Proceedings

The effects of organic matter (OM) additions from farm manures and biosolids on soil physico-chemical and bio-physical
properties were determined at 11 experimental sites, with a history of repeated farm manure or biosolids applications.
Repeated and relatively large OM inputs were needed to produce measurable changes in soil properties (particularly physical
properties). However, at the farm manure sites, there was a positive relationship between OM inputs and changes in total soil
organic matter (SOM) and ‘light’ fraction organic matter (LFOM), with the LFOM providing a more sensitive indicator of
changes in SOM status. Both farm manure and biosolid organic matter additions decreased soil bulk density, but increased
porosity and available water capacity (AWC). Farm manure additions also increased both the size and activity of the microbial
biomass and the size of the potentially mineralisable N pool. However, these soil quality benefits need to be balanced with
any potential environmental impacts and sustainable crop production aims.