The effect of pH on morphological and physiological root traits of Lupinus angustifolius treated with struvite as a recycled phosphorus source
Bibliographic record
Abstract
Phosphorus (P) recovery from specific waste streams is necessary to develop environmentally sustainable and efficient fertilizers, achieving maximum productivity with minimum losses. A promising example of a P-recovery product is struvite (MgNH 4 PO 4 ⋅6H 2 O). Phosphorus availability from struvite is profoundly influenced by soil pH and/or processes in the rhizosphere. Root exudates (e.g., organic anions) and root morphology affect fertilizer bioavailability. The overall objective of our study was to identify root morphological and physiological traits of the narrow-leaf lupine ( Lupinus angustifolius L. subsp. angustifolius , cultivar: blau “Boregine”) involved in the acquisition of P from struvite, compared with KH 2 PO 4 as a soluble P source. The study included different pH conditions, as soil pH is one of the main factors affecting P availability. Narrow-leaf lupine plants were grown in river sand under three pH conditions (4.5, 6.5 and 7.5). Three different P treatment conditions were used: 1) KH 2 PO 4 (KP); 2) MgNH 4 PO 4 ⋅6H 2 O (Struvite), both supplied at 15 μg P g −1 dry sand; and 3) no P addition (Nil-P), as control. Organic acids in the rhizosheath were collected. Root morphological parameters such as specific root length and root diameter were analyzed. There was no significant difference in total plant biomass detected under any pH condition between struvite and KP treatments. In both acidic and alkaline conditions, the P-uptake efficiency (PUE: mg P plant −1 /cm 2 root surface area) with struvite was significantly greater than with KP. At neutral pH, there was no difference in PUE between plants supplied with KP or struvite. Plants growing at neutral pH showed greater root exudation of carboxylates (mainly citrate) when struvite was added compared with KP. At alkaline pH, the exudation per unit root surface area was greater than that at acidic or neutral pH. Plants growing in acidic pH had a higher specific root length (SRL) compared with those grown at alkaline or neutral pH. Similar P-uptake efficiency from struvite and KH 2 PO 4 at neutral pH in conjunction with the higher total biomass compared to the Nil-P treatment (70% higher) suggests very effective mobilization of P from struvite by carboxylate exudation. Application of struvite, while taking into account the different strategies for nutrient mobilization, can increase the use efficiency of this recovered P source.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".