Farmers should consider the possibility of lower yields this year and
fertilize based on realistic expectations, say crop researchers.
A dry fall and winter have left grain farmers in much of Alberta,
Saskatchewan and some parts of Manitoba with little soil moisture.
Brent Flaten, a soil fertility specialist with Alberta Agriculture in
Stettler, said farmers must plan according to their own situations, but
this year the best choice may be to cut back on initial crop inputs.
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Flaten said farmers should fertilize to a targeted yield level, but if
they have seen two or more dry years, they may want to carefully
consider those targets.
“When things are dry and dollars tight, farmers need to be sure of
exactly what they have (in the field) and then start making decisions,”
he said, adding soil testing is more important than ever.
“Lots of growers have been putting on phosphorus for 20 or 30 years.
This year, they may have enough and be able to cut back … crops that
didn’t yield well last year will have left residual (nitrogen). Farmers
may be able to save there as well,” he said.
Brian Fowler, plant breeder and winter cereal researcher with the
University of Saskatchewan, said the university’s test plots have shown
elevated levels of residual nitrogen because of last year’s drought.
“You have to do the spring soil test. In conditions like these very
little can be taken for granted,” he said.
Microbial activity in dry soil is low because of the lack of moisture,
so fertilizer is not easily converted for plant use.
“So until we get some moisture, you need to base your expectations on
true test results,” he said.
“It’s a tough decision to make. You want a good crop, but you don’t
want to tie up money in the soil that won’t provide returns this
season.”
Fowler recommended placing enough nitrogen to start the crop and
provide a reasonable yield based on the soil moisture, plus realistic
expectations of rain.
“If it rains you can always (top dress) the crop with more N,” he said.
Flaten agreed.
“You can add (nitrogen) to the soil after timely rains and before the
flag leaf gets too high and still affect yield. After the flag leaf is
up it will only increase protein,” he said.
Applying nitrogen as anhydrous ammonia can be effective even in dry
soils but only if the soil doesn’t break up and clump too much, he
said.
“The anhydrous can gas off then.”
Top dressing nitrogen before seeding can mean losing nitrogen into the
air if limited moisture is present.
“Banding in liquid (nitrogen) can be very effective, as can granular,
provided it gets it (nitrogen) away from the air,” he said.
Larry Gusta of the U of S said leaving plants short of nutrients can
lead to disease or poor protein levels if timely rains do arrive.
“It’s a double-edged sword. If you fertilize too much and there is some
moisture at seeding then you get too much biomass for the plant to
support if it doesn’t keep raining. That’s a disaster. If you fertilize
too little, you lose the yield, the protein and plants are vulnerable
to disease,” he said.
In some cases, it might be worthwhile to skip seeding completely this
year, said Adrian Johnston, a researcher with the Potash and Phosphate
Institute of Canada.
“For some producers in the really dry areas it will come down to making
a decision about even whether to crop or chem fallow this year. But
most seem to be ready to go to the field and they need to plan for what
they have,” he said.
Flaten said it depends on the producer.
“Are you an optimist or a pessimist? Either way, it pays to be
informed.”
