| Abstract: | A pot experiment was conducted to compare the availability and efficiency of three sulphur (S) fertilisers to wheat in the
first year and oilseed rape in the second year, using six agricultural soils. Four treatments were applied in the initial
year: control (no S), two forms of elemental S (either micronised S° particles or a bentonite + S° mixture) and a sulphate
fertiliser (ammonium sulphate). In the first year, the micronised S° was as effective as the sulphate fertiliser, both producing
similar increases of wheat grain yield (on average 36%) and S uptake (on average 164%) over the control. In contrast, responses
to the bentonite + S° form were minimal, indicating a limited S supply. In the second year the control treatment failed to
produce seeds in most soils, whereas the micronised S° and sulphate treatments increased seed yields of oilseed rape to an
average of 13.4 and 12.9 g pot-1, respectively. The performance of the bentonite + S° varied between soils: two soils produced yields similar to those of
the other S fertilisers, while the remaining soils had low yields. To test whether the poor performance of the bentonite clay
+ S° fertiliser was due to the lack of exposure of the prills to physical weathering in the glasshouse, the effect of freeze-thaw
action on the fertilisers performance was assessed in a separate pot experiment. The responses in wheat yield and S uptake
showed that freeze-thaw did not enhance the physical disruption of the prills or fertiliser effectiveness. These results suggest
that the release of available S from the bentonite + S° mixture was too slow to meet the requirement of wheat and oilseed
rape.
This revised version was published online in June 2006 with corrections to the Cover Date. |
