Information
Level 2: Detail of Experimental Conditions and Methods
What?
The project objectives were to measure the lost of nutrients and pesticides in surface drainage water from irrigation sugarcane farms and to quantify those input/losses by measuring inflow and outflows. This would allow identification of practices that reduce/minimise environmental risk and extension of those to the industry.
Broadly the objectives of the study include:
- Measure irrigation water entering canefields and leaving by surface drainage for several cane farms in the Burdekin River Irrigation Area (BRIA);
- Quantify sediment, nutrient and pesticide input and outflow in irrigation and surface drainage water for these farms;
- Identify nutrient and pesticide movement through the soil profile by strategic core sampling;
- Identify practices that reduce / minimise environmental impacts; and
- Extend these measures to industry.
When and Where?
Nine farms were chosen at random for monitoring to be conducted. A tenth farm was commenced but abandoned. The GPS location of the discharge site on farm 3R is Northing 55 78 06 577 and Easting 5 17 937.
The farm had an area of runoff 227.1 ha.
How?
Nine farms were chosen at random will the monitoring of a tenth farm commenced but was abandoned. A rain gauge was installed at each drainage site to collect data specific to the location being monitored.
Drainage water samples were collected using ISCO 3700 programmable autoi sampler. Sampling event were triggered by water levels sensors, set to initiate sampling 1 minute after farm overflows commenced. Spot samples were collected from irrigation inflows for nutrient, pesticide and turbidity analyse.
The handling of the samples included:
- Each sample had a small amount of sodium thiosulfate solution added for sample preservation;
- One of the samples were used as a break down sample with the others samples a few drops of 0.1% phenyl mercurie acetate were added to each bottle to prevent biological breakdown of nitrate and ammonium-nitrogen.
Analyses for ammonium-n, nitrate-n, phosphorus, sulfur, potassium, calcium, magnesium and sodium were carried out at BSES Indooroopilly and the result were reported as mg/L of the element.
Pesticides were analysed by BSES Indooroopilly and subsequently by Environmental Consulting at Oakley Victoria.
Farm inflows were determined by measuring the discharge rate of pumps or flow rate in fluming and elapsed time of delivery. Outflows from each farm were measured via a single installed structure as part of the dam design, these structures were converted to (Cipollettin / broad crested) at which the height were measures using a calibrated float systems.