Decreasing Nitrous Oxide Emissions In High Rainfall Cropping Systems. Hamilton, Victoria, 2009 - 2012 [Theme 1: Inhibitors for reducing emissions]

Brief description

Cropping is expanding in the southern high rainfall zone and
it is important that we provide farmers with management options
that minimise greenhouse gas emissions without reducing
productivity. An increasing proportion of land in the high
rainfall zone is being converted from pasture to cropping, but
the process of changing land use can have significant
ramifications for greenhouse gas emissions. Nitrous oxide
emissions in excess of 3kg nitrogen/hectare/year
(equivalent to 1460kg of carbon dioxide) have previously
been measured at Hamilton, when a high fertility legume
dominant pasture was converted to a cereal crop. The purpose of
this project is to test management and mitigation options that
could reduce the nitrous oxide emissions that are
released during such a landuse change. We are testing
the effect of soil tillage and also a chemical that
inhibits the bacteria involved in the soil nitrogen cycle.
Nitrous oxide emissions from conventionally cultivated soil are
being monitored compared to direct drilling of the crop.
The application of a nitrification inhibitor
(dicyandiamide - DCD) is also being trialled. DCD
temporarily disrupts the process by which microbes
convert ammonium to nitrate, slowing the production of nitrate
and reducing nitrous oxide emissions from the soil.
Automatic gas collection chambers connected to a
tuneable diode laser are used to measure nitrous oxide
release from the soil. The chambers close 16 times
throughout the day for 30 minute intervals to collect nitrous
oxide gas. Carbon dioxide levels are also measured within the
chambers while remote sensors log soil moisture and temperature.
The chambers are moved to different locations within 12 trial
plots to minimise any interference to the natural
pattern of crop growth. A comprehensive dataset will be
developed for input into a national greenhouse gas model
and for use in producing scientific publications that
will contribute to the Australian National Greenhouse
Gas Inventory.