MANAGEMENT OF FURROW IRRIGATION TO IMPROVE WATER USE EFFICIENCY AND SUSTAIN THE GROUNDWATER RESOURCE—PRELIMINARY RESULTS FROM A CASE STUDY IN THE BURDEKIN DELTA

The Burdekin delta region depends on groundwater for irrigation and urban supply. Therefore, any adverse impacts on the groundwater resource are undesirable. Field studies were implemented to improve knowledge and understanding of impacts of current and modified irrigation management practices on crop water use, productivity and long-term sustainability of the Burdekin delta groundwater system. Field trials were established on six sites representing different soil types of the delta comparing conventional (CONV) and best management practice (BMP) irrigation systems. The BMP applied was site specific, and was determined by consultation with BSES extension officers and the individual grower. Sites were instrumented to measure irrigation application, crop water use and the quality of water draining beneath sugarcane crops. Preliminary results highlight that BMP irrigation reduced the amount of water applied to each treatment by an average 15%. BMP irrigation practice increased yields on three of the six sites by about 6%. Three of the six sites have nitratenitrogen values above the ANZECC long-term trigger value of 5mg/L. There were differing trends in nitrate-nitrogen movement throughout the season, with evidence that nitrate-nitrogen movement is greatest shortly after fertiliser application.