Spatial and temporal trends in soil properties and crop yield at a site under intensive up- and down-slope potato production in northwestern New Brunswick
Bibliographic record
Abstract
Few quantitative data are available to assess temporal changes in the soil quality of Canada’s agricultural lands. Site 20-NB was established in 1989 to monitor changes in an Orthic Humo-Ferric Podzol developed on coarse loamy till on a rolling landscape under intensive potato production in Atlantic Canada with soil compaction and water erosion the dominant forms of degradation. Sampling of soil and crop parameters was conducted on a 20 × 25 and 25 × 25 m grid basis with 66–90 sample locations. Baseline soil samples were collected in 1989 and the site was re-sampled in 1999. Samples were analysed for pH, available P, K, Ca and Mg, and total soil organic carbon (SOC). Field saturated hydraulic conductivity (Kfs) at 12–22, 27–37 and 50–60 cm, earthworm counts and crop yield measurements were conducted annually. 137Cs data were collected to estimate long-term soil erosion. Annual runoff (May 01 to Nov. 30) and soil loss were measured. Seasonal soil loss between 1989 and 1999 was only 6522 kg ha-1 yr-1 compared with 137Cs-estimated soil displacement of 53 000 kgha-1 yr-1, occurring over the 1960 to 1990 period. In the Ap horizon, soil pH and P increased by 8 and 5%, respectively, while SOC was reduced by 8%. Some changes were identified in the subsoil (50–65 cm) with a 7% increase in pH and a 27% reduction in P. There was little annual variation in the Kfs of the Ap, B and C horizons which ranged from 0.4 to 1.3, from 0.7 to 1.3 and from 0.8 to 2.0 cm h-1. Solum Kfs was significantly less than in an adjacent forested area by 52–80%. Earthworm numbers increased at a rate of 1.5 earthworms m-2 yr-1. Crop yield did not show any temporal trend over the 10-yr period other than that it appeared to be significantly influenced by crop rotation. Potato yield (CV = 12) tended to be less variable than barley (CV = 22) or clover (CV = 21). The benefits of site specific management were found to be questionable. 137Cs-estimated soil loss was most strongly related to SOC (r = −0.66) and average potato yield (r = −0.55). Key words: Soil quality, soil carbon, hydraulic conductivity, earthworms, water erosion
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 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".