GranAm® offers versatility to combat sulphur deficiencies in pastures

Author: Reily Menhenett, Technical Agronomist, Incitec Pivot 

Key messages 

• GranAm® offers an opportunity to top up sulphur, alongside winter or spring applications of nitrogen. 
• Annual maintenance of sulphur is 12kg/hectare 
• Where hay and silage are cut, a further ~2kg/ha of S will be removed. 
• Close to 50% of soil tests have below optimal soil sulphur (KCl) across Victoria and South Australia. 

For pastures in Southern Australia, sulphur (S) is often a forgotten nutrient, with excess typically being applied with autumn applications of SuPerfect®. However, with a dry 2025 followed by decile 10 prices for Single Super in 2026, many growers may have gone consecutive seasons without topping up S levels.  

Soil test snapshot 

For pastures, a soil test result (sulphur KCl40) 10-20mg/kg of S is considered optimal. However, of the more than 2,000 pasture soil test samples submitted to Nutrient Advantage in the last year from southern pasture areas (Figure 1): 

• 3% were at a critical level 
• 13% were very low 
• 29% were low 

Meaning that 45% of paddocks had a sub-optimal sulphur level. Only 36% of samples had an adequate sulphur level. 

^{Figure 1: Sulphur results from more than 2,000 pasture soil test samples submitted to Nutrient Advantage from June 2025 to June 2026.}  

Role of GranAm®  

GranAm® is Incitec Pivot’s granulated ammonium sulphate fertiliser, providing superior blending compatibility and spreadability when compared to crystalline forms. GranAm® contains 21% nitrogen (N) and 24% S by weight, making it a perfect substitute for straight urea in a N topdress, where S is necessary. GranAm® can be applied as straight S where S is critically deficient, or in a blend with urea to balance both N and S.  

Emerging from winter and into spring, keeping S levels topped up will ensure growers can get the most out of their spring flush. Using blends such as GrassBoosta (30-0-0-15) can be an ideal way to supply necessary N with supplementary S to fast-growing pastures.  

Figure 2 highlights an example of Gran Am providing an additional dry matter benefit compared to urea, in a mixed sward near Hamilton in 2025.  

^{Figure 2: Dry matter comparison urea vs GranAm® topdressed on a mixed pasture sward near Hamilton (2025). 50kg/ha of N was supplied as urea or GranAm® in June, and dry matter was assessed in August.}  

Reduced volatilisation risk 

Compared to urea, GranAm® has a lower risk (~60% in most soils) of volatilisation, due to the acidic nature of the granule, compared to the localised alkalinity caused by a urea granule.  

For organic carbon percentage and thatches can intercept granules before they reach the ground, meaning volatilisation can be a substantial N loss pathway.  loss pathway.  

^{Figure 3: Volatilisation of urea compared to GranAm®. Source (Incitec Pivot Fertilisers Southern Volatilisation trials 2024-25).} 

Summary 

GranAm® can be an excellent substitute or partner for urea this season, either for winter pasture topdress, or moving into spring applications.  

Don’t let low S hold back your pasture’s production. 

For more information, contact Reily Menhenett on 0474 093 167 or email: .