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Monday 24 September 2018

Why spring reseeding is an under-rated option

Philip Whitford, Ballyellen reseedeing 12ac with Master Crop Extended for Philip Donoghue, Goresbridge
Philip Whitford, Ballyellen reseedeing 12ac with Master Crop Extended for Philip Donoghue, Goresbridge
Eoin O'Sullivan, Tom Helen and Val Keohane at the tractor run at Ahiohill, West Cork in aid of the local National school. Photo: Denis Boyle
Mary Kingston

Mary Kingston

After the frost and snow it has taken farmers a while to right themselves.

Calving in such conditions would have seen undesirable consequences in every yard, adding to the pressures on silage and slurry storage that were an issue before the storm.

Thankfully conditions have stabilised in the last week and spring management plans recommenced as normal.

Grazing has also resumed with ground conditions drier than expected after the thaw.

I walked the farm to assess the pasture cover and found that, as often happens in Kerry, some grass cover had disappeared on heavy covers without even grazing.

That said, growth over the last month was noticeable on lighter covers.

It's therefore too early to say whether grazing deficits will continue this spring or whether April will come with a bang and see grass growth exceed demand.

We commenced grazing only a week before the snow and with cows housed during 'The Beast from the East', the percentage grazed is on the lower end.

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Available regrowth for the second round is limited which will result in the first rotation being prolonged until mid-April at this stage.

Adjustments

Future adjustments will be made as growth and ground conditions in March and April improve, but the prospects of an early spring seem unlikely.

However, it can be surprising how quickly things can turn around in April.

When grass growth kicks off you need to be ready to close up silage fields and to consider the opportunity to reseed while balancing grass growth and demand.

Where silage reserves are low the first calculation to be made is how much ground needs to be closed-up for first cut silage.

Building up silage stocks after a winter of prolonged demand must be a priority, especially on farms where stock numbers are increasing.

The opportunity to grow more grass per year from reseeding must also be given serious consideration and requires a planned approach.

Most reseeding in Ireland takes place in the autumn, yet spring reseeding offers farmers greater opportunities to establish a well-germinated, weed-free sward.

April is often an ideal month to reseed if circumstances are favourable, but first you must decide which paddocks are best suited for reseeding.

The objective is to reseed poorer performing paddocks with low perennial rye-grass content.

These old pastures often only support four to six grazings per year, whereas a reseeded paddock will achieve in excess of 10, so this can be a good starting point.

Those monitoring pasture covers can also refer to the tonnes grown per annum if using PastureBase or the like.

Ideally, reseeding decisions will be supported with recent (previous autumn) soil test results.

Getting the soil fertility right is crucial if perennial rye-grass is to establish well and persist.

The soil needs a pH of 6.3, but do not apply more than 3t/acre of lime in one single application.

Soils of index 3 will require at least 40kgN/ha, 30kgP/ha and 50kgK/ha at reseeding to aid root development and growth.

Lower indexes will require increased rates for P and K.

Spraying off the paddock will aid weed control but begin cultivation within seven-10 days to minimise turnaround time.

Ensure a low level of trash pre-cultivation, especially if using minimal cultivation techniques.

Regardless of the technique used, ensure a fine and firm seed bed.

In terms of seed mixtures it's essential that you pick a mix that suits its purpose.

Key traits for grass- based dairying are high spring and autumn production, high mid- summer quality and a good ground cover and persistence.

Use a mix of no more than four cultivars, with a minimum of 3kg per cultivar with less than seven days range in heading date.

Use the PBI index to assist in this process and sow at least 14kg of seed per acre.

Rolling

Rolling will ensure seed to soil contact and minimise the pulling of loose plants.

Five to six weeks post-sowing it's essential to use a post-emergence spray so that weeds are caught at the seedling stage.

Post-emergence spray is crucial to achieve a weed free sward and the best money you'll spend in the whole process.

Finally, take the first grazing at no more than 1000-1200kgDM/ha and do not close this sward for silage.

After that, graze at 1200-1400kgDM/ha and whatever you do, do not poach.

Mary Kinston is a discussion group facilitator and consultant, and farms with her husband in Co Kerry

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