Short-term and long-term effects of tillage and crop rotation on soil physical properties, organic C and N in a Black Chernozem in northeastern Saskatchewan
Bibliographic record
Abstract
A field experiment was conducted for 8 yr (from 1994 to 2001) in a Black Chernozem (Udic Haploboroll) high in organic C (5.5%) at Melfort, Saskatchewan, Canada, to assess the environmental impact of tillage and crop rotation. Short-term effects on residue cover, soil temperature, moisture, aggregation, bulk density and hydraulic conductivity were measured, and long-term effects on total organic C (TOC) and N (TON), and light fraction organic C (LFOC) and N (LFON) were determined. There were two tillage systems [no tillage (NT) and conventional tillage (CT)] and three 4-yr annual crop rotations (canola-wheat-barley-barley,canola-barley-pea-wheat,and canola-pea-flax-barley). Straw was returned to soil every year in all treatments with the exception of flax residue. Soil samples were taken for analysis of organic C and N after the harvest of canola at the end of second 4-yr rotation cycle. Residue cover on soil was higher under NT than CT. Soil temperature was lower and soil moisture was higher in spring, under NT than CT. The proportion of fine aggregates (< 1.3 mm) in soil was lower and that of medium (2.0–12.7 mm) and large aggregates (> 12.7 mm) was generally higher under NT compared with CT. The mean weight diameter (MWD) of aggregates was also larger under NT compared with CT in most cases. The proportion of fine aggregates was higher after canola compared with pea in some cases, but the proportion of medium and large aggregates was higher after pea compared with canola, and in rotations with 50% than 75% broadleaf crops in 2yr. Soil hydraulic conductivity and bulk density were lower under NT than CT in some instances. Compared with CT, NT had greater mass of TOC, TON, LFOC and LFON in soil. However, the differences were significant only for LFOC and LFON, in dicating that light fraction organic C and N was more responsive to NT than CT compared with total organic C and N. In conclusion, the findings suggest that there is no interaction between tillage and rotation, and that light fraction C and N accumulate when tillage is eliminated despite high levels of soil organic C in the soil. Key words: Aggregation, bulk density, crop rotation, hydraulic conductivity, organic C and N, moisture, residue cover soil, temperature, tillage
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| 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".