Although many WA graingrowers lay the blame for high screening rates squarely on high seeding rates, new research suggests this is not necessarily fair.
The research, supervised by Frances Hoyle of AGWEST and supported by growers through the GRDC, offers the good news that growers can use high seeding rates for maximum yield or better weed suppression, without suffering from high screening levels at the business end of the season.
Results in all years, and at all sites with seeding test rates of 30-100 kg/ha on a variety of soil types, showed screenings for most varieties were unchanged or decreased marginally at higher seeding rates.
Time of sowing
The research also confirmed that time of sowing influences grain quality and, as many WA growers can testify, in years of a rapid dry finish, later-sown crops seem to result in more material falling through the sieve at harvest. On the other hand, in wet seasons when there is prolonged rain during grain-fill and ripening, time of sowing seems to have less influence on screening levels.
Other influences for increased screenings include inappropriate nutrition, poor weed control and frost, which many WA growers have, unfortunately, experienced for two years in succession.