New treatments cut N losses from slurry by 97pc

NITROGEN losses from slurry during storage were reduced by 97pc through treatment with ferric chloride, in trials carried out at Teagasc Johnstown Castle.

Researcher Ian Kavanagh presented an update on the study which is looking at the impact of the addition of a variety of biological and chemical treatments or “amendments” to slurry during storage.

The next most promising amendment was alum, the addition of which reduced N loss by over 80pc compared to untreated slurry.

Lesser improvements were achieved with (in order) sulphuric acid, acetic acid, sugar beet molasses and dairy waste.

The amendments also had the effect of reduc- ing methane emission and reducing crusting, which would suggest a potential reduction in slurry agitation costs.

However, the Teagasc researcher warned that these amendments are not cheap and thus the financial cost-benefit of each needs to be evaluated.

A pilot-scale study is planned for winter 2019 to further investigate the effects of the various slurry amendments on gaseous emissions to air, plant availability of slurry nutrients and grass growth response post-slurry application.

In particular, they will be examining whether ferric chloride and alum have an effect on phosphorous availability.