The importance of early season phosphorus nutrition
Bibliographic record
Abstract
A review of studies conducted in a range of plant species indicated the importance of an adequate supply of P during early crop growth and outlined plant adaptations for accessing early season P. Potential implications of the requirement for early season P in the development of management practices to optimize P supply for crop production were also discussed. Phosphorus plays a critical role in energy reactions in the plant. Deficits can influence essentially all energy requiring processes in plant metabolism. Phosphorus stress early in the growing season can restrict crop growth, which can carry through to reduce final crop yield. Deficiencies during early growth generally have a greater negative influence on crop productivity than P restrictions imposed later in growth. Plants respond to P deficiencies by adaptations that increase the likelihood of producing some viable seed. The adaptations increase the ability of the plant to access and accumulate P and include modification of rhizosphere pH, diversion of resources to root production, increased root proliferation in high-P regions, and formation of associations with vesicular arbuscular mycorrhizae. Plants differ in strategies adopted and in efficiency of P absorption. Effective nutrient management for optimal crop production must ensure that P is supplied to the crop in adequate amounts early in the growing season. It is important that we develop methods to accurately predict the early season P supply from the soil, in order to avoid either over-fertilization or crop deficiencies. Practices to provide adequate P early in plant growth include placement of P fertilizer in or near the seed-row and maintenance of adequate concentrations of plant-available P in the soil through a long-term nutrient management strategy. Other possible management practices could include enhancement of seed concentrations of P, manipulation of tillage system and crop sequence, improved activity of mycorrhizae and other microbiological agents such as Penicillium bilaii to increase phytoavailability of soil P, or genetic selection of crops with an enhanced ability for early season uptake of P from both soil and fertilizer sources. As plants differ in relative abilities to access P from the soil and fertilizer applications, nutrient management must be tailored to the specific crop, in order to optimize P supply and crop productivity. By restricting fertilizer applications to situations where P supply is limiting to crop production and by use of effective P management practices, we can optimize the economic of fertilizer use while avoiding negative impacts on environmental quality. Key words: Crop, fertilizer, placement, nutrient, management
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".