Is Sulphur Lacking in Your Swards?

Sulphur is an important element for plant growth and development.  It impacts on dry matter yield and protein levels in grass.  Sulphur has a close interaction with Nitrogen.  The aim should be to have an N:S ratio of 13:1.  Most detailed soil analysis will provide you with this information.

Sulphur is very mobile within the soil.  Sandy and shallow soils are particularly prone to sulphur deficit.  Loamy soils where rainfall between November and February is >200 mm or clay soils with rain >400 mm in the period is also prone to deficiency.

When discussing fertiliser requirements many people are surprised how much sulphur is actually required.  The more nitrogen you apply the more sulphur is needed.

• Silage fields require 40 kg SO₃/hectare before each cut on soils at risk of sulphur deficiency, see above.
• Grassing fields require 20 to 30 kg SO₃/ha per 100 kg N/ha applied, e.g., apply 34.5%N fertiliser at 580 kgs/ha total during the grazing season would require between 40 and 60 kg SO₃/ha.

Sulphur can be applied in three main ways; organic manure/slurry, compound fertiliser, e.g., single or double top, or a sulphur fertiliser, e.g., Gypsum which is 40% SO₃.  Normally a combination of two or three of these options are used depending on your fertiliser regime and what organic manure/slurry is available.\

The potential benefits of correcting any sulphur in balances in the soil are increases of up to 25% in dry matter yield and up to 4% in protein levels.  These can lead to reduced concentrate costs as lower protein levels can be used as well and increased output of forage per hectare.

To discuss your fertiliser plans for 2023 and see where savings can be made whilst ensuring production is optimised, contact Phil Cooper FACTS at pcooper@fcgagric.com  or Tel: 07798 673665.