TRAMLINE farming offers improved gross margins of about $30/ha in the year of deep tillage and average annual benefits of about $40/ha from a wheat, lupin, wheat and canola rotation on the northern sand plain.
According to Agwest research engineer Dr Paul Blackwell, most of this benefit comes from compaction control.
"A smaller but consistent benefit comes from reduced overlap using a precision guidance system," he said. "Extra benefits can come from inter-row weed control in lupins calculated at about $50/ha compared to green manuring".
Dr Blackwell said the costs of conversion to tramline farming will vary widely between farms so it was important to estimate the value and timing of benefits to better plan financing of modifications and equipment purchases.
Four seasons of farm-scale evaluations had helped develop and calibrate a model of the effect of different machinery systems on compaction, crop production and gross margins.
These benefits were based on a common example of cropping machinery which had a sprayer three times the width of a seeder and a spreading width of twice the seeder width.
Unrestricted yields of wheat, lupins and canola were 2.5t/ha, 1.5t/ha and 1t/ha respectively, with corresponding prices of $180/t, $140/t and $300/t.
Financial benefits came from reduced fuel use, reduced overlapping of inputs and less compaction.
An interesting aspect of Dr Blackwell's work on tramline farming is his comparison to re-ripping.
If the soil on the trial sites had been re-ripped in the second wheat year for a response of 30pc (83kg/ha), this would have been worth $150/ha less about $30/ha costs.
This is an extra gross margin of $120/ha in the second wheat year. The trials showed there was no net benefit of re-ripping the normal traffic system compared to adopting tramline farming.
Current experimentation shows that shields and an in-row chemical treatment can control up to 98pc of ryegrass in the lupin year and allow a profitable crop of lupins without the use of grass selectives.
In comparison to green or brown manuring, the crop can be a gross margin improvement of $150/ha in the lupin year and $50/ha including the following wheat year.
"Such large financial benefits, from equipment that some farmers have made themselves at low cost, is attractive to put at the start of a conversion to tramline farming to help finance the changes more efficiently," Dr Blackwell said.