Farm Table says:
This article looks at environmental impacts of raised bed cropping in south west Victoria.
What is the problem?
Raised bed systems have revitalised the broadacre cropping industry in the high rainfall areas of south-west Victoria (Vic). By 2003, there were an estimated 50,000ha of raised beds installed, and potential for 1 million ha wikth high to moderate suitability for raised beds. This project has gathered valuable knowledge on water movement and nutrient losses from raised bed and conventional cropping systems.
What did the research involve?
This project has gathered valuable data on water movement and nutrient losses from raised bed and conventional cropping systems in southern Australia.
Results from the field measurements and modelling indicate that raised beds change the hydrology of the landscape.
What were the key findings?
- economic – results suggest that significant amounts of nutrients, particularly N, are being lost in run-off
- environmental – knowledge of off-farm nutrient loss run-off from cropping systems in Australia is scarce. This project has promoted the importance of the development of cropping systems in the HRZ that maintain water and nutrients on-farm and mitigate off-farm nutrient losses
- social – through the demonstration site at the SFS Concept Farm, this project has increased community awareness about the environmental impacts of raised beds
The project found large differences in run-off based on different soil types and tillage practices. This indicates that a more comprehensive modelling framework is required for raised beds, combining infiltration of the bed surface and traditional furrow drainage theory. Development of a user-friendly model to characterise drainage, run-off and associated nutrient losses under raised beds is recommended. This model could be considered as part of a specialised raised bed module for APSIM. Such development would help lower the amount (and cost) of the field verification required.
Knowledge of soil-water characteristics and soil hydraulic properties is very limited in the southern Vic region. Confidence in the use of the APSIM and other models for south-western Vic would be improved by increasing knowledge of the physical nature of soils in the region.