Addressing persistence issues

Addressing persistence issues

Lack of persistence in ryegrass pastures has long been a bone of contention among dryland sheep farmers but ten southern farmers are seeking to address the issue.

The farmers from Southland and Otago are part of Agriseeds’ Rohan Challenge and will be using the company’s recently released Rohan spreading ryegrass in conjunction with pasture establishment and management practices to try and improve the persistence of ryegrass pastures.

Graham Kerr, a pasture systems manager with Agriseeds, said while Rohan has been bred to improve persistence nothing was a silver bullet.

“What we need to do is get it managed in the right way and we will get some great gains in persistence on farms.”

Kerr said his company will be working alongside these farmers for at least five years and would be rolling the programme out to other parts of the country where pasture persistence was an issue. He added improving pasture persistence in the sheep industry was not a short-term issue.

“It’s about matching good plant genetics with the appropriate stocking policies and management and using that package to good effect.”

Kerr said often it was about getting factors like soil fertility and spring management right in order to set up a strong, healthy plant that can cope with dry summers.

He said there were two parts to the Rohan Challenge. First is to work with farmers to improve the performance and persistence of Rohan pastures on their farms. The second is to help sheep farmers across the industry better manage ryegrass pastures to achieve greater persistence.

The ten farmers involved in the southern part of the Rohan Challenge come from a range of hill-country environments, each with its own set of difficulties. These include altitude, summer dry, summer wet, weeds, soil fertility, porina and short growing seasons. At a day held to discuss their farming businesses and expectations of pasture, all the farmers said that four to five years was as long as they expected young grasses to perform at better than average. All had a pasture renewal cycle that revolved around the area required for winter crops so this ranged from seven to 20 years. Only one farmer used grass to grass renewal – this was in paddocks that weren’t suitable for cropping.

David Stevens from AgResearch reminded farmers they needed to be sowing ryegrass pastures when soil temperatures were 10C and rising.

Increased row spacing allowed more room for weeds so decreased spacing, cross-drilling and broadcasting all ensured improved ground coverage and gave seedlings a better chance by decreasing intra-row competition.

‘If you can see better strike in the tyre lines from the tractor then the paddock wasn’t consolidated enough.’

The optimal depth for ryegrass seed is 2cm – 1cm for clover. Clover can be sown at a later date or spun on with fertiliser.

Stevens said ryegrass was very competitive in its first year because it took advantage of higher soil fertility from the previous crop and the fertiliser applied at drilling.

In the second year, even with maintenance fertiliser, soil quality decreases again, the ryegrass is not so vigorous and the clover was more competitive. 

Seed bed consolidation was important after drilling.

“If you can see better strike in the tyre lines from the tractor then the paddock wasn’t consolidated enough.”

Once passing the pull-test, pastures could be given a nip-off graze. It was best to do this using a large mob, preferably ewes, for a short time in dry conditions. This promoted tillering and allowed light in for the clover to thrive, Stevens said.

The object of this first graze was to remove the top third of the plant and leave 1500kg drymatter (DM)/ha. Applying 25 units of nitrogen after the nip-off graze would help the ryegrass because it increased tillering.

Weed control and best management practices are also important in that first season. This meant grazing at the 2.5-3 leaf stage leaving 1200-1500kg DM/ha, rotational grazing rather than set stocking and stocking at an appropriate rate.

Weed spray

Few of the participating southern hill-country farmers in the Rohan Challenge used weed spray because they questioned the cost of spraying compared to the value. However, all recognised that future pasture persistence could be affected by weed competition at sowing.

Half the group set stock new pastures at lambing in expectation of higher drymatter production and continued to use these paddocks for hogget lambing. This practice also has the potential to affect persistence into the future.