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May 12, 2003
TOPCROP West is planning a number of workshops and on-farm
trials to help growers learn more about using nitrogen
fertiliser to manage wheat protein levels.
Western Australia
Department of Agriculture development officer Jeremy Lemon
said the TOPCROP State Focus program was aimed at encouraging
growers to develop a nitrogen strategy based on crop rotations,
seasonal conditions and expected yields.
"Most of the nitrogen required by crops has traditionally
come from legume residues and soil organic matter," he said.
‘However, as cereal yields increase and the proportion of
legumes used in crop rotations declines, increased nitrogen is
required to maintain grain protein at an acceptable level."
Mr Lemon said nitrogen fertiliser management would be
increasingly important this growing season due to large areas of
the wheatbelt having stored soil moisture of between 30 and 70
mm.
"Higher soil moisture content means a higher yield
expectation, and the need for increased quantities of nitrogen
fertiliser to maintain grain protein," he said.
" For example, cereal yield
potential increases by 20 kg/ha for every millimetre of stored
soil moisture. If there is 40 mm of stored soil moisture, an
extra 800 kg/ha of grain grown will need an extra 25 to 35 kg/ha
of nitrogen to maintain grain protein at 10 per cent, depending
on fertiliser efficiency."
Mr Lemon said some of the extra nitrogen required would come
from increased mineralisation of organic matter in wet summers.
"By using nitrogen decision tools such as the Nitrogen
Calculator, farmers can estimate the effect of summer rainfall
on soil nitrogen supply, and additional nitrogen may not be
needed at sowing.
"Although, post sowing applications of nitrogen fertiliser
should be increased to take advantage of favourable seasonal
conditions.
" The State Focus
activities will provide farmers with more confidence in managing
their wheat protein levels through nitrogen applications."
Workshops will look at issues such as the effect of grain
protein on wheat quality, nitrogen supply and dynamics in
cropping systems, and learning how to use available nitrogen
decision tools.
Wheat protein trials may be as simple as top dressing or
spraying rates of fertiliser on established crops, or evaluating
new liquid products.
"Farmer trials from around the state will be reported in a
wheat protein publication early next year," Mr Lemon said.
Grower groups interested in participating in the learning
focus should contact their local TOPCROP support officer or
their local Department of Agriculture farming systems
development officer. |
