Slurry on grassland

Published 14 March 14

Spreading slurry on grazing ground

Everyone understands the importance of achieving good residuals at the first grazing round and therefore you need to make sure you don’t cause problems by contaminating the area with slurry says independent soil and grassland consultant Chris Duller.

There is enough dead and decaying material at the bottom of the sward after the winter for the cows to contend with already. Don’t discourage them further from cleaning up by adding slurry contamination to the sward.

You’re looking for a clean efficient clearing of the grass to set yourself up for future grazing rounds. If cows are faced with contaminated material at the bottom intakes will suffer and they’ll not make the residuals you need causing problems for the future.

Instead, look at spreading on silage ground, where you’ll have seven or eight weeks before cutting. The issue is that if conditions stay dry slurry can hang around and contaminate the grass. Using a dribble bar or injecting will cause less contamination problems than a splash plate.

Where the ground is still quite wet injectors may smear, there is also the issue of the weight of the machinery on the wet ground.

Some contractors are using soil aerator/slurry spreader combinations in the belief that this will improve slurry infiltration, particularly of thin watery slurries. However in wet conditions the aerator slots may smear causing damage to the  (link to compaction on website)An alternative to spreading in wet conditions on silage ground is to graze some grass off now, when and where you can (link to on/off grazing article) and then spread slurry on the area. It can then be closed up for an early silage cut.

If you’re looking to spread slurry on maize stubble land, give the area a light cultivation beforehand. The heavy rain may have capped the top of the ground and a quick break up will mean you’ll keep the slurry you spread in that field.

Looking at the weather forecast, there seems to be more dry weather ahead, giving a bit more flexibility to your slurry spreading decisions. Unless you’re at the limit of your storage capacity look at holding off spreading slurry onto areas earmarked for the first round of grazing in order to avoid contamination.

 

DairyCo is funding a project at Scotland’s Rural College (SRUC), with Harper Adams University College and the University of Reading, under the Grasslands, Forage and Soils Research Partnership. The study evaluates the degree to which slurry application on grazing swards can influence the grazing habits and performance of late lactation dairy cows.

The project so far looked at grazing behaviour on areas treated with:  

  1. separated slurry
  2. whole (non-separated) slurry
  3. inorganic fertiliser.

Paddocks were grazed 18-24 days after slurry application with dribble bar technology. Initial findings have shown no difference in grazing behaviour across all three treatments or in the amount of rejection area on any of the paddocks. More updates on this study will follow in future issues of Forage for Knowledge.