How Polysulphate performs
Proprietary and independent trials work have shown Polysulphate to be as good as the best sources available of the principal nutrients it contains. It also spreads well at 24 metres and above.
Polysulphate trials have focused on establishing that its principal nutrients – sulphate, potassium, and magnesium – are readily available to the plant. Crop samples were grown in pots and given standard sources of pure potassium and magnesium sulphates, or Polysulphate.
Uptake of the Polysulphate nutrients by the plants was found to be as good if not better than the standard already used in the field. The results confirm Polysulphate’s effectiveness as a multi-nutrient fertiliser.
RELATIVE NUTRIENT UPTAKE FROM POLYSULPHATE COMPARED WITH EQUIVALENT STANDARD NUTRIENT SOURCES AND UNFERTILIZED CONTROL
These trials have been repeated many times over the last ten years, both in pots and in the field. In every case Polysulphate has performed equally well or better than the best standard alternatives.
Field trials in the UK have also investigated the response of cabbage to sulphate fertiliser. The results showed a 40% yield improvement from an application of Polysulphate.
WHITE CABBAGE YIELD RESPONSE TO POLYSULPHATE
(2009 trial on S-deficient site)
Spreadability trials have been undertaken. Polysulphate is a dry, granular 2-4mm product that is available in its natural state. The trials, carried out in France, Denmark and Germany, confirmed an excellent overlapped spread pattern at a 32-metre bout width, with a coefficient of variation of 4.3, and good spreadability up to 36 metres.
SPREADING STRAIGHT POLYSULPHATE
“The apparent recovery of potassium indicates that all of the applied potassium [from the Polysulphate] had been taken up by the grass. Significant effects were also seen with magnesium uptake from the applied fertilizers. Sulphur content in the grass was significantly increased over the control.” Grass pot trial #1, Levington, 1999
“Potassium levels in the grass were significantly lower in the untreated control. There was a rate effect from the Polysulphate, with the full rate being equivalent to the standard treatment. Polysulphate was a good source of sulphur for the grass.” Grass pot trial #2, Levington, 1999
“The results indicate that Polysulphate provides sulphur in an available form immediately after application.” HDRA organic trial, 2001
“The results show that Polysulphate provides an immediately available source of sulphur to spring peas, whereas the S from elemental (90%) sulphur was not being taken up by spring peas over the two-month period following its application to the soil.” Rothamsted trial on spring peas, 2001
“The visual vigor scores at harvest averaged 92 for the Polysulphate treatment compared with 72 for the control without sulphur.” Cabbage field trial, OAT, 2009