Although the winter housing period is still ongoing for the majority of livestock farmers in NI, thoughts should now be turning to harvesting silage in 2018.

With cattle housed since late summer, silage stocks are depleted across the country with many farmers having to purchase additional fodder to stretch winter feed.

Grass growth has been limited due to low air and soil temperatures, which has slowed turn-out of cattle to grass.

However, with temperatures on the rise, it is crucial that fertiliser is applied to grazing ground as early as possible to kickstart grass growth.

Silage fertiliser should also be applied over the coming week to maximise yields during the period of peak grass growth in May.

Options

When it comes to silage options for the year ahead, many farmers will be thinking of cutting silage later than normal to build up silage reserves.

While this is understandable, delaying the cutting date of first-cut silage can have a negative effect on second-cut yield.

Instead, it may be more practical to target cutting silage as close to the normal harvesting date as possible.

The aim should then be to harvest a second cut in late July or early August and, if possible, a smaller third cut of silage in September.

The following are a series of steps outlining the options for maximising silage yields over the year ahead.

1 Apply fertiliser now: applying fertiliser before the end of April will allow you to harvest silage in early to mid-June. Target 80 to 100 units of nitrogen per acre from chemical fertiliser.

If ground conditions are borderline for carrying slurry equipment, apply the chemical fertiliser now. Slurry can then be applied a week later when ground conditions improve. Ideally, fertiliser and slurry should be applied a number of days apart.

As many silage fields in NI are deficient in phosphate (P) and especially potash (K), using a compound NPK fertiliser such as 24-6-12 is often required to increase yields. Under the Nitrates Action Programme, P can only be applied after a soil analysis has shown there is a crop need.

Compound fertilisers are more expensive than straight CAN products, but the extra yield that can be achieved when applied to nutrient deficient soils makes them cost-effective.

For example, applying three bags/acre of CAN (£220/t) will have a fertiliser cost of £33/acre. Assuming a yield of 10t/acre, the fertiliser costs £3.30/t of silage.

However, applying three bags/acre of 24-6-12 (£280/t) has a fertiliser cost of £42/acre. Assuming the application of P and K has increased yield to 12t/acre, then the fertiliser costs £3.50/t of silage.

Finally, sulphur deficiency is now widespread, and most prevalent in the spring. Sulphur containing fertiliser should be applied to all first-cut silage swards.

2 Do not delay cutting date: silage should be harvested once grass begins to produce seed heads and the base of the sward is starting to die back and turn white.

At this point, there is no benefit in leaving the sward for another week to 10 days to increase yield as the plant has already reached maturity.

If harvested at this stage, silage can still have a good feed value, which is also important to reduce the level of concentrate feed required during the winter housing period.

Wilting grass for a 24-hour period after mowing will increase dry matter, and reduce the risk of any residual nitrogen in the sward.

Delaying cutting date beyond the date that the plant has reached maturity will slow regrowth and affect the yield of second cut.

As grass growth naturally declines for a brief period in early July, the knock-on effect will be a lower yield of second cut of silage if harvesting during August.

3 Fertilise straight after first cut: to maximise the yield of second cut, it is important to harvest first cut on time and to get fertiliser applied straight after.

Applying 70 to 80 units per acre of a compound fertiliser is recommended to replace the nutrient offtake from the higher yielding first cut.

Applying chemical fertiliser first means you can still allow cattle to graze the headlands of silage fields for a short period. Remove cattle after one week and apply slurry straight after.

4 Target second cut for early August: if first cut has been harvested by mid-June, target a harvesting date of early August for second-cut silage.

As grass does not produce seed heads in August, there is an opportunity to make high-quality, second-cut silage and still maximise yields.

As with the first cut, you should move to harvest the silage once the base sward is turning white.

5 Take a small third cut: second cut will naturally be lower yielding than silage harvested in June. Therefore, if you can harvest your second cut on time, there is an option to take a smaller third cut in September after a short five- to six-week period of regrowth.

Apply 50 to 60 units/acre of fertiliser straight after second cut. Third cut can be baled if there is insufficient storage capacity in silage clamps.

Mark bales with paint so that they can be targeted to specific stock groups based on feed quality.

6 Harvest surplus grass on grazing ground: an alternative option to increasing silage yields this year is to harvest surplus grass from the grazing area.

By applying higher rates of fertiliser on grazing ground, there is an opportunity to make additional silage either by baling surplus grass, or closing off paddocks and harvesting along with first cut.

This will reduce grazing demand and allow more land to be closed for silage, thereby increasing fodder reserves for next winter.

7 Reduce stocking rates: where farmers have reduced their stocking rates by selling more cattle than normal this winter, it may be beneficial to maintain the lower stocking rate this year.

This will reduce grazing demand and allow more land be closed for silage, thereby increasing fodder reserves for next winter.

Alternatively, autumn cows should be weaned before turn-out and stocked tightly as they have a lower grazing demand.

Early scanning of spring calving cows in September will identify barren cows that can then be sold before the housing period starts. Cows can be accurately scanned from 40 days after the end of the breeding season.

8 Whole-crop silage: for farmers working on better quality land that was heavily poached in 2017, there may be an option to reseed swards by under-sowing a field of spring barley.

The barley can then be harvested as whole-crop silage with the reseeded sward then grazed by lighter stock in late summer and autumn.

The whole-crop option can be more expensive, but it will increase the tonnage of silage grown this year.

9 Cut headlands of cereals as whole crop: an alternative to under-sowing barley with grass seed is to cut the headlands of winter and spring cereals for whole-crop silage.

The headlands and perimeter swards tend to be lower-yielding areas, therefore, cutting them for silage will boost fodder reserves.

10 Forage rape: farmers working on drier land should consider the merits of growing a small area of forage rape.

This could extend grazing into late autumn for lighter weanling cattle, or dry cows should ground conditions permit, thereby reducing silage demand in winter.

Choose a drier field with plenty of shelter and sow out in late June to early July. Leave the field headland in grass to serve as a lie-back area.