What is Undersowing?

The practice of undersowing, where seed is either drilled or broadcast into failing pastures (without sprayout), is a common practice on many farms.

Pastures with low numbers of ryegrass plants will produce little feed over the all-important winter period. Drilling with the right seed to boost sward density can be a cost-effective way of maintaining pasture production over these periods while also improving pasture quality.

In an undersowing situation shorter term products such as annuals, Italians and hybrids have more of a fit than perennials as they are quicker to establish and more winter/spring active, making them more competitive for establishment in existing pasture growth rates.

Key Considerations

Some of the key considerations when undersowing are as follows:

Condition Score Pastures

Assess which species will be the best fit for the situation. Having a large area in short term products such as annuals costs more down the line when they need addressing again.

Also feed imported over the summer when the annuals run out is expensive as they also have no endophyte, making them a significant host for insect pests, so care needs to be taken when planning.

Timing is Crucial

The longer drilling is delayed, the slower the species will be to establish and therefore reduce winter yield
Also, the later you start, the more opportunity there is for weeds to fill in the open space, which will limit the result of undersowing

Weeds

Check the presence of broadleaf weeds and weed grasses and decide on the best course of action to remove these if required.

Slug Bait and Cricket Bait

If direct drilling or oversowing, slug bait and/or cricket bait are key insurance policies. If you’re unsure as to whether these are a concern, put a sack out overnight to detect slugs

Fertiliser

Sow with start up fertiliser
Products such as DAP will give establishing ryegrass plants a great kickstart, as the phosphate is great for root development and the extra nitrogen will help speed things up

Use Treated Seed

Seed treatments such as Superstrike® will protect new seedlings from pressure for the first six weeks from insects such as Argentine Stem Weevil and black beetle adults, as endophyte takes about six weeks to start functioning
Contains a fungicide to protect the seedling from any diseases, as well as micronutrients to aid with establishment
Withholding period for new pasture is six weeks; for undersowing it is three weeks

Cultivar Options

Asset AR37 diploid Italian ryegrass: Robust, high yielding diploid Italian. Great for ease of management over the winter, particularly in wetter areas

- Undersowing rate: 12-15 kg/ha

Mohaka AR37 tetraploid hybrid ryegrass: Dense, high quality hybrid with excellent winter production. Increased persistency over an Italian ryegrass

- Undersowing rate: 18-20 kg/ha

Legion AR37 diploid perennial ryegrass. Dense high-quality perennial with excellent summer and autumn recovery ideal for boosting future summer recovery of an existing perennial pasture

- Undersowing rate: 12-15 kg/ha