The New South Wales Department of Primary Industries (DPI) has concluded an investigation into the viability of adopting centre based pivot and linear move (CPLM) irrigation systems to replace current surface irrigation ion the southern Riverina region.


The study investigated the financial implications of adopting CPLM technology to irrigate winter crops and lucerne for hay in the face of a lack of objective information on the economics of CPLM irrigation.


“We found that CPLM irrigation will be financially viable if the annualised capital costs, plus the associated costs with irrigation, are less than 25% of the projected annual gross income,” NSW DPI Deniliquin based researcher, Sam North, said.


“This is reasonably achievable for summer cropping, but careful budgeting is needed before investing in CPLM for winter cropping only. 


“In the southern Riverina, achievable target yields on suitable soils with sufficient water and good crop management were found to be 6-7 tonnes per hectare for wheat and 18-20 t/ha of lucerne. 


“Irrigations should be scheduled and applied to maximise yield, so if water is limited, it is better to reduce the irrigated area than to apply sub-optimal irrigation depths. 


“Dispersive, heavy clay soils limit the ability to maximise income from a CPLM system as these soils have a propensity to watelog, reducing the likelihood of consistently achieving maximum yields.” 


Mr North said the use of CPLM irrigation had begun to spread in the recent years, spurred on by the ongoing drought and the subsequent low irrigation allocations.


However, Mr North said the study had shown that the use of CPLM technology required significant start up capital investment and was not well suited to all soil types.


“Capital costs make up more than half the annual costs of CPLM systems, so the system needs to be able to supply peak crop water demand and be used as much as possible to maximise income. 


“Growers also need to be aware of the costs involved in operating these systems and design their machines accordingly, particularly given the rising costs of energy."