Mediterranean Greece · 3 years · two sowing dates
Scientia Horticulturae · 2008
Full-paper technical review
The effect of nitrogen fertilization on plant growth and the nitrate content of leaves and roots of parsley
Across three parsley types, three years and two sowing dates, nitrogen supplied as ammonium nitrate increased foliage and root growth mainly up to about 150 mg N/kg substrate. Raising N to 300–450 mg/kg often produced little or no additional yield but increased nitrate accumulation in leaves and roots.
three parsley types; nitrogen in irrigation water at 30–450 mg N/kg substrate; foliage/root growth and tissue nitrate
Full paper reviewed
The page explains what the independent paper supports and where the evidence may be useful. It does not state that Kumer 1687 uses the same treatment or achieves the same numerical result unless that is documented separately on a Kumer-specific page.
What the full paper actually found
Across three parsley types, three years and two sowing dates, nitrogen supplied as ammonium nitrate increased foliage and root growth mainly up to about 150 mg N/kg substrate. Raising N to 300–450 mg/kg often produced little or no additional yield but increased nitrate accumulation in leaves and roots. The authors therefore identified 150 mg N/kg as the best compromise under their Mediterranean pot/outdoor conditions. This concentration is an experimental substrate treatment, not a kg/ha field recommendation for Kumer 1687.
Full PDF reviewed: 2026-09-09
How this review was built
This page is a technical interpretation of the complete PDF supplied to the Kumer 1687 research library. The abstract was checked against the methods, tables or figures, results and conclusion. Study-specific numbers are kept in their experimental context, and independent research is kept separate from Kumer-specific practice.
- Source authors
- S. A. Petropoulos, C. M. Olympios & H. C. Passam
- Evidence status
- Full paper reviewed
Transfer to Slovenian production
Moderate transferability: the biological or engineering mechanism and the decision logic are useful for Slovenian production, but the exact dose, threshold, timing, machine setting, temperature or shelf-life value must be calibrated locally.
A useful Kumer field validation would compare a small number of nitrogen levels around current practice and measure pre-season/mineral soil N, marketable yield at each cut, tissue nitrate and nitrogen-use efficiency. The experiment should be repeated across at least two soil or seasonal conditions before changing the standard programme.
Local validation before adoption
- Define the commercial endpoint before the trial: marketable yield, grade, freshness, shelf life, water/energy use or labour requirement.
- Compare a control and a test treatment on the same cultivar, field or product lot wherever practical.
- Log the variables that can change the outcome: weather, soil water, product temperature, relative humidity, working depth, crop stage and packaging as relevant.
- Measure benefit and cost/risk together: yield, rejects, crop damage, labour, energy, water and quality.
- Repeat the comparison in at least two relevant production windows or conditions before standardising the practice.
Interpretation boundary
The page explains what the independent paper supports and where the evidence may be useful. It does not state that Kumer 1687 uses the same treatment or achieves the same numerical result unless that is documented separately on a Kumer-specific page.
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Expert interpretation
The decision variable is not maximum nitrogen input but the point at which additional nitrogen stops producing a meaningful marketable-yield response while nitrate accumulation and environmental loss risk continue to rise. The exact optimum must be derived from soil supply, crop uptake, multiple harvests and field losses rather than copied from a pot concentration.
Why this matters to buyers and partners
For buyers, the useful consequence is consistency: nutrition should support marketable leaf yield without unnecessary nitrate accumulation or excessive nutrient input. This paper supports a yield-and-nitrate monitoring approach; it is not evidence that any Kumer batch has a particular nitrate concentration.
Original article
The effect of nitrogen fertilization on plant growth and the nitrate content of leaves and roots of parsley
Scientia Horticulturae · 2008