31 March 2000

Cutting dates crucial for high quality silage

WHEN trying to make high quality grass silage the most important factor is getting the cutting date right.

According to Tim Keady of the Agricultural Research Institute of Northern Ireland, this date is relative to grass maturity, but it is more important than the amount of nitrogen applied.

In his study at Hillsborough, Co Down, silages were cut on five dates from May 10 to June 6, with five different nitrogen application rates at 79-166kg/ha of nitrogen (63-133 units/acre).

"The level of nitrogen applied had no effect on silage digestibility in the rumen, but harvest date was important in fibre degradability. But nitrogen fertiliser should be taken into account to avoid poor fermentation and for the most economic response," he added.

In the study, ammonia N contents in silage were acceptable between 4% and 14%, but in a poorer growing season these may have been higher.

He advised using a maximum of 125kg/ha (100 units/acre) for an early cutting date and 144kg/ha (115 units/acre) for a late May cut under optimum management.

"Get the date right, then the nitrogen, then use an additive: An inoculant additive performs well under a wide range of conditions," said Dr Keady. &#42