Sulfur is an essential nutrient, but how much do we need?
Canola is often regarded as having a high requirement for sulfur (S), but does it?
Analysis of plant tissue samples and a lack of response in most CSBP canola trials indicates that deficiencies are rare. And analysis of canola grain from many trials shows that S removal rates are not as high as often thought.
CSBP has tested for S responses in thirteen canola trials since 2008 (Figure 1). Of these, only two have produced yield responses (Manypeaks, 2010 and Cunderdin, 2017). Both sites had very low levels of S in the top 30 cm of soil (2 mg/kg), and plant testing confirmed deficiencies.
Figure 1. Canola yields with and without sulfur applications in CSBP trials 2008 – 2018. Trials marked * denote a significant response.
High yields (3.5 t/ha) were grown at Condingup (2008) and Mount Barker (2018) without any S applied!
Analysis of seed also indicates that many Growers are over-applying S with only about 4 kg of S being removed in every tonne of yield.
Sulfur is an essential nutrient, but applications are often excessive and an unnecessary cost.