Inflo eNewsletter

IRRIGATION MATTERS: Soil solution monitoring in Australia

CRC for Irrigation Futures Irrigation Matters Series No. 04/08, Soil solution monitoring in Australia, by Steven Falivene is now available online.

Summary
Although the manufacture and use of soil solution extraction devices for salinity and nutrient management is not a new concept, its use in irrigated cropping has recently increased through the work of consultants and various research and extension projects. Numerous issues are faced by irrigators which include high soil salinity, maximising marketable production, reducing fertiliser costs and reducing environmental impact. Soil solution analysis is a tool that can assist in the managing these issues.

The extraction of water from the soil can be undertaken using two types of devices – active lysimeters and passive lysimeters. Active lysimeters, such as ceramic suction cups, draw water out of the soil through negative air pressure (suction) exerted within the ceramic cup.

Passive lysimeters collect water by redirecting the downward flow of water during irrigation into a collection cup. Passive lysimeters can only collect a sample when a wetting front moves past the device. The FullStop Wetting Front Detector is an example of a passive lysimeter. When a sample is collected it triggers a signal. The signal can also be used to assist in irrigation management. There are some differences in the use and interpretation of results provided by active and a passive lysimeters. Both methods are viable options for sprinkler and drip irrigation systems.

Soil solution analysis is best used in conjunction with other monitoring tools (eg. leaf analysis, soil analysis, visual crop assessment). Adoption of soil solution analysis depends on the necessity. The greatest level of adoption has been from growers facing production losses from soil salinity issues, both annual and perennial horticultural crops. A moderate level of adoption has been by growers of intensive annual crops and a fair level of adoption by growers of perennial crops both of which use soil solution analysis as a nutrient management tool.

The case studies presented in this report demonstrate that soil solution analysis has helped many growers to identify problems before they have had a significant impact. These growers were able to modify their nutrition and/or irrigation practices within the growing season and avert possible crop decline. Soil solution analysis is also a useful environmental management tool to reduce nutrient leaching, however little government incentive or regulation is provided for grower to adopt soil solution analysis for this reason.

A significant barrier to adoption has been the lack of information and training as well as the perceived high cost of soil solution extraction devices. This report identified numerous low cost manufacturers of soil solution extraction devices.

Click on the link below to download the report.

www.irrigationfutures.org.au/news.asp?catID=12&ID=880