Farmers looking for a good-yielding, high-quality silage crop will be targeting a cutting date of between 20 and 30 May. In those 10 days, target yields are expected to be between 6-7t DM/ha while DMD should also be high at 73-76% because crops should not yet have headed out.

The drop in quality in silage cut after these dates can be significant, with the potential for DMD% to fall three percentage points per week. Being two weeks late cutting could see quality (DMD) drop from 73% to 67%.

Two management factors that will have a significant bearing on cutting date are the closing date and the nutrient requirements of the crop.

Closing date

Depending on growing conditions, a first cut silage crop will take between six and seven weeks to grow. Ideally, it should be closed seven weeks before the expected cutting date, which will give a week to spread slurry and fertiliser.

With a target cutting date of 25 May, for example, ground should be closed around 5 April.

Obviously, best practice is to have all silage ground grazed off prior to closing to eliminate that dead butt of grass which will drag down the silage quality.

However, on many farms, because of the wet start to March, grazing planners are running behind and time is running out to get silage ground grazed.

My advice here would be to stick to the closing off date, grazed or not grazed. If you delay your closing date by a week, cutting date be pushed back into June and even the second cut is going to be significantly affected.

Graze what you can and stop when you reach the closing date. If some ground is left ungrazed, it can either be cut in early May at a reasonable quality or left with the rest of the first cut but at reduced quality. It will still be adequate feeding for dry cows tough.

Nutrient requirements

Failure to get nutrients right is often the number one cause of poor silage quality. If the right nutrient balance isn’t allocated to the crop, farmers can often get caught waiting for a crop to bulk-up and the expense of silage quality. Crop nutrition should be planned carefully to ensure the yield is on target at the right time.

Table 1 details the N, P and K requirements to grow a first-cut silage crop depending on soil index.

With that, farmers can then work out a fertiliser/slury plan based on the needs of the crop. It is important to remember that every 1,000g of cattle slurry contains 7 units of N, 5 units of P and 30 units of K.

Finally, where conditions allow, urea can be used as a replacement for CAN. Cool conditions and at least 10mm of rain will be required to avoid N losses from urea.