Most people would agree that topping is a fairly good indication as to how good or bad grassland management is on a farm.

Frequent topping during the course of the grazing season in an effort to bring grass back under control points to a number of issues including stocking rate, pre-grazing grass height (covers) and grazing infrastructure, for example.

That said, it still does have a role to play.

Benefits

From a grass quality point of view, it has benefits. Grassland research in New Zealand showed that topping pasture after grazing increased the quality of pasture by 0.6 MJ ME/kg DM (metabolisable energy/kg DM) during spring and summer. It also showed that topping resulted in a higher DM intake (1.9kg DM) during midsummer.

The same research, however, did go on to show that overall grass DM production for the year decreased as a result of topping and concluded that the practice should be very much a quality control measure in isolated cases rather than a whole-farm approach to grassland management.

The current situation

At this stage, most grazing blocks will be on their third rotation and some may be on their fourth or even fifth. After a number of grazings, it is highly likely that a thicker butt will be starting to appear in many swards, and the graze-outs that were being achieved a month ago will be a lot harder to achieve this time around.

Added to this, growth has been excellent over the last two weeks. Grass that was moving steadily at 8-9cm was suddenly over 10cm and 12cm.

The general rule of thumb is to remove any strong grass covers as surplus silage and this should still be the first port-of-call – but this needs to be within reason.

Bales

Putting a large area of ground into bales and falling into a situation where you have too little grass is not the right thing either.

At this time of the year, you need 10 days ahead at minimum, and 12 to 14 to be comfortable. Anything over this, by all means cut away.

But with many facing the need to graze a small number of heavier paddocks to keep grass in front of cattle, there is every likelihood that post-grazing covers will be higher than what they should be, particularly on wet ground.

For these reasons, topping should at least be a consideration during the next rotation.

Things to consider

Here are just a few points to consider.

  • First-things-first, topping should be kept to the absolute minimum. It should not be done for aesthetics and only to serve the purpose of cleaning a sward. After all, it costs time and money.
  • Topping should only be carried out on grass from 5-7cm in height. Grass below this height after grazing shouldn’t need to be topped. Grass above this height after grazing signifies a much bigger problem in terms of grass and grazing management.
  • Topping will slow down regrowths. The blades of the machine will damage the grass plant unlike the biting action of the cow. It should be noted that the more grass you have to remove, the greater the slower grass recovery will be.
  • Top to a height of 4.5cm (certainly under 5cm). You want to be cutting the tall grass from sour dung pats, but avoiding the small regrowth.
  • The worst machine is an ordinary topper. It won't take the cutting height down to 5cm. A disc mower is ideal. Sharp blades will do less damage to the grass plant.