ATS, KTS and CaTs are liquid fertilizers that supply sulphur alongside one other nutrient. In ATS, that nutrient is nitrogen, in KTS — potassium, and in CaTs — calcium.
The choice between them starts with the crop’s needs and the composition of the overall nutrition programme.
What do the three products contain?
| Product | Nutrient supplied alongside sulphur | Sulphur content |
|---|---|---|
| ATS — ammonium thiosulphate | 12% N — ammonium nitrogen | 26% S |
| KTS — potassium thiosulphate | 25% K₂O — potassium expressed as K₂O | 17% S |
| CaTs — calcium thiosulphate | 6% Ca — calcium | 10% S |
All values are percentages by mass. When comparing specifications, also check the notation: potassium in KTS is expressed as K₂O, while calcium in CaTs is expressed as Ca. Sulphur is shown as S in the table.
ATS: nitrogen and sulphur
ATS supplies ammonium nitrogen and thiosulphate sulphur. It can be used on its own in a nutrition programme or as a component of nitrogen–sulphur blends with UAN.
In these blends, ATS adds sulphur and can slow the conversion of ammonium nitrogen to nitrate. The effect depends on soil conditions and the application method, while the ratio is selected according to the quantities of N and S required. View the ATS specifications.
KTS: potassium and sulphur
KTS is a chloride-free liquid potassium–sulphur fertilizer. It supplies water-soluble potassium and sulphur in thiosulphate form and can complement nitrogen and phosphorus nutrition.
It is an option when the programme needs to include both potassium and sulphur. The product page describes soil application, use through drip irrigation and foliar application, with the relevant restrictions. View the KTS specifications.
CaTs: calcium and sulphur
CaTs supplies calcium and sulphur as part of an overall nutrition programme. Appropriate quantities and application timings are determined by the crop, growth stage, calcium requirement and soil or plant analysis.
It can be applied to the soil, through drip or sprinkler irrigation, or as a foliar application, taking the specific application system into account. View the CaTs specifications.
What does one tonne of product supply?
At the stated nutrient contents by mass:
- 1 tonne of ATS supplies 120 kg N and 260 kg S.
- 1 tonne of KTS supplies 250 kg K₂O and 170 kg S.
- 1 tonne of CaTs supplies 60 kg Ca and 100 kg S.
The same quantity of product therefore supplies different amounts of sulphur and a different accompanying nutrient. Substituting one product for another requires the nutrient balance to be recalculated.
What should we check before mixing?
Compatibility is specific to each product:
- With ATS mixtures must not be acidified below pH 6.
- With KTS and UAN crystals may form, especially in cold conditions. Check the ratio and necessary dilution with a small-scale jar test. KTS must not be acidified below pH 6 either.
- CaTs must not be mixed with phosphate fertilizers, sulphate fertilizers or ATS. This includes APP and nitrogen–sulphur blends containing ATS.
Detailed conditions are described on the product pages for ATS, KTS and CaTs.
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