Northern Sustainable Soils: Leighton Wilksch.
Sulphur deficiency can reduce crop yields.
Additions of sulphate of ammonia and gypsum were tested on crop growth, yield and soil test results in 2015 and 2016.
The aim of the project was to establish sound practices of managing sulphur over a medium-term time frame in both sand dune and clay loam swale environments.
In the field
A trial site was set up at Bute on the northern Yorke Peninsula. The site had low sulphur levels and a dune/swale environment typical of the region.
The initial scope of the project included three years of trials however the first season, in 2014, suffered from several challenges including herbicide damage on lentils, a freshwater soak and a dry finish, leading to limited results and a new site being chosen for the trial in 2015.
Various addition rates of SoA and gypsum were applied to lentils in 2015 and wheat in 2016, with some treatments occurring both years and some only in 2015.
The 2015 season was dry, with a warm spring, which affected all plots. Discussion with nutrition experts Nigel Wilhelm and Mike McLaughlin indicated that the harsh finish may have reduced the nutrition response, with soil moisture limiting crop growth.
In contrast, the 2016 season featured above average rainfall and high yields.
No difference in in-season leaf tissue test results or NDVI (normalized difference vegetation index) measurements were seen from the different treatments
Despite this, all treatments yielded higher than the control in the clay loam swale. There were no significant differences between the gypsum or SoA treatments. In the sand dune, most SoA treatments out-yielded the control, however the gypsum did not significantly increase yield over the control. The highest yielding treatments in the sand dune has SoA applied both years, indicating the residual effect of SoA may not be significant in the sand.
Soil testing in March 2015 showed low initial levels of sulphur. Both treatments increased the sulphur levels compared to the control, with gypsum having more effect in the sand dune while SoA provided more residual sulphur in the clay loam swale.
Value for growers
Key findings in this project have been: