Evaluation of species selection and management decisions for fall seeded cover crops in Manitoba
Bibliographic record
Abstract
There is limited local research available on cover crops in the eastern Canadian Prairies, including Manitoba. Cover crops are an agronomic practice in which plants are used to cover the soil for ecosystem benefits, rather than for market. Cover crops are often seeded and managed outside the conventional growing season, as to not displace cash crops. Ecosystem benefits (e.g. soil erosion control, N retention, weed suppression) can only be realized when there is sufficient cover crop establishment and growth. Cover crop performance depends on the overlapping influences of species selection and management decisions made in the context of a particular location. The limitations of GDD accumulation and precipitation amounts and timing in Manitoba present unique challenges when making cover crop decisions. The objective of this thesis was to compare cover crop decisions and to evaluate how these decisions affected the performance of different fall seeded cover crops in Manitoba. In addition, the impact of fall seeded cover crops on following cash crops was determined. This was achieved through three research studies. The first research study compared seven cover crop species, plus one mixture, seeded at three different dates in the fall. Two site-years were dry and two site-years were wet. Emergence, biomass production, C:N ratio, and ground cover were similar between winter killed cool season cover crop species when seeded around September 1. The second research study evaluated the effects of fall seeded cover crops on a spring wheat (Triticum aestivum L.) test crop. Three cool season annuals, one winter annual, and one cover crop mixture were seeded in the fall. Winter killed cover crops had no effect on the test crop. Fall rye (Secale cereale L.) and the mixture that contained fall rye had a negative effect on wheat density and wheat yield. The third research study compared fall rye cover crop termination timings prior to soybean (Glycine max (L.) Merr.) and edible bean (Phaseolus vulgaris L.). Managing the living cover crop in the spring with strip tillage removed the soybean yield penalty caused by late fall rye termination but only slightly improved edible bean yield. These results highlight the opportunity for using winter killed fall seeded cover crops in Manitoba with minimal risk to a following small grain crop. Fall rye used as a cover crop prior to spring wheat and edible bean requires termination prior to planting. Soybean can be planted green into fall rye with strip tillage. Results from this research show that there are opportunities for fall seeded cover crops in Manitoba cropping systems and will provide guidance for cover crop decision making. Future research under these environmental conditions should explore cover crop performance and thresholds for ecosystem benefits in Manitoba.
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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 | 0.001 | 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".