± 5.45 | mg/kg | a | Table 8, old leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | BP | mineral | Chloride (Cl-, leaf sap) | 2441.71 ± 414.57 | mg/kg | c | Table 8, old leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | HP | mineral | Chloride (Cl-, leaf sap) | 609.08 ± 232.91 | mg/kg | a | Table 8, old leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | SO | mineral | Chloride (Cl-, leaf sap) | 1087.75 ± 323.12 | mg/kg | b | Table 8, old leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | BP | mineral | Cadmium (Cd) | NR | mg/kg | - | Table 9, young leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | HP | mineral | Cadmium (Cd) | NR | mg/kg | - | Table 9, young leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | SO | mineral | Cadmium (Cd) | NR | mg/kg | - | Table 9, young leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | BP | mineral | Manganese (Mn) | NR | mg/kg | - | Table 9, young leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | HP | mineral | Manganese (Mn) | NR | mg/kg | - | Table 9, young leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | SO | mineral | Manganese (Mn) | NR | mg/kg | - | Table 9, young leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | BP | mineral | Lead (Pb) | NR | mg/kg | - | Table 9, young leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | HP | mineral | Lead (Pb) | NR | mg/kg | - | Table 9, young leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | SO | mineral | Lead (Pb) | NR | mg/kg | - | Table 9, young leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | BP | mineral | Copper (Cu) | 0.65 ± 0.15 | mg/kg | b | Table 9, young leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | HP | mineral | Copper (Cu) | 0.45 ± 0.28 | mg/kg | b | Table 9, young leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | SO | mineral | Copper (Cu) | 0.19 ± 0.07 | mg/kg | a | Table 9, young leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | BP | mineral | Aluminium (Al) | 0.14 ± 0.07 | mg/kg | ns | Table 9, young leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | HP | mineral | Aluminium (Al) | 0.08 ± 0.03 | mg/kg | ns | Table 9, young leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | SO | mineral | Aluminium (Al) | 0.14 ± 0.07 | mg/kg | ns | Table 9, young leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | BP | mineral | Cadmium (Cd) | NR | mg/kg | - | Table 9, old leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | HP | mineral | Cadmium (Cd) | NR | mg/kg | - | Table 9, old leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | SO | mineral | Cadmium (Cd) | NR | mg/kg | - | Table 9, old leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | BP | mineral | Manganese (Mn) | NR | mg/kg | - | Table 9, old leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | HP | mineral | Manganese (Mn) | NR | mg/kg | - | Table 9, old leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | SO | mineral | Manganese (Mn) | NR | mg/kg | - | Table 9, old leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | BP | mineral | Lead (Pb) | NR | mg/kg | - | Table 9, old leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | HP | mineral | Lead (Pb) | NR | mg/kg | - | Table 9, old leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | SO | mineral | Lead (Pb) | NR | mg/kg | - | Table 9, old leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | BP | mineral | Copper (Cu) | 0.42 ± 0.21 | mg/kg | c | Table 9, old leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | HP | mineral | Copper (Cu) | 0.24 ± 0.11 | mg/kg | b | Table 9, old leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | SO | mineral | Copper (Cu) | 0.12 ± 0.03 | mg/kg | a | Table 9, old leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | BP | mineral | Aluminium (Al) | 0.33 ± 0.17 | mg/kg | b | Table 9, old leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | HP | mineral | Aluminium (Al) | 0.13 ± 0.04 | mg/kg | a | Table 9, old leaves |
| gartmannBioponicsOrganicClosedLoop2023-T1 | SO | mineral | Aluminium (Al) | 0.14 ± 0.04 | mg/kg | a | Table 9, old leaves |