Preliminary Investigation of Strip Intercropping Corn among Other
Crops in Manitoba – Quantifying the Edge Effect
C. Cavers
Discussion
Background
Strip farming, or contour farming, is a concept that has been practiced in
hilly areas to minimize soil erosion using crops with varying amounts of
residue production.
Prior to corn harvest, observation data indicated that up to 50% bird damage and
wind damage had occurred on the outside rows. If these losses could be
prevented, then a significant positive edge effect for corn yield in Manitoba is
possible. The challenge is to determine how to capitalize on this opportunity with
precision agriculture technology and agronomic principles.
LSD 0.05
Corn Yield (bu/ac)
Intercropping is the practice of producing multiple crops in a given
space, based on the assumption that competition for resources between
species is less than exists within the same species.
Unlike a true intercropping scenario, where two different crops are
planted in the same field at the same time, strip intercropping with two or
more crops (such as corn and soybeans) is done with alternating crop
strips with the intent to capitalize on the premise that outside corn rows
capture more sunlight if more plants are exposed to an open edge like
that found at the corn-soybean border (Van Dee, 2004).
This practice has been conducted in Minnesota, Illinois and Iowa and
other states with varying degrees of success, particularly under
moisture-limiting conditions. Research compiled by Ghaffarzadeh
(1999) suggests the positive effect occurs mainly at the rows at the crop
strip border, though it may extend into the second outside rows; yield in
the centre of strips wider than four rows is equivalent to sole-cropped
corn. They also suggest that strip intercropping benefits are maximized
when the strips run north-south rather than east-west. Negative impacts
to yields of soybeans and other crops adjacent to corn strips (due to
shading, water competition and nutrient depletion) must be offset by
increases in corn yields for the concept to be appealing.
Earlier research by West and Griffith (1992) in Illinois compared “regular” vs
“high input” management in an attempt to take advantage of the positive edge
effect by increasing corn populations in the two outside rows and adding an extra
60 lb/ac between the two most outside rows, resulting in an additional 20 bu/ac
yield under high input management.
Winsor (2011) explored options Iowa producers were examining to capitalize on
the edge effect, such as varying corn hybrids and other crop varieties, using
controlled traffic to reduce soil compaction and utilizing RTK guidance and
planter technology to automate the planting of strip intercropped fields.
1
Figure 2. Corn yield by row position (LSD = 18.1 bu/ac1 @ 0.05)
1
Although this study did not have enough replication to distinguish between corn
yield differences due to row orientation, most of the literature recommends corn
planted in a north-south orientation, with the east outside row (aka Row 8)
benefiting the most from additional sunlight capture.
1
1
Corn yield (bu/ac)
NS
Based on this previous work in other areas, the concept of strip
intercropping may be of interest to Prairie producers who may be
considered early adopters of corn production in their area with smaller
row crop equipment (4-12 rows wide) and access to Real-Time
Kinematic differential correction (RTK) guidance.
Likewise, with no significant differences between corn yields and the adjacent
crop, this study does not indicate any agronomic advantage in the crop to plant
adjacent to corn strips. The literature often defaults to soybeans because of their
prevalence in US crop rotations, being suited for row crop production systems
with corn, and having a growth pattern that does not compete with corn.
NS
Summary
The objectives of this study are to quantify the edge effect on corn as
measured by row position, adjacent crop type and corn row orientation.
14-fallow
Corn hybrids more resistant to bird and wind damage should be tested to find
optimum plant populations to capitalize on the edge effect.
N
15-fallow
16-corn
17-fallow
18-corn
19-soybean
20-corn
10 m
15 m
21-corn
22-canola
23-corn
24-canola
25-corn
26-soybean
10 m
Figure 1. Plot layout at AAFC – Portage, 2015.
Using the plot design layout in Figure 1, a John Deere planter (30–inch
rows) was set to plant 26,000 seeds/ac for corn and 215,000 seeds/ac
for soybeans on June 1, 2015. Canola was planted on 6-inch rows
using a double disk press drill and a seeding rate of 7 lb/ac. The study
area was fertilized May 25 @ 90-60-10-10 (actual) according to soil test
recommendations. All crops in the study were Roundup Ready®
varieties: corn = P7535R; soybean = LS Northwester; canola = SY4135.
Plots were managed for weed growth uniformly using Roundup
Transorb® (glyphosate) applied @ 0.67 L/ac on June 24. Fallow areas
were tilled bare as needed. Plots were harvested on Sept 9 (canola),
Oct 22 (soybean) and Nov. 9 (corn).
Although yields for canola and soybean were not reported, these should be
analyzed to ensure negative effects from corn on these crops are minimized.
NS
NS
NS
Corn Yield (bu/ac)
13-corn
12-soybean
11-canola
10-soybean
9-canola
8-corn
7-canola
6-soybean
5-corn
4-soybean
3-canola
2-corn
1-fallow
10 m
6m
= 8 rows @ 30 inch spacing (corn and soybeans)
= 20 ft with press drill @ 6 inch spacing (canola)
Figure 3. Corn yield by row orientation (non-significant)
Future work on this topic in Manitoba requires more replication for more
rigorous statistical analyses – to measure real differences in corn yield among
individual rows, corn row orientation, and the effect of crop type adjacent to
corn. An economic analysis of strip intercropping effects is also required.
Acknowledgements
Statistical analysis conducted by Craig Linde, MAFRD.
References
Figure 11.
Figure 4. Corn yield by adjacent crop (non-significant @ 5% level)
Ghaffarzadeh, M. 1999. Strip Intercropping. Iowa State University Extension
Pm 1763, Ames. (http://www.extension.iastate.edu/publications/pm1763.pdf).
Van Dee, K. 2004. Corn Yield Effects in a Corn-Soybean Strip Cropping System.
ISRF04-34.
West, T. D. and Griffith, D. R. 1992. Effect of strip intercropping corn and
soybean on yield and profit. J. Prod. Agric. 5:107-110.
Winsor, S. 2011. Farming on the edge. Corn and Soybean Digest. Nov. p. 6-8.