Agriculture Reference
In-Depth Information
Fig. 7.12 Effect of compost application on microbial biomass carbon in soil samples collected at
time of planting in a long-term vegetable field trial (data shown for 5 out of 7 crops grown, SE bars
shown). (Adapted from Donovan et al. 2014 ). Conventional farmer practice treatment (inorganic
fertilizer and poultry manure)
7.3.3
Contaminants Issue
The composts used in the long term compost-vegetable field trial at CROA were com-
posts made from source separated garden organics waste (i.e., domestic grass clippings
and pruning's) and chicken manure, and these composts met the Australian Standard
(AS4454) for composts, which meant they were low contaminant composts. To protect
food quality and human health, it is imperative that the composts that are applied to
agricultural soils are low in chemical contaminants such as heavy metals and pesti-
cides which can persist in the environment. Separating waste streams at the source (i.e.,
waste generation and collection point) and government regulation can help to achieve
this. Composts made from non-source separated mixed municipal solid waste streams,
should generally be avoided, as they often contain high levels of contaminants. How-
ever, the organic food scraps component of domestic municipal solid waste, if kept sep-
arate from other wastes at the household collection point and then all the way through
to composting (i.e., to minimise contaminant levels), has great potential as an input for
compost production.
7.4
Conclusions
It is apparent from the results of the field experiment at CROA, that the application
of compost at large rates (i.e., > 62 dry t ha −1 ) can significantly improve a number
of measures of soil quality (physical, chemical, and biological), and that such im-
provements can result in yield benefits for certain crops, with positive economic
outcomes for farmers. Environmental benefits from incorporating compost inputs
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