Emerald Irrigation Area cotton growers are researching their winter crop rotation options by undertaking on-farm trials to investigate optimum irrigated wheat and chickpea planting times and chickpea row spacing configuration.

Department of Primary Industries and Fisheries cotton development extension officer, Susan Maas, said a meeting of grower members of the Cotton Growers and Irrigators Research and Technical Committee called for the trials to identify potential yield penalties by planting early or late in the season.

Ms Maas said the increasing emphasis on injecting profitable grain and pulse crops into the Emerald irrigators' cropping rotation calendar reflects a move away from cotton monoculture.

"There has been significant research into irrigated wheat performance in southern cropping areas while the bulk of the Central Queensland chickpea research has focussed on broadacre cropping technology," Ms Maas said.

"These local trials will give our growers an insight into what yield penalties they can expect to incur, particularly for the later planted crops."

Buoyed by a 100pc water allocation, Ms Maas has overseen the wheat and chickpea planting date trials on the Brosnan family property, Emerald Downs, and the chickpea row spacing configuration trials with Hamish Millar, Tandawanna.

Michael Brosnan has planted Strzelecki variety wheat at 80kg per hectare and Moti variety chickpeas at 60kg/ha into four rows on 2 metre beds. Each 5.5ha irrigated trial block was replicated four times with all planting operations undertaken mid-month in April, May and June using an 8m Garnel planter.

"Our April trial blocks were all planted dry and watered up with a 100mm irrigation application but the May and June trials were sown following timely rain," Mr Brosnan said.

"The chickpea blocks were pre-plant fertilised with 30kg/ha of sulphate of potash and 30kg/ha of superphosphate followed up with a water injection of 45 litres/ha of compost tea and 2L/ha of Easy N during planting operations.

"Our pre-plant fertiliser for the wheat trials was 100kg/ha of sulphate of ammonia, 50kg/ha of superphosphate and 20kg/ha of potash followed by a planting application of 40L/ha of compost tea and 10L/ha of Easy N."

The wheat trial paddock was previously planted to mungbeans that were harvested in March this year. Despite being drenched with 550mm of flood rain during two weeks from late January, the mungbeans still managed to yield 2.5t/ha.

Broadleaf weeds and mungbean seed regrowth in the 2008 wheat planting date trials was sprayed with MCPA on June 23.

Mr Brosnan said he used compost tea, a locally produced biological product, for the first time last year to compare yield performance of rain-grown wheat planted with conventional solid fertiliser treatment against a compost tea fertilised block.

A wet winter last year held up a proposed May wheat planting to mid-July and the resultant 80ha low yielding crop averaged only 2.5t/ha. The compost tea fertilised wheat block yielded just 0.1t/ha less than the conventional fertiliser treatment with no difference in wheat quality or grade.

"Given that the compost tea cost equated to about one-quarter of the price of solid fertiliser, the return on investment from my limited farm trial favours the biological fertiliser treatment," Mr Brosnan said.

Ms Maas said that the irrigated chickpea trial row spacing configuration trials being run in cooperation with Mr Millar was targeting optimum yield across differing bed widths and row spacing within beds.

All the 2008 wheat and chickpea irrigation trial results would be reviewed later this year and made available to Emerald irrigators.