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Copy link Polysulphate Onion Trial in Turkey
51
Antalya, Turkey 2016
51
Key Conclusions
This trial demonstrates how profitable Polysulphate fertilizer is for onions. Polysulphate application increases onion bulb yield by 51%, and vitamin C content by 23%.
Objective
To investigate the effect of Polysulphate, potassium sulfate (SOP) and potassium chloride (MOP, KCl) on the yield, quality parameters, and nutrient uptake of onion (Allium cepa).
Trial Details
Trial station
Antalya, Turkey
Crop
Onion
Product
Granular Polysulphate
Assessments
Bulb yield, quality parameters, and nutrient uptake
Treatments
This randomized trial consisted of 4 replicates with 5 treatments. Nitrogen, phosphorus, and potassium were applied, according to target yield and soil tests, at a rate of 200 kg N/ha (as urea and diammonium phosphate, DAP), 170 kg P2O5/ha (as diammonium phosphate, DAP) and 270 kg K2O/ha (as Polysulphate, SOP or MOP). An additional treatment consisted of K given as 50% from SOP and 50% from Polysulphate. The control treatment received the same N and P doses, but no K was applied.
| Treatment | N | P2O5 | K2O | S | MOP | SOP | Polysulphate |
|---|---|---|---|---|---|---|---|
| kg/ha | kg/ha | kg/ha | kg/ha | kg/ha | kg/ha | kg/ha | |
| Control | 200 | 170 | 0 | 0 | - | - | - |
| MOP | 200 | 170 | 270 | 0 | 443 | - | - |
| SOP | 200 | 170 | 270 | 97 | - | 540 | - |
| Polysulphate | 200 | 170 | 270 | 370 | - | - | 1,928 |
| SOP + Polysulphate | 200 | 170 | 270 | 234 | - | 270 | 964 |
Treatments
This randomized trial consisted of 4 replicates with 5 treatments. Nitrogen, phosphorus, and potassium were applied, according to target yield and soil tests, at a rate of 200 kg N/ha (as urea and diammonium phosphate, DAP), 170 kg P2O5/ha (as diammonium phosphate, DAP) and 270 kg K2O/ha (as Polysulphate, SOP or MOP). An additional treatment consisted of K given as 50% from SOP and 50% from Polysulphate. The control treatment received the same N and P doses, but no K was applied.
| Treatment | N | P2O5 | K2O | S | MOP | SOP | Polysulphate |
|---|---|---|---|---|---|---|---|
| kg/ha | kg/ha | kg/ha | kg/ha | kg/ha | kg/ha | kg/ha | |
| Control | 200 | 170 | 0 | 0 | - | - | - |
| MOP | 200 | 170 | 270 | 0 | 443 | - | - |
| SOP | 200 | 170 | 270 | 97 | - | 540 | - |
| Polysulphate | 200 | 170 | 270 | 370 | - | - | 1,928 |
| SOP + Polysulphate | 200 | 170 | 270 | 234 | - | 270 | 964 |
Results
- Plant total uptake of N, P, K, Ca, Mg, and S were highest in the Polysulphate treatment. Also, micronutrient uptake (Fe, Zn, Mn, and Cu) was significantly increased by Polysulphate application.
- Nutrient concentration in the bulb (P, K, Ca, Mg, S, and Fe) were highest with the Polysulphate treatment.
- Polysulphate treatment resulted in the highest bulb yield significantly differing from the other treatments. Also, bulb weight, bulb height, and bulb diameter were highest with the Polysulphate treatment.
- Polysulphate application increased the net return and was very profitable, with a B:C (benefit:cost ratio) of 21.2.
- The highest vitamin C concentration was found in the Polysulphate treatment. Polysulphate also increased antioxidant activity, phenols concentration, and total soluble solids (TSS), which are very important quality parameters for onion.
Polysulphate significantly increased onion bulb yield by 51%.
Polysulphate significantly increased onion Vitamin C content by 23%.
Different letters above bars indicate significant differences among treatments (p<0.001).
From research funded by the International Potash Institute www.ipipotash.org
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