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Background and Objectives:
Manitoba has been producing grain corn since the
1970’s and is the leading Canadian grain corn-producing province west of
Ontario. Grain corn acreage has ranged up to 225,000 in the early
1980’s, with 100,000 to 140,000 acres annually in more recent years.
Current expectations are for an immediate increase of 20,000 to 25,000
acres in 2003 and smaller annual increases up to approximately 200,000
acres. Annual cash receipts for grain corn have exceeded $25 million in
recent times. In the past grain yields have fluctuated but in recent
years, with improved hybrids for the cool and short growing season and
the development of new agronomic techniques, yields have tended to be
more stable. Further, with evidence of climate change such as
increasing temperature, moisture and sunshine hours in Manitoba, corn
grain yields have increased dramatically. In 2001 the provincial
average grain yield was 107 bu/acre and in 2002 it was 100 bu/acre. In
order to monitor climate change and its impact on agriculture it is
essential that we continue to collect CHU readings and take advantage of
the positive agro-climatic trends that may occur in the province.
Manitoba corn has a ready market
within the province and western Canada, reducing the dependence on
importation of U.S. corn and the flow of cash to the U.S. Most of
Manitoba’s corn grain is used for feed and for production of alcohol
(whisky). The Diago, Gimli alcohol distillery obtains approximately 80%
of its corn from Manitoba producers. Recently the Mohawk distillation
plant at Minnedosa has been using Manitoba corn for ethanol production
to be used as a blend with gasoline. Research has shown that
ethanol/gasoline fuel blends are cleaner burning and less damaging to
the environment than gasoline alone. Manitoba farmers are in a unique
position to develop and take advantage of the new biofuel markets that
are presently available and scheduled to come on stream in the near
future. Biofuel production will provide a value added element to the
economy of rural Manitoba both in terms of revenue and employment.
Over the past 30 years Manitoba corn growers have
developed expertise in grain corn production. They have been sensitive
to environmental stewardship in applying technology imported from
Ontario and the U.S. The Manitoba Corn Growers Association administers
a "check off” fund that is being used to carry out applied research and
to “proof” new technology as it is introduced in the province. The
research carried out by the Manitoba Corn Growers Association with the
support of this ARDI grant, the cooperation of Manitoba’s
Agrometeorological Centre of Excellence (ACE) and Manitoba Agriculture
and Food agronomists, have demonstrated that there is an excellent
potential to expand grain corn production outside the traditional corn
growing region and to significantly increase grain yield and quality of
Manitoba corn. With the advent of climate change, agriculture in the
province is in a position to experience excellent benefits in terms of
high quantity and quality grain corn production. To profit from this
reality and increase the value-added processing of corn through domestic
feed milling, distillation for human consumption and fuel blends,
research and technology transfer must continue in key agronomic areas.
The objective of this project is to enhance the
productivity of grain corn, grower competitiveness, industry
sustainability, and environmental sustainability through:
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Improved understanding of fertilizer responses in
relation to weather variables, and improved fertilizer rate/management
recommendations.
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Identification of optimum planting density for new
generation hybrids.
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Improved selection of hybrids and improved timing
of management operations through evaluation/development of a Manitoba
corn heat unit (CHU) model.
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Provide new herbicide options, enabling better
weed/herbicide management, more effective herbicide rotation and
reduced risk of herbicide resistance, and ultimately to reduce overall
herbicide load.
Procedure
and Project Activities:
Field experiments were conducted in 2001 and 2002.
All tests were seeded in May in 30” row spacing and at standard corn
seeding depth. Except for the planting density tests, the plant
population for all other tests was 24,000 plants per acre. Similarly,
but for the herbicide tests, weed control was performed using a
combination of herbicides and hand weeding as required. At each site
CHU data was collected and processed by ACE Carman office.
Fertilizer Responses in Relation to Weather
Variables
Field tests were located at Reinland and Carman in
2001 and at Graysville and Edwin in 2002. All sites were analyzed for
organic matter (OM), nitrogen (N), phosphorus (P), potassium (K) and
zinc (Zn) prior to seeding. Rates of N, P, K and Zn were evaluated at
all locations as measured in grain yield, grain moisture, bushel weight,
stalk breakage and root lodging. Fertilizer rates (lb/ac) used were: N
= 0, 50, 100, 200; P = 0, 20, 40; K = 0, 40; Zn = soil applied vs.
foliar application.
Optimum Planting Density for New Generation
Hybrids
Three hybrids of varying CHU ratings were grown at
four different plant densities in Carman and Reinland in 2001 and in
Graysville and Reinland in 2002. The hybrids were 39W54 (2100 CHU),
39T68 (2250 CHU), and 39A26 (2350 CHU). Each hybrid was seeded at a
plant density approximately two thirds greater than the target density
and was later thinned after emergence to achieve the desired plant
densities of 18,000, 24,000, 28,000, and 36,000 plants per acre. The
sites were seeded in May in 30” row spacing. Plots were fertilized
according to soil test results. The data collected included yield,
moisture content at harvest, density, and stem breakage.
Hybrid Selection and Evaluation/Development of a
Manitoba CHU Model
Annually 55 to 60 corn hybrids were evaluated at four
locations in the traditional corn-growing region of Manitoba, and at a
fifth location in western Manitoba (non-traditional corn region) 20 to
25 hybrids were evaluated. The hybrids were evaluated, under conditions
of recommended plant population, for days to emergence, days to tassel,
days to silk, days to maturity, grain moisture at harvest, and clean
grain yield at 15.5% moisture. At each location, under contract with
ACE, environmental data were collected and CHU calculated. The
accumulated CHU values were compared with crop physiology and growth
parameters measured and recorded on several hybrids with different CHU
rating at three locations to assess the validity of using accumulated
CHU to determine the hybrids that are suitable to be grown in a region.
Enhanced Weed Management
Accent (nicosulfuron) received Minor Use registration
in 1998 for use in Manitoba but only one registered tank mix is
available, with Banvel at 0.6 L/ha (0.24L/acre) + non-ionic surfactant
(NIS). Ultim (rimsulfuron + nicosulfuron) received Minor Use
registration in 2002 for use in Manitoba on four hybrids only, and no
registered tank mixes are available. Both herbicides were used in the
study alone and in tank mixes with other herbicides and additives (NIS,
Merge and urea ammonium nitrate) to assess efficacy and crop tolerance.
Accent tests were conducted in 2001 and 2002 at Fontaine and Reinland
using the hybrid DKC 29-95. The Ultim tests were conducted in 2001 and
2002 at Graysville and Reinland using the hybrids 39M27 (Bt) and 39W54
(non-Bt). Weed control efficacy and crop tolerance were rated at 1, 2
and 4 weeks after spraying. Final grain yield corrected to 15.5% moisture was
also collected.
Results and Discussion:
Fertilizer
Application of fertilizer N increased yield
significantly at the Edwin and Reinland sites in both years but because
of high residual soil N at the Graysville site there was no response.
The use of the SPAD meter correctly identified the Edwin site as
responsive to N and the Graysville site as having sufficient N, which
was confirmed by soil analysis for available and mineralizable N.
Increasing N rates had no effect on grain test weight but increased root
lodging and stalk breakage and resulted in lower grain moisture at
harvest. There was no response to banded potash, even on the Edwin
site, which had low soil potash, but applied zinc significantly
increased yield at one site and showed a similar trend at 2 other
sites. Yield response was more likely with the soil-banded zinc and
occurred across a range of soil test values. Also, banding of 40 lb/ac
P2O5 to the side of the seed at seeding increased
grain yield by an average of 6 bu/ac. The 20-lb P2O5/ac
rate was insufficient to promote a yield
response.
Plant Population
At all four site-years corn
hybrid had a bigger influence on grain moisture and density than plant
population. The hybrid 39W54 consistently had the lowest moisture
content and highest density in comparison to 39T68 and 39A26. This was
due to 39W54 maturing earlier than the other two hybrids. Increasing
the plant population significantly increased grain yield at three out of
the four site years, but it had no effect on grain moisture except at
Reinland in 2001 when an increase was observed. Similarly, increasing
the plant population had no effect on grain density and thus no negative
effect on grain quality. Stem breakage increased with increase in plant
population, however at the Reinland (2001) and Graysville (2002) sites
stem breakage did not decrease the grain yield, indicating that the
increase in yield due to increasing plant density overcame any yield or
harvest losses as a result of stem breakage. Generally, there was no
interaction between hybrid and population for yield, moisture, density,
or stem breakage at all four site years, indicating all three hybrids
responded similarly to increases in population.
Manitoba corn producers may be able to realize an
increase in yield by increasing their plant population. The two-year
study conducted by the Manitoba Corn Growers Association indicated that
increases in yield were possible up to 36,000 plants per acre without a
decrease in quality or an increase in moisture content or stem
breakage. The study also showed that the three hybrids studied could
handle the increases in population. However, hybrid choice played a
large role in determining moisture content at harvest and density.
Evaluation/Development of a
Manitoba CHU Model
The three main climatic
variables that affect adaptation are day-length, temperature (both heat
and frost-free period), and rainfall. Day-length and temperature affect
development, i.e., flowering and maturity; and temperature and rainfall
affect growth, i.e., yield. Short day-lengths make corn develop more
quickly but day-length is of minor importance for an adapted hybrid
because it only has a slight effect for 15-25 days after emergence. Air
and soil temperatures are very important because the rates of growth and
development increase as temperatures increase from 10 to 30ºC (50-86ºF).
In early spring, soil temperature is more important than air
temperature because the growing point stays below the soil surface until
sometime in June. For most of Canada, temperatures are usually too low
for corn rather than too high. This is why cumulative temperatures such
as CHU are closely related to development. CHU are better than calendar
days for measuring time between stages because, in warmer regions, more
CHU are accumulated per day so that corn develops faster per day than in
cooler regions.
Although there were
variations in days to silk with locations, Carman (2800 CHU) and
Reinland (3000 CHU), the sites with the greater CHU accumulation had the
longer days to silk and as would be predicted the greater grain yield.
The site at Edwin (2450 CHU) produced lower yields and produced silking
in fewer days.
The results of this
study indicate that currently the CHU is a valid system for rating corn
maturity. The problem lies in the CHU ratings that are assigned to corn
hybrids by the developers. These values do not appear to have a valid
scientific basis and are probably only indicative of part of the genetic
material that make up the hybrid.
Enhanced Weed Management
All herbicide treatments gave
good weed control and had no negative effect on the crop as crop tolerance
was good. Although there were a few differences in grain yield among
treatments, grain yield was more variable in 2001 than in 2002. These
results are not surprising since these tank mixes are registered and
commonly used in Ontario and the northern states of the U.S. These
mixes will be of benefit to Manitoba corn producers and we will be
applying to the Pest Management Regulatory Agency for minor use
registration for Manitoba.
Acknowledgement:
This
project was made possible due to funding from the Governments of
Manitoba and Canada through the Canada-Manitoba Agri-Food Research and
Development Initiative (ARDI).
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