Trailing shoe reduces N bills on grazing

Trailing shoe reduces N bills on grazing

Tuesday, August 9, 2011

Applying slurry to dairy cow grazing ground in summer using a trailing shoe applicator can replace up to 150kg N/ha, according to trials at AFBI, Hillsborough, funded by AgriSearch.

Dr Andrew Dale and colleagues found no effect on cow grazing behaviour or milk production in studies replacing 80kg of bagged N/ha with two applications of slurry (31 and 19m3/ha).

A second study replaced 150kg/ha of bagged N with four slurry applications (40, 27, 28 and 19m3/ha), at two grazing intensities. This found that at normal intensity grazing to a 6cm residual there was no effect on cow performance, but with tight grazing to 5cm there was a 1kg/cow reduction in milk yield.

Andrew concludes that clearly under normal grazing management slurry could be applied to replace up to 150kg N/ha, saving £44/ha in fertiliser (based on CAN at £240/t).

However, care is needed to avoid oversupply of phosphate to the grazing area, he warns.  

The full results of the AgriSearch (the NI Agricultural Research and Development Council) funded study are available online in a booklet 'The Effect of Applying Slurry During the Grazing Season on Dairy Cow Performance' at



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