Nitrogen Acquisition of Pea-Oat and Pea-Canola Intercrops and Their Impact on Subsequent Wheat Crops
Bibliographic record
Abstract
The increased diversity provided by intercropping systems can provide many benefits, including increased nitrogen (N) use efficiency (NUE). The ability of legume crops to fix atmospheric N can increase in an intercrop, leading to increased productivity compared to monocrops. However, limited research has tested the efficiency of intercropping systems in western Canada and their effect on subsequent crops. Therefore, pea-oat (PO) and pea-canola (PC) intercrops (mixed row) were grown at Swift Current, Melfort, and Redvers, Saskatchewan followed by wheat in the subsequent year. Each of the intercrops were supplied with three N fertilizer rates (0, ¼, ½ of their recommended rate), while the monocrops (pea, oat, canola) received their full recommendation of N fertilizer, except pea which received no N fertilizer. In the following year, wheat was supplied with its full recommendation of N fertilizer. The 15N dilution method was used to measure the percentage of N derived from the atmosphere (%Ndfa), %N transfer, N fertilizer recovery, and residue recovery in the succeeding wheat crop. The %Ndfa measured the percentage of N in pea that was derived from the atmosphere. In contrast, biological N fixation (BNF) determined the amount of N uptake that was from the atmosphere. The %Ndfa increased in pea intercrops compared to the pea monocrop but due to reduced pea biomass in PO, it decreased the amount of N derived from fixation by 8% compared to the pea monocrop; however, PC increased this amount by 23%, on a per-plant basis. These differences in BNF did not influence productivity, where the intercrops were similar to monocrops. The intercrops produced grain land equivalent ratios (LER) of 0.94 (PO) and 0.98 (PC). In contrast, PC accumulated more above-ground dry matter N than PO and had a 3% advantage over its respective monocrops. This enabled wheat to produce 5% more yield following PC compared to PO but no differences were found between intercropping and monocropping systems. The recovery by wheat of above-ground residue N was higher in monocrops than the intercrops but the low recovery (4%) did not have any impact on wheat yield between the two systems. Overall, PC intercrops appear to be a viable option for producers as they increased BNF, N uptake, and produced slightly higher yields of the following wheat crop than PO. This intercrop also provided comparable intercrop and wheat yields to its monocropping systems; therefore, its ability to utilize N more efficiently made up for reduced fertilizer applications.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| 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".