The good weather at the end of last week and into the weekend resulted in a lot of farmers making a move on harvesting their first cut of silage.

Although cutting this early often results in a poorer yield, it appears that the crops that have been harvest were not as light as many might of thought.

This was helped greatly by the improved growth rates that farms have experienced in the last number of weeks.

Slurry after silage

After silage has been harvested it important that the nutrients that have been taken off by the crop are replenished.

A typical bale of silage weighing 800kg contains about 10 units of nitrogen (N), 1.6 units of phosphorus (P) and 10 units of potash (K).

So on a farm where seven bales/ac were harvested, you’re looking at an offtake of 70 units of N, 11.2 units of P and 70 units of K.

The N that is taken off is replaced by the chemical fertiliser that is spread before and after harvesting, but the P and K generally is not.

Replenishing these nutrients is important, because the removal of 70 units of K can actually turn and index-three soil to an index two.

To take an example, a typical 1,000 gallons of dairy-farm slurry contains six units of N, three units of P and 21 units of K. Therefore, to replace the nutrients removed by slurry, replenishment would need to be applied at a rate of 3,500 gallons/ac, which should be 21 units of N, 10.5 units of P and 73.5 units of K.


The early part of this week has seen the weather take a turn, so farmers should check the weather forecast before they go spreading

Slurry should not be applied when heavy rainfall is forecast.

Spreading slurry when heavy rain is forecast can result in run-off which may lead to slurry entering water courses and impacting on water quality.