Phosphorus fertilization and mycorrhizae influence soil phosphorus dynamics, corn nutrition and yield under reduced-tillage practices
Bibliographic record
Abstract
Grain corn (Zea mays L.) production occupies more farmland than any other annual crop in Quebec and is expanding demand from the livestock sector and the emerging bioethanol industry. Corn production requires high nutrient inputs and intensive tillage (IT). Many producers have thus switched to conservation tillage systems like ridge-tillage (RT) to overcome soil compaction and erosion problems that are common in IT systems. However, fertilizer guidelines developed for IT soils are used in RT although RT adoption greatly modifies phosphorus (P) dynamics. Lower fertilizer P requirements are expected because arbuscular mycorrhizal (AM) symbiosis known to enhance plant P nutrition are minimally disrupted under RT, compared to IT systems. A two-year study was conducted on a commercial farm in the Monteregie region (Quebec, Canada) to investigate the effects of P fertilizer rates and soil P-saturation status on corn early growth, nutrition and yield. Surface soil plant-available P was monitored in situ with anionic exchange membranes (P AEM) from seeding to the end of July. The effects of indigenous AM fungi on corn parameters and rhizosphere soil P pools were also investigated in untreated (AMNI) or AM-inhibited fungicide-treated (AMI) soils. Quebec's P fertilizer guidelines underestimated the soil P fertility in studied soils. Adding inorganic P (Pi) did not improve the early corn P nutrition, growth or yield, and had little impact soil PAEM. Variations in PAEM were better explained by climatic variables. AMNI corn had similar early development and high yield, regardless of whether P fertilizer was applied, whereas AMI plants needed P fertilizer to produce optimal yield. AMNI corn had reduced dependence on Pi inputs due to more efficient uptake of soil solution P i in surface and rhizosphere soils during the first 22 days after seeding (DAS), In the rhizosphere, available-Pi pool appeared to be used first to replenish the resin-P pool, but over the longer term, AM symbiosis also enhanced NaHCO3-Po mobilization through a mechanism that remains unclear. Deeper understanding of the mechanisms by which AM fungi alter soil P dynamics will contribute to the development of more sustainable P fertilizer programs for RT systems.
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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 | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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".