11 March 2022

The Cultivar Conundrum

FarmWise® Consultant Darren Sutton explores which seeds farmers should be sowing into their paddocks at this time of year.

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This time of year I often get asked about what seed we should be sowing into paddocks after crops and to improve pastures after another tough summer.

Having worked previously for a seed company I know how confusing it can be and the advertising all looks amazing!

Right seed, right place

Depending on the length of time you want a pasture to last for, you will choose a different cultivar based on the longevity and endophyte level.

If you intend to crop that paddock next spring then an annual or Italian Rye will be your best choice. These will produce a lot of feed over 6-9 months then die or go dormant and lose production.

If you think that a paddock will be cropped in 18 months’ time, then moving a to a Hybrid ryegrass will be better. These are basically a crossbred plant of both perennial and Italian ryegrasses. You get better winter production but also some better tiller density and persistence through the following summer. These usually all have an endophyte to help reduce insect pressure.

If you’re planning on returning a crop paddock back into permanent pasture in the Waikato, then your best results are going to be using a dense diploid perennial ryegrass with a strong endophyte.

This is also the best type of seed to use when undersowing into open pastures that need topping up the plant population that has opened up showing lots of gaps.

Summer dry

Endophytes

For any 6-month annual ryegrass you don’t need to spend the money on an endophyte. If you expect to get 12+ months out of a grass, then you will need endophyte in the seed in the Waikato where there is plenty of insect pressure. In the Waikato the two best endophytes I see working are AR37 and NEA4.

Tetraploids

Tetraploids have bigger cells and less structural parts for their cell size. This means that they are more palatable for animals and we see higher animal production. They also have lower tiller density (i.e. lower persistence) when you cannot protect them from drought or over-grazing. If you had a silt loam with irrigation in the Waikato, then you could keep tetraploids on your farm successfully.

Most hybrid ryegrasses are tetraploids and so we can accept them to last for 18-24 months.

Forage Valuation Index

There is now an independent forage valuation index that DairyNZ oversees. They trial, evaluate and rank all the available cultivars in NZ. This shows the regional and climatic differences helping answer the question of what will suit my farm?

As part of the NZFVI, DairyNZ has now released a Cultivar Selector Tool online. This allows you to choose your region and narrow the choices down using what you know works on your farm. This will result in a list of cultivars that have been tested and proven to suit what you need. It also ranks your choices in a confidence level out of 10 based on how many years of testing and numbers of trials it has been through.

You can find this tool on the DairyNZ website.

The Table shown is what was produced when I selected Upper North Island region, late flowering diploid ryegrass with AR37 or NEA4.

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Alternative species

As we see hotter and longer summers, it is natural to look at other species that are better suited than perennial ryegrasses. Some of these alternative species can add or reduce the total MJME grown per hectare per year.

Additions to seed mixes like plantain and chicory can work well. These have better root structures to survive dry summers. They can vary a bit in palatability through the seasons, and they also complicate weed spray programs. To avoid the weed issue, you can broadcast or add to the fertiliser in the following autumn these seeds to introduce them once the spring weed sprays have been done.

Trials have been done on milk production of comparing fescue with ryegrasses. This showed that while Fescue did grow more DM, it did not provide more ME, and milk production was lower.

I still can see the merits of adding in some newer fine-leafed cocksfoot to help with summer production and persistence. This is working well on some farms on light ash soils.

Hopefully we see more research going into these alternate species and how to integrate these on farms to help solve the persistence issues. This is starting to happen now.

So have a look at the cultivar tool to help cut through all the advertising and find what will suit your farm. Also be observant to what has worked in the past for you. It is good to record what paddock has what cultivar to find what suits your farm best.

Darren Sutton, LIC FarmWise® consultant – Waika