Pollution crackdown has left grassland short of sulphur

For the all-important second cut, this can really make a difference to the bottom line.

It’s widely recognised that the amount of sulphur available to grass crops is decreasing, therefore applying sulphur-containing fertilisers can induce a marked yield response in silage crops.

Independent trials from 2016 in Cheshire have demonstrated that second cut silage crops, treated with a CF Fertiliser containing sulphur, returned an additional 1.5 DM/ha yield. This equates to replacing one tonne of concentrate, as it provides enough energy to produce an extra 2,000 litres of milk.

On paper, it’s a no-brainer, but generally sulphur application to grassland has never been a habit, as historically sulphur was supplied by atmospheric deposits as a by-product of industrial activity.

In the 1960s and 1970s, between 70 to 80 kg/ha of sulphur was deposited onto agricultural land from the atmosphere, which meant there was little need to apply it to crops. However, with a clampdown on industrial emissions, deposits were reduced to less than 5 kg/ha in the early 2000s.

It’s now a given that most grassland is deficient in sulphur and that there’s a need to use sulphur-containing fertilisers on grassland in many parts of the UK, to see big differences to dry matter yields.

In the past, a debate has arisen over copper-sulphur lock-up in the soil. However, this likelihood has become extremely low due to the reduction of atmospheric sulphur deposits.

The amount of sulphur contained in compound fertilisers is not enough to push sulphur levels in the soil to excess, as they are designed specifically to meet the needs of the crop. This is because they contain key nutrients in each granule, which produces an even spread across all the landing sites when applied.

For farmers using their own nutrients, such as farmyard manure and slurry, on their grassland, a combined nitrogen sulphur product like SingleTop (27.0.0+12SO3), for example, can be used in conjunction with the manure applications to deliver the much needed sulphur, balanced with the necessary organic nutrients.

Everyone’s situation is different, so you’re best to get specialist advice and ensure your nutrient plan is delivering your crops requirements.

David Mitchell is Wynnstay fertiliser manager.