Take steps to improve soil fertility

Soil fertility is the biggest reason for reseeding failures. That was one of the key messages that farmers got from the Teagasc/Aurivo farm walk in Roscommon with last week. Enda Faulkner from Aurivo Co-op told farmers at the event that the number one improvement that could be made on farms in the west related to soil fertility.

“People think reseeding is the most important but really soil fertility should be first on the list,” Enda said.

The pH of the soil needs to be above 6.3 along with index 3 status for phosphorus and potassium. This adds cost to fertiliser application but nitrogen will be more efficient when soil indices are at the correct level.

Grass varieties

Mary McEvoy from Germinal Seeds told the farmers present that the pasture profit index should be the first port of call when selecting seed varieties.

The varieties on this list have been tested under Irish conditions for the last four years, so farmers can choose from this list with confidence that the varieties at the top will perform under Irish conditions.

When putting a mix together, 60% diploid and 40% tetraploid is a good choice. Tetraploids will bring good growth characteristics, an upright growth and larger leaves which will be more palatable.

On the inclusion of clover, Mary recommended a 0.5kg to 2kg inclusion rate for reseeds depending on preference and grazing management

Diploids will add density to the sward and act like a thick carpet under animals, which will help grazing more difficult land types or early in spring.

On the inclusion of clover, Mary recommended a 0.5kg to 2kg inclusion rate for reseeds depending on preference and grazing management.

Grass will start to grow at 60C, while it needs to get to 80C until clover starts to grow. If weeds are a big issue you may be better to leave out clover at reseeding, use a post-emergence spray and then oversow the clover at a later date.

Weed control in new reseed

Chris Maughan from TP Whelehan Crop Health gave a presentation on weed control in new and existing leys. Docks are the biggest problem weed to control and the biggest issue is spraying them at the right stage.

Once grass is at the two- to three-leaf stage, spraying should take place if weeds are present. Killing a seeding dock is a lot easier than killing a dock with a large tap root, so reseeding is a perfect time to correct an issue.

A 10% dock infestation can reduce grass yields by 10% per hectare. Chris recommended a six-week post-emergence spray to control weeds in a new reseed.

For established grassland, timing is also critical and spraying docks with stem is pointless.

Using a spray such as Pastor Trio at half rate can work well if the other half is applied within 12 months. Autumn is a good time to spray as the weed is naturally pulling nutrients back down to the root.

Post-reseeding management

Seamus Nolan, Teagasc adviser in Roscommon, highlighted the importance of post-reseeding management in a successful reseeding programme.

“Some people think that the P and K stops at reseeding, but it does not work like that. New grass varieties are bred to grow in high fertility conditions so nitrogen, phosphorus and potassium are all very important in the first few years.”

Grazing management is also equally as important in the first year. Grazing at low covers is key and avoiding a silage cut in the first year is a must.

The first grazing should take place at a very low cover of about 700kg to 1,000kg (7cm to 8cm) and a grazing should take place every 17 to 21 days after this to promote good tillering and thickening of the sward.

An Erth agriseeder was on display and the McHughs have achieved good results using this machine

On reseeding methods, Seamus said that once whatever method used was done correctly, there was not a lot of difference between methods.

An Erth agriseeder was on display and the McHughs have achieved good results using this machine.

Granlime goes out at two bags/acre (100kg/acre) at reseeding time. This is important to correct any acidity from surface trash dying off.

Seamus also explained that timing is important in terms of getting a good take.

“You need to have a paddock sprayed off with glyphosate for three to four weeks to get good kill. The first week of September is the last week I would like to be going in so that means spraying this week at the latest.

90% of Irish soils are sub-optimal for either pH, phosphorus or potassium and this has a major limitation on grass growth

– Enda Faulkner, Aurivo Co-op.

Every grass variety on the pasture profit index has a minimum of four years production data tested under Irish conditions so it makes sense to use this list when choosing varieties for your farm

– Mary McEvoy, Germinal Seeds.

Most grass varieties should last 10 years but if soil fertility is not right, they won’t last three years, never mind 10 years

– Mary McEvoy, Germinal Seeds.

In terms of variety choice, a 60% diploid and 40% tetraploid mix is a good split to go with in my experience. It’s a nice balance of ground cover, quality and growth characteristics

– Mary McEvoy, Germinal Seeds.

One dock plant can produce up to 60,000 seeds and last 60 to 80 years in the soil so it’s quite a difficult weed to eradicate

– Chris Maughan, TP Whelehan Crop Health.

Spraying docks with stem or diseased leaves is pointless. You need to be hitting them at the rosette stage when they have a lush green leaf

– Chris Maughan, TP Whelehan Crop Health.

On drystock farms, in particular, we need to make sure new reseeds are fed adequately in the first two to three years. I have seen many reseeds fail because of low nitrogen applications

– Seamus Nolan, Teagasc adviser, Roscommon.