Anyone that’s not watching grass growth will be in for a shock because, as one farmer described it over the weekend, growth is “through the roof” at present.

The fine weather over the weekend saw mowers, rakes and balers emerge from winter hibernation.

Some farmers that didn’t graze in spring took the opportunity to cut the first cut, but the majority of farmers that did silage over the weekend did so to remove surplus grass.

Unlike grazing, removing grass in the form of baled silage returns nothing to the land. One of the main reasons many grazing fields are becoming deficient in potash is because the nutrients removed when taking surplus grass as baled silage is not being replaced.

For every 2,000kg/ha of grass removed as bales, 5kg more phosphorus and 50kg more potash are removed than if the field was grazed.

These nutrients can be returned by spreading 1,400 gallons/acre of thick slurry, or 3,000 gallons/acre of watery slurry.

With grass growth rates so high, the question is whether should farmers close up surplus paddocks and add them to the first cut silage or should they cut them as soon as possible.

The answer to this depends on the demand for grass and where one expects grass growth to be over the next few weeks.

An ideal demand is somewhere around 65kg to 75kg per hectare per day. If by closing up strong paddocks for long term silage the demand is pushed up to 80kg/ha/day or higher, I would be inclined to cut sooner rather than later.

This is because it is unlikely that grass growth rates will remain higher than 80kg/day for the next few weeks, so there is a risk of a grass deficit if demand is greater than growth.

Continue to keep on top of grass by measuring every five or six days and making sure that cows only go into the correct covers of 1,400 to 1,600kg. Achieving a good clean out is critical for grass quality and cheap milk in the next rotation.