Direct land application of organic and/or inorganic materials can involve the application of wastewater solids, sludges, biosolids or macerated food waste directly to the land. The direct injection of liquefied material into soil is a method of treating such materials.

Research into direct soil injection indicates that this process can increase soil organic matter and the availability of nutrients in soil and may also increase soil microbial activity. However, as the food materials are not pasteurised or processed in any way, there is potential for the transfer of pathogens to plants and animals, and for phytotoxic effects to plants and/or attraction of flies and vermin to application sites.

As food organics materials are putrescible and can be relatively high in nutrients and salts, direct land application must take care not to cause negative environmental impacts via odours, attraction of pests, soil salinity and/or leachate into rivers or groundwater.

More information on direct soil injection can be found in the report 'Food Organics Processing Options for New South Wales' available free for download.

Direct land application of biosolids in New South Wales must be performed in accordance with the 'Environmental Guidelines: Use and Disposal of Biosolids Products' developed by the NSW EPA (1997). Visit www.rolibrary.com for more information on these guidelines.