SILARA N30 / Evaluation pathway / Updated 24 September 2026
What a three-season Polish field experiment tells us about foliar sodium metasilicate, early potato yield and tuber quality, with the complete 2023 paper available to read and download.
Published research is not demonstrated SILARA N30 performance. This experiment used Optysil, a sodium-metasilicate product that also supplied iron chelate, on the very early cultivar ‘Catania’. It did not test SILARA N30. The results support local evaluation; they do not establish a SILARA N30 potato rate, yield guarantee or quality claim.
01 / Identify the evidence
One field experiment, complementary reports
Wadas (2023), Nutritional Value and Sensory Quality of New Potatoes in Response to Silicon Application, primarily reports tuber composition and after-cooking darkening. Its Section 3.1 summarises yield findings from the earlier Wadas (2022) yield report. Both describe the same 2016-2018 field experiment, not two independent trials.
Field conditions
One experimental site in central-eastern Poland; sandy-loam Haplic Luvisol, pHKCl 5.2-5.7. The very early cultivar ‘Catania’ was harvested 75 days after planting. Conditions varied from periodic water deficits in 2016 to a wetter 2017 and a very dry 2018.
Design and samples
A two-factor split-plot design compared two doses and three timings with water-sprayed controls, in three replications. Plots were 16.2 m² with 96 plants. Quality testing sampled 50 mixed-size tubers per plot; 10 tubers were scored for after-cooking darkening. These tubers were subsamples, not additional independent field replications.
02 / Results depend on season
Early total-tuber yield increased in two seasons
The published text reports the following average changes across Optysil treatments versus the control. These are total yield figures, not marketable yield, and should not be attributed specifically to the 46.5 g Si/ha rate.
| Season | Growing conditions | Reported result |
|---|---|---|
| 2016 | Periodic water deficits | +4.94 t/ha (+23%) |
| 2017 | Relatively wetter | No significant difference in the 2022 report’s Figure 1 |
| 2018 | Very dry | +2.43 t/ha (+13%), as stated in the Results text |
Source: 2023 paper, Section 3.1, and 2022 report, Results and Figure 1. The 2016 and 2018 numbers reproduce the published text; they are not recalculated from graph heights. Shared letters in the 2017 total-yield panel indicate no significant difference at p ≤ 0.05.
The earlier report separates marketable tubers (diameter above 30 mm) from total yield. Its marketable-yield response must not be substituted for the total-yield percentages above. Timing also mattered: the authors favoured the higher dose at tuber initiation under periodic deficits and two lower-dose sprays under drought. These observations are not a SILARA N30 recommendation.
03 / Read the quality findings as well
Starch responded; most measured quality traits did not
Across three years, mean tuber starch was 117.3 g/kg fresh weight in the control and 121.1 g/kg with Optysil, a difference of 3.8 g/kg. When years were analysed separately, the significant increase occurred only in the very dry 2018 season: 14.5 g/kg fresh weight above the control. This is a concentration difference, not a 14.5% yield gain.
No significant overall treatment effect was found for dry matter, total sugars, monosaccharides, protein, L-ascorbic acid (vitamin C), nitrate content or after-cooking darkening. Some timing comparisons within treated plots differed; these do not establish an overall improvement versus the control. The study did not demonstrate that all nutritional or sensory qualities improved.
Source: 2023 paper, Tables 2-5 and 8, Figure 1, and Sections 3.2-3.3. Statistical comparisons used Tukey’s test at p ≤ 0.05. Read the quality results in the complete paper.
04 / Formulation, dose and frequency
46.5 g elemental Si/ha was the higher dose per spray
The paper describes Optysil (Intermag) as containing 93 g elemental Si/L as sodium metasilicate and 24 g Fe/L as Fe-EDTA. Treatments were applied once at leaf development (BBCH 14-16), once at tuber initiation (BBCH 40-41), or at both stages.
| Programme | Product/ha | Elemental Si/ha | Iron/ha |
|---|---|---|---|
| One lower-dose spray | 0.25 L | 23.25 g | 6 g |
| One higher-dose spray | 0.50 L | 46.50 g | 12 g |
| Two lower-dose sprays | 0.50 L total | 46.50 g total | 12 g total |
| Two higher-dose sprays | 1.00 L total | 93.00 g total | 24 g total |
For mass comparison, 46.5 g elemental Si × (60.084 ÷ 28.085) is approximately 99.5 g SiO₂-equivalent. The earlier yield report describes the same formulation as 200 g SiO₂/L; the small arithmetic difference reflects the rounded formulation values. Elemental silicon and silicon dioxide are not interchangeable units.
Similar gross mass is not an equivalent programme. SILARA N30 is an amorphous colloidal silica concentrate, and its typical pasture rate is 300 mL/ha. A reliable mass comparison also requires the verified concentration basis and, for a weight percentage, product density. The potato papers do not establish those SILARA N30 inputs, equivalent availability, uptake or efficacy. The pasture rate is not validated as a potato rate by this research.
Optysil also supplied iron. No iron-only control was included, so the measured response cannot be assigned to silicon alone.
05 / New Zealand evaluation pathway
Build product-specific evidence before making crop claims
A local SILARA N30 trial should establish crop safety, rate, timing and compatibility under a defined programme. Use replicated treated and untreated plots under otherwise matched management, with records of cultivar, soil, fertility, rainfall, irrigation and application conditions.
Measure total and marketable yield separately, size-grade distribution, dry matter, starch and crop injury; assess commercial returns using actual inputs and saleable output. This single-cultivar, single-site early-harvest experiment does not establish results for New Zealand maincrop or processing potatoes.
Full paper and references
Wadas, W. (2023). Nutritional Value and Sensory Quality of New Potatoes in Response to Silicon Application. Agriculture 13(3), 542. doi:10.3390/agriculture13030542.
Read or download the original 11-page article. The PDF includes the complete methods, figures, tables, references and licence. It is the unchanged file supplied for this research page.
Related yield report: Wadas, W. (2022). Possibility of increasing early crop potato yield with foliar application of silicon. Agronomy Science 77(2), 61-75. doi:10.24326/as.2022.2.6. This reports the same field experiment.
Original 2023 article © Wanda Wadas; published by MDPI under CC BY 4.0. The original PDF is unchanged. This Bio Charge webpage and linked summary are adaptations; no author or publisher endorsement of Bio Charge or SILARA N30 is implied.