The Teagasc current recommended seeding rates see below:
Spring Cereal Seeding Rate Calculator 2016 (Excel)
Certified seed offers growers high germination capacity, purity of sample, free of weed seeds within tolerance levels and is treated against seed borne diseases. The DAFM has produced a comprehensive guide on seed certification.
Where seed is home-saved then it is important that it is tested for germination, Micodochium (Fusarium) seedling blight, etc. to ensure that it is suitable for use as seed.
As spring barley drilling dates are delayed, you should adjust seed rates (upwards) to take into account of higher expected estabilishment rates and lower tilering capacity (see chart below)
Use the following calculation to set your drill:
Target Plant Population X TGW
Estimated plant establishment % = seed rate in kg/ha
E.g. if you are drilling Propino with a TGW of 50.9 g and you want to establish 280 plants/m2 with a germination test is 95% and you estimate potential field losses (pests, capping etc) to be 10% then you should drill.
280 X 50.9
85 = 168kg/ha