Sulphur the forgotten nutrient

Sulphur Deficiency

Sulphur deficiency will typically occur under the following conditions:

• High winter rainfall (leaching of residual S)
• Light or sandy soils
• Low organic matter soils
• Little or no organic material (FYM or slurry) applied
• Insufficient or no inorganic (bagged) sulphur applied

Where silage crops receive sufficient sulphur they will:

• Be of better quality
• Proteins will be higher
• Sugars will be higher
• Conserved silage will be more digestible
• Have a higher total N content but lower free nitrate content having used the available nitrogen more efficiently
• Achieve expected or improved dry matter yields due to efficient utilisation of nitrgoen. Up to 30% average response across all soil types and all cuts is not uncommon
• Be more drought tolerant, displaying improved water retention qualities

All cuts respond favourable to sulphur but especially 2nd and 3rd cuts

Top Tips for...

Soil Chemistry

• Analyse your soils regularly. Of 500 soils recently analysed by ForFarmers advisors, 94% were below target index for Sulphur. Additionally soils not at target pH 6.2 will have reduced availability of P, K and S, so correcting soil pH is key to efficiency

Plan Ahead

• Analyse slurries, test soils and make a nutrient management plan, based on your class of stock, silage quality and yield expectation
• Purchase the correct fertilisers for your needs taking into account manures and the sulphur needs of your silage crops
• Apply in a timely fashion and allow 40kg/ha SOᶟ/cut especially for 2nd and 3rd cut

Measure

• Use fresh grass analysis to monitor N : S levels indicating deficiency or sufficiency
• Plan to correct deficiencies both short and long term

When yield, quality and nutrient efficiencies are considered investment in sulphur for grassand and in particular silage crops will generate a significant return on investment. Recent studies suggest a typical response of up to 30% and as much as £20 return for every £1 spent on sulphur.