Long-term nitrogen, phosphorus and potassium fertilization of cassava influences soil chemical properties in North Vietnam
Bibliographic record
Abstract
The long-term effects of yearly fertilizer applications on soil chemical properties and nutrient availability are not well documented for cassava (Manihot esculenta) production in Vietnam. In 1990, research plots were established (randomized complete block design) with 12 treatments to test effects of different rates of N, P and K on soil properties in Acrisols (FAO-UNESCO Soil Classification) at Thai Nguyen University, North Vietnam. In June 1998, composite soil samples (0- to 10-cm and 10- to 20-cm depth) were collected from each plot. Nine years of N application significantly reduced the labile pools of soil inorganic P, total soil P and soil extractable K and Mg. Total soil N was only slightly increased in the 10- to 30-cm depth. Long-term applications of P significantly increased soil inorganic P fractions, but reduced concentrations and supply rates of nitrate and K. Moreover, 9 yr of K application significantly increased soil organic C (two depths), soil total N (10-30 cm) and soil extractable K in the 0- to 10-cm depth. Generally, the results show that long-term applications of mineral fertilizers in a ratio of N:P2O5:K2O of 2:1:2 (at the rates of 80 N:40 P2O5:80 K2O or 160 N:80 P2O5:160 K2O) are effective in maintaining the total content and availability of applied nutrients, but when applied alone are associated with decreases in other nutrients. Key words: Nitrogen, phosphorus, potassium fertilizers, cassava, ion exchange resin, soil properties
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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 | 0.000 | 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 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".