Malting barley thousand grain weights essential to seed rate

By Eoin Lyons, Teagasc/Boortmalt Joint Programme advisor

This year, depending on location, there will be three spring malting barley varieties being distributed by Boortmalt. They include: Planet; Laureate; and Prospect.

If drilling any of these varieties it is important that the correct seeding rate is used in order to reach the target plant population/m².

To maximise spring malting barley grain yield, aim to drill 350 seeds/m² which assuming an establishment rate of 85%, should produce 300 plants/m².

By establishing 300 plants/m², the spring barley crop will have a good opportunity of producing a large number of shoots and ears to produce a high yield.

Thousand grain weight is essential

To determine the correct seeding rate to use in order to hit the 350 seeds/m² target, we firstly need to determine the Thousand Grain Weight (TGW) of the seed.

This will be displayed on the side of the seed bag.

The TGW of seed this year is relatively constant among seed lots, unlike last spring when there were considerable differences even among the same variety. The table below shows the average TGW for the three main malting barley varieties.

Varieties and their TGW figures:
  • Planet – 52g;
  • Laureate – 52g;
  • Prospect – 45g.

Once the TGW is determined the seed rate can be calculated using the following equation.

The TGW should be multiplied by the target plant population/m² and divided by the expected establishment percentage (85%). This will give the seed rate (kg/ha).

While TGWs are more uniform this year, it is vital to examine the TGW on the seed bag and use the above formula as there can still be differences.

Difficult sowing conditions

Trial work carried out in Teagasc Oak Park has shown that early drilling generally results in higher yield and lower protein in good seedbed conditions.

Unlike some other crops, spring barley that is drilled into a cold wet soil will inevitably suffer a yield penalty; therefore, it is vital to allow the current saturated soils time to dry out fully before ploughing and drilling.