GHG Implications of no-till irrigated farming systems - Keytah
Abstract
Keytah is an irrigated cotton and grains farming operation west of Moree in Northern NSW. The
total area of the property is 24 000 hectares of which 10 400 hectares is irrigated cotton, grown in
rotation with wheat. During a normal season only half of the irrigated area is cropped at any one
time with the other half maintained as a bare fallow. The farming system includes a summer cotton
crop, planted in October and followed by a winter wheat crop planted in May and harvested in
November. After the winter wheat crop a fallow of approximately 12 months takes place before
cotton is replanted back in October. The farming system incorporates 60” beds where cotton is
usually grown in two rows 30” apart or more recently in a single row where water supplies are
limiting. In comparison the wheat is grown in 4 rows on the same 60” beds at a spacing of 15”.
Regardless of the planting system adopted different plant lines are maintained between the summer
and winter crop options. All tractors have been extended to operate on 120” (i.e. 3 m) centres.
In a normal irrigation season Keytah relies on 7 to 7.5 ML/Ha of water for irrigation which is applied
by surface (furrow) irrigation and two lateral move irrigators. Water is sourced from the Gwydir and
Mehi Rivers and is pumped into on farm storages before being distributed to the field for irrigation.
In response to limited irrigation supplies (1 ML/Ha) in 2007 / 2008, a radical change in farming
practices is currently being pursued to establish and produce a cotton crop. Previously the variation
in soil properties across the farm has been identified via an EM survey. This survey was conducted
when the soil was relatively close to field capacity. In an attempt to identify fields which had
adequate soil moisture for planting cotton, an EM survey of the farm was again conducted to
identify areas of high soil moisture content. The EM survey identified 2 fields side by side where one
field had an estimated increase in soil moisture of 40% soil moisture. This increase in soil moisture
was attributed to no tillage over the fallow period.To assess the benefits of farming system changes in terms of energy and GHG emissions, 3 scenarios
were developed from actual crop history data and evaluated using the energy assessment software,
EnergyCalc.developed by the National Centre for
Engineering in Agriculture to assess total on farm energy use and the associated GHG emissions. The
three scenarios that were developed to assess farming practices on Keytah included:
i) a benchmark of energy use from 2000,
ii) current practices or reduced tillage and
iii) progression towards zero till farming methods
Each scenario was developed from previous farm records of field K8 (in 2000) and current crop
records of K8 and C16 (reduced tillage) and K13 and C17 (towards zero till). Farm practices were also
confirmed via an initial site visit.
This item appears in the following categories
- 2009 Final Reports
CRDC Final Reports submitted in 2009