In Yanco's centenary year, in hotter than desired temperatures, based on the season’s irrigation allocation for Murrumbidgee, researchers have surprised themselves by cracking the irrigated wheat "ten tonne club".

This had led them to the big prediction of an exciting future and new levels of profitability for irrigated wheat.

Wheat variety trials in a 2007 Grains Research and Development Corporation irrigated cereal variety evaluation project averaged close to 10 tonnes a hectare, with the most revealing result that the popular commercial durum wheat variety, Bellaroi, averaged above 10t/ha.

A number of new genotypes yielded above 10t/ha.

The commercially released bread varieties such as Chara and Giles still yielded nine tonnes a hectare.

"Average temperatures in the post flowering period from the second to the last week in October averaged 20 degrees, so it was surprising the yields were so high," NSW DPI Industry rice farming systems leader, John Lacy, said.

"This was well above the desired 14 degrees, considered conducive to high yields."

NSW Department of Primary Industries (DPI) researcher, Andrew Milgate, used the key checks in the department’s "eight tonne club" package in evaluating genotypes and identifying new higher yielding varieties.

They applied extra nitrogen and fungicides to target the 10 tonne threshold but Mr Lacy said profitability would have been even higher for farmer crops, since both inputs would be lower.

Based on the average yield of the three trials at 9.8t/ha and wheat price of $350 per tonne, the income per hectare was $3430.

The variable cost was $1650/ha based on current herbicide, fungicide and fertiliser prices.

The irrigation cost was $90 per megalitre, based on the 2007-08 season irrigation allocation of 13 per cent for Murrumbidgee Irrigation and included farm fixed and variable water costs.

Mr Lacy said the gross margin per hectare was a profitable $1779.

"For the total pre-irrigation and spring water use of 5.3 megalitres a hectare, the gross margin per megalitre was $336," he said.

"Using the same costs, the gross margin per megalitre for eight tonnes was $255."

If budgets were calculated on normal irrigation season water costs, the gross margin per megalitre for 10 tonnes would rise to $395.

The trials were conducted in a border check layout following a break crop of canola with a previous history of lucerne.

The red loam soil site was pre-irrigated with 1.7ML/ha and deep soil nitrogen tested.

The soil nitrogen was 70kgN/ha so this was topped up with fertiliser so the total nitrogen at sowing was the recommended "eight tonne club" check of 120kgN/ha.

The nitrogen at sowing was deliberately limited to reduce the chance of excessive vegetative growth and potential for lodging.

Sowing fertiliser was 120kgMAP/ha.

The sowing date was May 15 and the 100 kilogram per hectare sowing rate resulted in the target plant population of 160 to 200 plants per square metre.

At the first node stage the shoot populations of most varieties averaged a high 780 shoots/m2, which does not normally require nitrogen topdressing for eight tonnes.

Since the target yield was 10t/ha, 68kgN/ha was topdressed at the end of July, just ahead of nine millimetres of rain.

A second topdressing of 110kgN/ha just before the awns visible stage was applied just ahead of the second spring irrigation on September 18.

Delaying the second nitrogen topdressing, making it the major topdressing stage, helped to reduce lodging and diseases.

The timeliness of irrigations was a major factor in obtaining the high yields.

Soil moisture was monitored with an enviroscan and gypsum block Hansen loggers.

Five spring irrigations were applied with the first irrigation on August 30 using 0.8ML/ha with 0.7ML/ha for each subsequent irrigation.

Thus the total spring irrigation water use was 3.6ML/ha.

Since the aim of the project evaluation was to target maximum yields, three preventative stripe rust applications of propiconazole fungicide were applied on the September 7, October 5 and November 9.

The eight tonne package aimed to reduce the risk of early lodging which has been a major factor preventing consistent eight tonne wheat yields.

In two of the wheat trials, lodging was post flowering and had no effect on yield.

However in the main wheat trial earlier, lodging after flowering resulted in reduced yields for lodging prone genotypes.

The Growing eight tonnes of irrigated wheat in southern NSW Primefact is available from NSW DPI offices.

Contact John Lacy, Yanco (02) 6951 2738, 0427 311 821.