Choosing sowing rates for
Perennial ryegrass pastures
5 September 2018
From time to time, there is some debate in the sector on the ‘correct’ perennial ryegrass seed sowing rate for New Zealand farms. However, as DairyNZ feed developer Sally Peel explains, there’s no one right answer.
Research shows a wide range of sowing rates can result in satisfactory pasture establishment. Seed is also sown under a wide range of soil conditions, so there isn’t one sowing rate to fit all circumstances. A standard recommendation can’t cover all of these but, based on the research, DairyNZ recommends 18 to 20 kilograms of seed per hectare (kg seed/ha) for diploid cultivars, and 25 to 28kg seed/ha for tetraploid cultivars. In some of the circumstances outlined below, a lower sowing rate will be enough.
To read about recent research supporting these standard sowing rates, check out the back page article of this month’s Technical Series magazine. The research also identified that a wide range of sowing rates had little impact on ryegrass productivity, except in the early stages after sowing.
Standard vs lower sowing rates
The table below compares the advantages of standard versus low perennial ryegrass sowing rates.
|Standard sowing rate
(diploid 18-20kg/ha; tetraploid 25-28kg/ha)*
|Lower sowing rate
(diploid 12-16kg/ha; tetraploid 20-24 kg/ha)*
|• Extra seed can help in adverse conditions (e.g. poor seed bed, poor drilling depth).
• Usually higher dry matter (DM) yield over first 1-3 grazings.
• Lower weed content.
|• More space for clover establishment.
• Lower seed cost.
* Regardless of ryegrass ploidy and sowing rate choice, clover seed is typically added at three to four kilograms per hectare.
Good conditions a must for low sowing rate
An advantage of lower ryegrass sowing rates is higher clover content in the pasture, which in turn improves feed quality and animal performance. However, if low ryegrass sowing rates are to be successful, you must have excellent conditions for the new pasture to establish. This includes producing a good seedbed (fine, firm, consolidated). As well as conserving moisture, this allows seed to be sown at the right depth.
Lower ryegrass sowing rates also generally mean more weeds in pasture. If weeds are a problem (particularly grass weeds such as brown top, poa etc.), DairyNZ recommends using standard sowing rates and taking into account the sowing method.
Standard sowing rate increases yield
Using a standard or higher ryegrass sowing rate usually gives a temporary (not long-term) increase in dry matter (DM) yield over the first one to three grazings. This varies, but might be an extra 500kg DM/ha, with a value of $150 to $200/ha (using 30 to 40 cents/kg DM for this high-quality late autumn/winter feed). The cost of an extra six kg/ha of seed may be $60 to $90/ha.
Sowing method affects the speed that ground cover is established, as the diagram below shows. Where weeds are a problem, DairyNZ recommends Method 1.
Method 1: Spreading seed more evenly
- Better ground cover (better weed control).
- More space between plants so better clover
- These methods suit higher sowing
Method 2: Packing seed in wide rows
- Seed packed more tightly in
- Space between rows for weeds
(or clover if it’s sown separately, e.g. small seed box).
- Suits lower sowing
DairyNZ feed developer Sally Peel
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