Choose the right grasses when reseeding

Published 27 February 15

To ensure a return on investment from reseeding, it is essential to sow the right type of grasses for the site and the job in hand, says Rod Bonshor of Oliver Seeds.

Maximising pasture growth, as long as it is utilised efficiently, is one of the most positive ways to counter volatile milk prices, primarily because it helps to contain bought-in feed costs.

Dairy farmers should set physical expectations for each field or paddock in terms of productivity. In the Grass value study of 12 Welsh farms between 2011 and 2013, the top 10% of the non-organic paddocks grew 15.2t DM/ha of grass a year, while the lowest performing grew less than half, 6.9t DM/ha. Even within a farm, yields can vary dramatically from field to field, depending on sward age, soil conditions and management.

As a ley gets older, production usually falls, as the sown species’ are replaced by invasive weeds and native grasses. Therefore, it is important to prioritise those fields which have more than 50% non-sown species.

Higher energy and yields, plus a better fibre digestibility of younger, modern grass varieties, have prompted many dairy farmers to move to shorter-term leys which can deliver more milk per hectare.

When selecting a new grass mixture, always make sure that varieties included in the mixture appear on the Recommended Grass and Clover List. These have been through many years of breeder trailing, as well as independent testing to make sure they are suited to UK conditions.

There is also a move away from ‘dual-purpose’ leys. Does the paddock need to present animals with an attractive, palatable sward that is easy to bite and chew – or produce high tonnages of young leafy material that will turn into high-quality conserved forage? Different types of grass will be better for one or other of these situations.

Grasses are classified according to heading date – the day when 50% of the ears in fertile tillers have emerged. Early varieties reaching this stage in the first two weeks of May are generally good for making silage. Grasses that head a month later are better for grazing.

There are also diploid and tetraploid varieties. This relates to the number of chromosomes in their cells – tetraploids have twice the number that diploid varieties have. This makes their cells bigger and means they have larger seeds and leaves and they establish quickly. They are particularly useful for overseeding, as they are better able to compete with established grasses.

For silage

Cutting leys should be a mixture of vigorous, upright grasses that exhibit rapid regrowth after defoliation such as Italian and hybrid ryegrasses.

Choose the right grasses for the job in hand

Photo 1 Choose the right grasses for the job in hand.


For grazing

The aim for fields that will mainly be grazed is to maintain a dense sward, especially on difficult land that may have heavy soil, prone to poaching.

Late heading perennial ryegrasses with large leaf area and prostrate growth, are ideal. Look for those that have the greatest resistance to the two main fungal diseases, dreschlera and crown rust, which can decimate swards later in the season.

For more information about reseeding, download chapter 12 ‘Renewing swards’ of Grass+.