Solubility of soil phosphorus in extended waterlogged conditions: An incubation study
Bibliographic record
Abstract
Understanding how extended excess soil moisture exacerbated by extreme weather events affects changes in iron (Fe) chemistry is crucial for assessing environmental risk associated with soil phosphorus (P) in high P soils. The objective of our study was to assess the effects of three soil moisture regimes (field capacity, water saturation, and waterlogging), two Fe 3+ nitrate level (Fe 3+ nitrate addition and no Fe 3+ nitrate addition), and the duration of incubation (0, 3, 7, 14, 21, 28, 35, 49, 63, 90, and 120 days) on the (i) reduction of ferric (Fe 3+ ) to ferrous (Fe 2+ ) iron, (ii) solubility of soil P, and (iii) soil microbial biomass and greenhouse gas emissions. Surface soils (0–20 cm) were collected from a maize silage field located in the Fraser Valley (British Columbia, Canada). Decreased redox potential (Eh) of 155 mV in waterlogged soils coincided with the reduction of Fe 3+ to Fe 2+ of about 1190 mg kg −1 and an increase in soil pH of 0.8 unit compared to field capacity regime at 120 days after pre-incubation ( P < 0.001). The increase of pH is due to the microbially-mediated reduction of metal cations which consumes H + cations. Water-extractable P (Pw) concentrations increased with increasing soil moisture regimes from 1.47 to 2.27, and 2.58 mg kg −1 under field capacity, water saturation, and waterlogged regime respectively. Mehlich-3 extractable P concentrations significantly decreased from 196 to 184 and 172 mg kg −1 under water saturation, field capacity, and waterlogged regime respectively. Concomitant to Pw concentrations, microbial biomass carbon and nitrogen as well as DOC, CO 2 and N 2 O emissions increased with increasing soil moisture regimes. The Fe 3+ nitrate addition had an inhibitory effect on Fe reduction, Pw concentration at the first 35 days, and DOC but a stimulating effect on N 2 O emission. A high N 2 O emission at the first 63 days, CO 2 emission after 35 days, and a non-remarkable concentration of Fe 2+ at the first 63 days with Fe 3+ nitrate addition under waterlogged soil suggests that NO 3 − is more preferable than Fe 3+ as an electron acceptor. Our results showed that soils maintained under extended anoxic conditions could increase the soluble and available P and subsequent risk of P transport to surface and drainage waters, whereas Fe 3+ nitrate addition could minimize or delay this effect.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".