Nitrogen leaching and soil nutrient supply vary spatially within a temperate tree-based intercropping system but are unaffected by tree root pruning
Bibliographic record
Abstract
Abstract Well-designed temperate tree-based intercropping (TBI) systems can enhance soil nutrient cycling compared to conventional agricultural systems. To improve the TBI designs and their subsequent wide-scale adoption, greater understanding is required regarding the extent to which widely-spaced tree rows and tree management practices influence spatio-temporal dynamics of soil nutrients. Our two-year study (2021 and 2022) assessed N-leaching and soil nutrient supply at increasing distances from tree rows (0, 4, 12, 20 m); the 10-year-old TBI system (50 trees ha − 1 ) together with agricultural controls was established in southern Québec (Canada). The TBI included hybrid poplars (Populus deltoides × P. nigra) planted alternately with high-value hardwoods in the rows. In each experimental block (n = 3), the TBI system and control were divided into two treatments: without root-pruning vs with (75 cm depth using a sub-soiler). In 2022, NO 3 − supply rates near tree rows (0 and 4 m) were lower than alley centres (12 and 20 m) and controls. A first structural equation modelling (SEM) analysis revealed that NO 3 − supply rates were mostly modulated by indirect effects of tree row distance and soil clay content through volumetric water content (VWC). NO 3 − leaching (40-cm depth) at 0 and 4 m from the tree row was repectively 8.8x and 7.5x lower than that in the control. A second SEM analysis showed direct and indirect (through soil VWC affecting NO 3 − supply rates) effects of distance from tree rows on NO 3 − leaching rates. Within TBI greater tree leaf litter dry-mass was trapped at 0 and 4 m vs 12 and 20 m. P and K availability under tree rows was higher than all other distances within cultivated alleys and control plots. P, K, Ca and Mg supplies within cultivated alleys werer generally similar among distances (4, 12, and 20 m) and did not differ from controls. An unexpected lack of effect of tree root pruning was observed regarding soil nutrient supply and N leaching. Clay content was a major driver of soil nutrient supply and N leaching. The role of TBI systems in determining soil nutrient dynamics depended upon the soil nutrient and sampling period that was measured, with greater effects beneath the trees and at the tree-crop interface.
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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 | 0.003 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.002 |
| 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".