Nitrogen and Phosphorus Release from Decomposing Leaves under Sub‐Humid Tropical Conditions<sup>1</sup>
Bibliographic record
Abstract
ABSTRACT For many soils of the tropics, inputs of organic materials are essential to sustain soil fertility and crop production. Research in the quality of organic inputs, a key factor controlling rates of decomposition and nutrient release, continues to guide selection and use of organic materials as nutrient sources. The relationship between decomposition patterns and the quality parameters of the fresh leaves of six agroforestry species:Sesbania sesban, Croton megalocarpus, Calliandra calothyrsus, Tithonia diversifolia, Lantana camara, andSenna spectabilis, was investigated in a litterbag study over a period of 77 days in the highlands of western Kenya. The litterbags were buried 1 cm below the soil surface and covered with soil ofca1 cm thickness. Percent leaf mass and total N and P that remained with time strongly correlated with total P and C/P ratio (R2= 0.60‐0.90) during the first 35 days of study; but afterwards, correlation was stronger with the initial soluble polyphenolics (Pp)/P ratio (R2=0.69‐0.92) than with total P and C/P ratio. Loss of leaf mass and release of N and P followed the exponential function, yt= y0* e‐kt, from which the specific decay rate constants (k) were calculated for loss of leaf mass (kB) and release of N (kN) and P (Kp). Among the plant species, thekvalues were lowest inCalliandrawithkB=0.012/d,kN=0.017/d andkp= 0.044/d.Lantanahad the highest K values withkg=0.067/d andkp=0.119/d, but the highestkNvalue of 0.109/d occurred inTithonia.ThekBvalues for all organic materials were lower than their correspondingkNandkpvalues, suggesting that leaching of N and P from litters may have augmented the microbial mineralization of N and P. There was a strong correlation between thekB, kN, andkpvalues and total P (r = 0.82‐0.96;P0.01), but not total N, lignin (LIG), or Pp. Rates of N and P release followed the general trend:Tithonia > Senna > Lantana > Sesbania > Croton > Calliandra.The results indicated that, among the quality parameters studied, total P is the most important factor controlling rate of decomposition and N and P release from organic inputs in the area of study.
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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) | 0.001 | 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".