Friday, 5 July 2019
The evidence of spring grazing mistakes was revealed from mid-May when grass produced its seedheads. Where cows went into too-high covers, or poached paddocks, the resulting poor residuals will have led to more rejection sites.
It’s a struggle to keep plants in their vegetative state of growth on these rejected areas, particularly if June’s early dry period forced grass into reproductive mode, says LIC grazing consultant Piers Badnell. He has seen more rejection sites this year on farms that have had an extremely dry spring: “Worms and other soil biology went deep and there wasn’t the biological activity to breakdown dung. Also there was more rejection where cows were allocated too much, as dry matters were higher than plate meters recorded,” he explains.
Because it’s hard to keep this grass leafy, now is the time to manage it mechanically and reset the plant for the rest of the grazing season. “Correcting grazing mistakes is basically a need to correct residuals, which stimulates fresh regrowth. If you don’t, these reject sites just get rank as the season goes on.”
Piers reminds grazing managers that the aim is to reset residuals to 1,500 kgDM/ha, or 4 cm. This stubble height is where the grass stores its sugars ready to fuel the first new leaf. It photosynthesises and generates the second new leaf, with both leaves together capturing sunlight to produce the third, final leaf.
“Ideally, where grass varieties have close heading dates, graze paddocks 5-6 days before heading at 2 to 2.5 leaves, when the seedhead is still leafy and digestible. Another option (with the right cow type) is to come back into poor paddocks earlier at 2,500 kgDM/ha and get cows to eat it right down. But for most grazing managers, the practical answer is mechanical,” he says.
The cost-effective options are pre-mowing, or baling. Where recent rain has created a surplus, it’s best to bale paddocks, otherwise pre-mow swards (without a conditioner), so that grass is utilised by cows. Post-mowing simply leaves cut grass to rot which suppresses regrowth and ultimately costs money without getting a return, says Piers.
He also cautions that mechanical correction once a season is a maximum and not every paddock should need it. “Cosmetic mowing after every round is usually the result of too many mistakes and costs money in terms of labour, diesel, and machinery wear and tear, let alone the lost potential of the grass. It’s important to have a plan to identify what went wrong in the first place, to make sure you don’t repeat those mistakes next year.”