WIDER row spacing could be the key to reliable lupin production, year-in-year out, therefore boost profitability.
Farm Focus Consultants principal consultant Geoff Fosbery challenged traditional lupin row spacing head-on at the CSBP futurefarm WANTFA conference last week.
Consistent higher yield trials may have the rule book for sowing lupins rewritten.
Mr Fosbery said demonstrations, plus trials and other paddock observations had encouraged the use of wider row spacing in lupins.
According to Mr Fosbery the yield increases were due to improved light penetration into the canopy, which resulted in superior pod fill.
He said historically lupin yield estimation had been difficult.
Giving an example of a lupin crop in Three Springs, yield was estimated at 2.5-3t/ha, after an average of 70 pods per plant were counted, with 40-50 plants per square meter.
However, the yield was 1.2t/ha because the pods did not fill, which Mr Fosbery suspected was due to lack of light.
At three separate Tanjil lupin trials in Three Springs superior yields were recorded at 20 inch row spacing compared to 10 inch.
In a trial on gritty white sand yield jumped 0.243t/ha from 1.33t/ha to 1.573t/ha, and boosted the gross margin by $54.50/ha, based on $224.26/t port as quoted by the Grain Pool of WA from December 22, 2001 to January 19, 2002.
On a good yellow sandy soil site (same farm) yield increased 0.084t/ha from 2.376t/ha to 2.535t/ha, which produced a gross margin of $18.84/ha.
In another trial conducted on a good yellow sandy soil yield jumped 0.159t/ha from 2.376t/ha to 2.535t/ha, with a gross margin of $35.66/ha.
Mr Fosbery said the wider row spacing improved light infiltration into the canopy, which suggested light could have an influence on pod fill.
In addition, at wider spacing the main stems were longer and bottom pod height higher which improved harvestibility.
With this in mind, Mr Fosbery also suggested sowing direction could influence pod fill.
By chance the trial was sown east/west and where the sunlight hit the plants the least, there were more empty pods.
Spacings of up to 50cm were also trialed, but yield dropped after that width.
Mr Fosbery said plant density needed to be maintained, otherwise weed competition would become a problem.