Determining in-farm water and nutrient use

Determining in-farm water and nutrient use, incorporation and loss mechanisms on Western Australian grazing properties

Agricultural activities, especially within coastal catchments, such as in this case the Peel-Harvey catchment, can produce off-site environmental impacts particulalrly in terms of contamination of water with excess agricultural nutrients. Additionally, irrigated properties sometimes use inefficient irrigation practices which results in loss of additional water and water-borne nutrients to the broader environment.

This project seeks to determine the extent of these impacts within the context of dryland and irrigated beef and dairy properties in the South West of WA, benchmark them against the performance of catchment partners, other industries and non-agricultural areas, and develop techniques to reduce off-site impacts and maximise farm productivity.

Specifically, the project has three major objectives:

• To understand the processes involved in water and water-borne nutrient use and loss within grazing systems and the potential and actual impacts on water quality of a variety of water and nutrient management best practices.
• To understand the relationships between farm management practices, on-farm water quality and export drainage water quality
• To develop improved understanding of the relative use and loss of water and nutrients at various points within grazing enterprises in an irrigation area and to recommend the most effective ways to increase water and nutrient efficiency.

The project will produce data which will quantify the environmental performance (at least in terms of water and nutrient management) of a number of representative Western Australian beef and dairy farms. There will therefore be direct benefits to local farmers and landholders who use irrigation systems which will lead to improved understanding of the reality of farming in WA among non-grazing groups. It will also lead to a better understanding of how cattle grazing performs in the whole-of-catchment context, resulting in increased water efficiency of grazing industries within the Peel Harvey region.

Ultimately, it will lead to more confident recommendations regarding environmental and enterprise best practice and a more meaningful and positive relationship between the WA beef and dairy industries and the WA natural resource management community. It will also provide robust evidence of sustainable farm management should regulators and (equally importantly) meat and milk markets, require this.

Contact Mark Rivers

A research paper on this subject is available for download below.

Flow control structures such as this Trapezoidal flume are used to measure the flow rates of water moving through and leaving grazing properties. Automatic water samplers are installed with the flumes to allow water sampling to be automatically linked to specific flow events.

Centre pivot irrigation is being compared with conventional surface irrigation in terms of Water Use Efficiency and pasture productivity. Results so far indicate that centre pivot irrigation can produce twice as much pasture as surface irrigation while using only half of the water.