In New Zealand’s soils, phosphorus does a great job at growing plants but unfortunately it does the same thing if it makes it into our water.
DairyNZ's regional teams manager, Craig McBeth, says farmers from around the country have been contacting the industry body's specialists and local consulting teams for advice on how to deal with the issue.
"Maintaining high quality pasture while feeding cows during a feed surplus is one of the most important skills of pasture management. This season, which has been milder than usual, is proving a bit of a challenge because there's just too much long grass in many places. Grass being offered to cows is near the top of a Red Band gumboot in a number of areas including the Waikato, Taranaki, Manawatu and Canterbury."
It's important to identify a developing pasture surplus early, create a plan and follow it to hit target grazing residuals, says McBeth.
"If you don't get it right, pasture can deteriorate resulting in lower pasture quality at a time when milking cows need the best quality pasture you can give them to maximise milk production."
Options for farmers include speeding up the rotation, using less supplement and nitrogen, and closing up surplus grass for making silage.
"All of these are valid options but carry some risk and need to be managed," says McBeth. "If pastures are more than 3200kg dry matter/hectare, the milking cows are going to struggle to get through it. This pasture can be allocated to the remaining dry cows, or leave these paddocks out of the rotation altogether. It is better to keep 90% of the farm in good order rather than see the whole farm become affected.
"Rotation lengths can be faster than normal but faster than 40 days is risky for this time of year, as temperatures are still limiting new leaf emergence.
"Grass, and therefore silage quality, changes very slowly at this time of year so the grass can wait until the weather is suitable before you mow. In preparation for this, silage inoculants should be considered," says McBeth.
For more information on managing surplus pasture visit dairynz.co.nz/surplus.