Organic fertiliser acidification technology can reduce the amount of ammonia emitted by organic fertilisers and increase the amount of nitrogen available to the crop.

That is according to Vogelsang, which is bringing the Danish-developed SyreN system, an on-board sulphuric acid dosing system that treats slurry or digestate as it is applied to the crop, to the UK market.

Using the system, up to 70% of harmful ammonia emissions can be converted to nutrient-rich ammonium, says the company.

Vogelsangs SyreN specialist Sion Williams says: The UK and the EU have set out plans to reduce agricultural emissions by 2030.

Treating slurry with acid delivers this and has the added benefits of increasing yield, reducing input costs and reducing the prevalence of odours which occur during application.

The acid is carried in a frontlinkage-mounted unit and is dosed when the organic fertiliser is fed to the applicator, with a pH regulator automatically controlling and adjusting the flow.

It is also possible to add a side tank for additives, such as a nitrification inhibitor and a further water tank to flush the system.

The entire system can be retrofitted to almost any dribble bar, trailing shoe, or injection applicator and span widths up to 36 metres, says Vogelsang.

Uptake The nitrogen uptake from organic fertiliser is additionally increased because the acid causes it to expand by about a third when it converts the ammonia to ammonium; the organic fertiliser is therefore more easily absorbed by the soil and more nutrients reach the crop, it is claimed.

Results from a German study carried out over three years by the Chamber of Agriculture for Lower Saxony showed that acidifying digestate applied via a dribble bar or trailing shoe led to a 6-12% increase in wheat yield.

This is due to the higher ammonium concentration and improved phosphate bioavailability.

In addition, the sulphur contained in the acid also becomes available to the plants as sulphate after spreading.

This also has the benefit of eliminating the need for an additional pass over the field to administer a supplementary sulphur fertiliser, such as ammonium sulphate nitrate, adds Mr Williams.

Costing in the region of £85,000, as mild acidification equipment for slurry the system is eligible for up to 40% funding under Defras Farming Transformation Fund Improving Farm Productivity Grant, says Mr Williams.