Reducing on-farm nitrous oxide
emissions through improved
nitrogen use efficiency in grains
Action on the Ground demonstration project
Project aim
The project aims to trial, measure and demonstrate on-farm practices and technologies
to reduce agricultural greenhouse gas emissions. The principal method for achieving
reduced emissions is to improve crop utilisation of nitrogen derived from both soil and
fertiliser sources. Improved utilisation of both soil and fertiliser nitrogen will improve crop
productivity, whilst potentially leading to reduced nitrous oxide emissions from the soil.
Project background
Recent research has highlighted the potential
for large nitrous oxide emissions in Victoria’s
medium and high rainfall (and potentially
irrigated) cropping systems. These emissions
are believed to result from the large
background levels of soil nitrogen and carbon,
coinciding with temporary periods of high
soil water. Nonetheless high rates of fertiliser
nitrogen are often applied because of concerns
that the available soil nitrogen cannot meet
crop demand, however predicting the efficacy
of such applications can be difficult.
There are two key issues when predicting
potential responses to nitrogen fertiliser
application:
1. Nitrogen supply from in-season
mineralisation of organic matter can
represent a significant proportion of crop
nitrogen requirements. This is particularly
true in medium and high rainfall systems
(and presumably irrigated systems) based
on clay soils, but predicting this supply
can be difficult.
2. Crop nitrogen utilisation coefficients (the
proportion of soil/ fertiliser nitrogen used
by a crop) can vary across regions and
seasons and can also be difficult to predict.
This project will trial and demonstrate to
grain growers methods for rapidly estimating
in-crop nitrogen mineralisation, to better
guide the application of fertiliser nitrogen.
It will also develop crop nitrogen utilisation
coefficients so that grain growers can make
better assessments of the how much of
the nitrogen fertiliser they apply is actually
used by the crop. This information can then
be used to assess the amount of fertiliser
nitrogen remaining in the soil for use by
subsequent crops or lost from the system.
The trials will be conducted on dryland and
irrigated cereal crops but results may be
further tested on canola and other crop
types in the future.
Project objectives
Project design
1. To investigate the practical
application of soil analyses
for predicting potential soil
nitrogen mineralisation, including
hot potassium chloride (KCl)
extraction and mid-infrared (MIR)
spectroscopy. By better accounting
for the ability of the soil to supply
nitrogen during the growing
season it is anticipated that this
information could potentially
improve growers’ ability to match
nitrogen supply to crop demand.
Nine trial sites will be established and managed
during the first two growing seasons (2013-14
and 2014-15), with the number of trial sites
reduced to six for the third growing season
(2015-16). Three nitrogen treatments will be
applied at each trial site: no nitrogen (control),
moderate and high nitrogen fertiliser application
rates (dependent on industry best practice). The
treatment plots will be replicated twice, with
each plot measuring approximately 40 m2.
2. To develop localised nitrogen
response curves for each of the
trial sites in order to improve
grower nitrogen management
decisions. That is, improve grower
understanding of the proportion
of fertiliser nitrogen that is utilised
for crop production or retained
for future seasons under various
seasonal conditions.
Nitrogen fertiliser applications will be
undertaken during the season and timed
according to industry best practice for the
particular region and seasonal conditions.
Where anticipated yields are higher under
favourable seasonal conditions, applications
late in the season will be considered in
conjunction with farmer practice for the
broader paddock and results of pre-season
soil testing.
Data to be collected at each trial site will include:
• Recent land use history
• Pre-season and post-harvest soil testing to
a depth of 1.2 metres
• Measurement of nitrous oxide emissions
from key treatments
• Recovery of applied fertiliser nitrogen from
the high nitrogen rate treatments
• Crop measurements will include:
DEPI Grains Research and Development
Officer Ashley Wallace measuring nitrous
oxide emissions during crop growth.
-
Plant density post crop emergence.
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Biomass cuts taken at flowering and grain maturity to measure grain yield, nitrogen uptake and key grain
quality indicators.
Project area
Demonstration trial sites will be
established on eight farms across the
North Central, Glenelg Hopkins and
Wimmera CMA regions of Victoria and
the Sustainable Cropping Rotations
in Mediterranean Environments
(SCRIME) long-term rotation trial site
at Longerenong, with trials conducted
over three growing seasons.
The project is a joint initiative
of the North Central Catchment
Management Authority (CMA) in
partnership with the Department of
Environment and Primary Industries
(DEPI), Glenelg Hopkins CMA and
Wimmera CMA. The project is funded
by the Australian Government’s
Department of Agriculture and the
Victorian Government’s Department of
Environment and Primary Industries.
Trial sites are located throughout the North
Central, Wimmera and Glenelg Hopkins
CMA regions of Victoria
Project results and further information
Trial sites have been established and initial measurements collected during autumn and early winter 2014. Project results will be
shared at field days and information sessions over the life of the project. For further information about the project please contact
Ashley Rogers at the North Central CMA on 03 5448 7124, email [email protected] or visit www.nccma.vic.gov.au.