The Changing Face Of
Manitoba Crop Rotations
Doug Wilcox,
Manager, Program Development - Insurance
Manitoba Agricultural Services Corporation
Presentation to the Manitoba Agronomists Conference
U of M, Winnipeg, Dec 12, 2012
The problem

In recent years more and more Manitoba
producers are increasingly willing to face
the additional risk resulting from shorter
than recommended crop rotation break
periods with the objective of improved
short-term revenue potential.
Changing Face….

The extent and impact of this “changing
face” of crop rotation on several major
annual spring crops grown in Manitoba
has been quantified over the years using
annual crop acreage and yield records
reported by AgriInsurance clients to
MASC
Data Analyzed…

MASC has been collecting client
information for decades and the acreage
of crops insured by MASC in most years
is over 85 per cent of all annual crop
acres grown in Manitoba, making the
database very representative and useful.
Data Analyzed


All summary results are based on MASC
database field histories from fields 120
acres or larger tracked over the relevant
periods.
Analysis is limited to larger fields as
MASC does not track field positions
within quarter sections.
Some Historical Analysis…
16%+

MASC wheat
yield data,
1982-93
8%+
11%+
Bourgeois, L. and Entz, M. H. 1996. Influence of previous crop type on yield of spring wheat:
Analysis of commercial field data. Can. J. plant sci. 76: 457459.
Observations…


Rotational benefits recorded in small plot
trials are also observed in commercial
crop production.
Results should encourage producers to
grow spring wheat in sequence with noncereal crops.
Some Historical Analysis…


Wheat yield
deviation
1997-2006
Avg 24
bu/ac diff
between
best & worst
stubble yield
D. Wilcox. 2008. Rotation still has a big influence on yield. Grainews March 10, 2008 pg 6-7.
Some Historical Analysis…


Canola yield
deviation
1997-2006
10 bu/ac
diff between
best & worst
stubble yield
D. Wilcox. 2008. Rotation still has a big influence on yield. Grainews March 10, 2008 pg 6-7.
Observations…

For both wheat and canola, the same
four types of stubble at planting resulted
in the highest average yields:



White pea beans, Potatoes, Fababeans, Grain
corn
Cause not determined – high residual
fertility?
Fall rye stubble resulted in lowest yields.
Observations…

Wheat on wheat



Canola on canola



Average yield 90% of average.
Wheat on cereals – generally below avg ylds
Average yield 93% of average.
Canola on broadleaved crops – generally
below average yields
Below average yields when planted on
alfalfa hay stubble and fallow fields

Alfalfa allelopathy? Fallow lower fertility?
Some Stubble Analysis…Fields
A. Kubinec 2009. Canola on canola – your fields say it doesn’t work. Yield Manitoba, Feb 2009, pgs 22-23 &
D. Wilcox 2000. Manitoba Crop Rotation Information. Yield Manitoba, Feb 2000, pg 14
Main stubble @ planting…








Canola – Sp Wheat (53%)
Sp Wheat – Canola (58 %)
Soybean – Sp Wheat (25%), Oat (17%), Canola (10%)
G Corn – G Corn (13%), Wheat (12%), Canola (11%)
Navy Bean – Sp Wheat (44%), Canola (16%)
Field Pea – Sp Wheat (59%)
Flax – Sp Wheat (54%)
Barley – Canola (35%), Sp Wheat (23%)
Cereals – less crop on crop

Crop – 1994-98 vs 1998-07

Sp wheat – 30% vs 11%
Barley – 15% vs 10%
Oat – 9% vs 4%

Canola – 2% vs 3%

Other crops – not done in 98 or NSD


Some Stubble Analysis…Yields
A. Kubinec 2009. Canola on canola – your fields say it doesn’t work. Yield Manitoba, Feb 2009, pgs 22-23 &
D. Wilcox 2000. Manitoba Crop Rotation Information. Yield Manitoba, Feb 2000, pg 14
Best Crop on Crop Yields…
Observation…


Canola on Canola yield decline…
Crop – 1994-98 vs 1998-07

Canola – 88% vs 82%

Cereal crops – not much change
Note…


These are average observations…not
recommendations
Similar observations are more likely to be
obtained in a particular farm operation if


Significant yield difference &
High frequency of farmers reporting result
Recently took analysis of
observations to next level

Moved from stubble (one year) to break
period analysis (0, 1yr, …. 4+yrs)
Recent Analysis…

Average %
acres by
break period
for major
crops 20002010
D. Wilcox 2012. The crop rotation break interval effect in Manitoba. Yield Manitoba, Feb 2012, pgs 10-13.
“Good” Break Periods…

Greater
than 50% of
fields with 4
or more
years
between
plantings
“Tight” Break Periods…


Red Greater
than 10% of
fields with 0
years
Green –
Approx ½
acres with
<=1 year
Recent Analysis…

Average %
Yield
deviation by
break period
for major
crops 20002010
D. Wilcox 2012. The crop rotation break interval effect in Manitoba. Yield Manitoba, Feb 2012, pgs 10-13.
“Textbook” Responses…

4-0 Yield
Diff



Flax – 6
bu/ac
Field Peas
– 8 bu/ac
Oats – 18
bu/ac
“Almost Textbook”
Responses…

3-0 Yld Diff




Barley – 9
bu/ac
Grain Corn
– 19 bu/ac
Canola – 5
bu/ac
RS Wheat –
6 bu/ac
Cause of 4th Year decline…


Natural data variability (statistical
significance not determined) or
confounding unidentified variables
(management, regions, weather)
Perhaps – if choosing to grow these
crops less frequently these producers
have less experience/less interest in
these crops and in turn are less
successful?
“Asymetric” Responses…


Non-oil
sunflowers
& soybeans
“bounceall-over”
Perhaps
b/c limited
data (sunf)
and limited
experience
(soy)
Recent Analysis

Note that
even
textbook
crops can
be nontextbook in
some
years..

Flax 2004
D. Wilcox 2012. The crop rotation break interval effect in Manitoba. Yield Manitoba, Feb 2012, pgs 10-13.
Canola…


Lots of
recent
interest in
canola
rotations…
Certainly
tight
rotations are
increasing
Effect of Crop Rest Periods on Canola Yield
1.2
0
1
2
3
4
1
Yield (tonnes/ac)
0.8
0.6
0.4
0.2
0
2000
2001
2002
2003
2004
2005
2006
Year
2007
2008
2009
2010
2011
2012
Other crops are also at risk…
MASC "No-Break" Rotation
Summary (2000-2010)
DESCRIPTION
% Field #
% Of Avg Yield
GRAIN CORN
13.2%
89%
RED SPRING WHEAT
11.6%
90%
SOYBEANS
11.6%
97%
BARLEY
11.3%
88%
OATS
4.7%
85%
CANOLA
3.8%
87%
FLAX
0.4%
80%
NON-OIL SUNFLOWERS
0.2%
101%
FIELD PEAS
0.1%
88%
MASC Data "No-Break"
Rotation Summary (2011)
DESCRIPTION
GRAIN CORN
RED SPRING WHEAT
SOYBEANS
BARLEY
OATS
CANOLA
FLAX
NON-OIL SUNFLOWERS
FIELD PEAS
% Field #
% Of Avg Yield
5.7%
87%
2.1%
79%
16.0%
94%
6.0%
85%
9.3%
76%
13.0%
88%
0.8%
112%
N/A
N/A
N/A
N/A
Crop Insurance….


MASC has the authority to deny coverage
for improper rotations under the
contract:
5.01 Uninsured Causes. This Contract
does not insure against any loss or
damage, resulting from one or more of
the following: ….(j) improper crop
rotation,…
Crop Insurance…

Regardless of the cause, MASC has
insurance mechanisms to incorporate the
negative crop production experience of
producers when they have lower than
average yield potential (e.g. IPI system)
and/or higher losses than normal (e.g.
Discount/Surcharge system).
Summary comments…


MASC client records confirm that for
many crops there is a positive yield
response associated with increasing crop
rotation break intervals in commercial
fields.
MASC client records also demonstrate
that in the real world the positive crop
rotation yield response is not always
“text-book” and can vary by crop, break
interval, and year.
The challenge…

The challenge faced by those making
field rotation decisions is to use MASC
observations and other extension
information to continually re-determine
the 'best' crop rotation for each field
according to individual problems,
circumstances and commodity prices.
Thank-You …
[email protected]