Fertiliser

A lot of silage has been made in the last week and more will be made in the coming week, weather permitting. Thoughts will be turning to fertiliser for second-cut silage and grazing. The old advice was to spread 80 units/acre of nitrogen for second-cut silage, but it’s likely that you can get away with less. Spreading 70 units instead of 80 units will reduce annual fertiliser use by 5% on farms spreading 250kgN/ha. It’s a small difference but it all adds up.

Spread the equivalent of two bags/acre of 0:7:30 or 2,500 gallons/acre of slurry to provide the phosphorus and potassium requirements for second cut. Every 1,000 gallons/acre of slurry spread in summer is worth the equivalent of one bag/acre of 3:5:20 or 6:5:20 if the slurry is spread with low-emission technology. Deduct what nitrogen is supplied in the slurry from the amount of chemical nitrogen required. It’s a good opportunity to spread lime on fields with low pH. Spread the slurry and fertiliser first and go with lime a week or so later. If no second cut is planned, 20 to 25 units/acre of nitrogen should be sufficient. Don’t forget to top up fields with potash if the full requirement wasn’t applied when closing for silage. Some farmers stagger the potash application pre- and post-cutting to reduce the risk of milk fever from high-potash silage.

Grazing

Residuals were generally brilliant in April but very poor in May due to the wet conditions. Maintaining quality grass and high milk yields will be a challenge in June. On pages 32 and 33 we report from a farmer in Cork who plans to skip over stemmy paddocks and do a good bit of pre-mowing over the coming weeks.

The thing to remember with pre-mowing is that it reduces the cow’s ability to select the nice grass, effectively forcing her to eat the stemmy stuff. For those who are lowly stocked, allowing residuals to creep up and letting cows select the nice grass and leave the stemmy grass will probably be a better policy. Although the swards will look dirty, the actual quality of the grass the cows will be eating will be much higher than forcing them to eat pre-mowed grass.

For those who are higher-stocked, pre-mowing can be a useful tool, but if the paddock is too strong to graze, pre-mowing is not the answer – put it in a bale. Cutting, pre-mowing or topping will reduce the growth rate on the paddock. So if a lot of the farm is being cut, be prepared for a reduction in average growth rate.

Non-return rates

It’s early days but I’m hearing of lower than normal non-return rates. This is the percentage of cows that don’t repeat within 24 days of service. You would expect to see non-return rates of between 60% and 70% but some herds are at around 50% at the moment. It’s still early days as most farms are only four or five weeks into breeding. Bad weather in May could be a reason for the lower than normal conception rates. Work out the figures for your own farm. Are certain bulls repeating more than others? Is body condition score an issue? Is heat detection accurate? Are the cows being inseminated correctly?