European Journal of Agronomy 12 2000 103–115 www.elsevier.comlocateeja
Intercropping corn with soybean, lupin and forages: yield component responses
K. Carruthers, B. Prithiviraj, Q. Fe, D. Cloutier, R.C. Martin, D.L. Smith
Department of Plant Science, Macdonald Campus, McGill University, 21, 111 Lakeshore, Ste. Anne-de-Bellevue, Que., Canada Accepted 20 September 1999
Abstract
Intercropping systems influence yield variables of the component crops, such as harvest index, hundred seed weight, number of reproductive organs and number of seeds, within each reproductive unit. Two experiments were carried
out at each of two sites during 1993 and 1994. The first experiment investigated the effects of seeding soybean or lupin alone or in combination with one of three forages annual ryegrass, Lolium multiflorum Lam.; perennial ryegrass,
Lolium perenne L.; red clover, Trifolium pratense L. with corn on the yield components of corn, soybean and lupin. The second experiment examined the effects of seeding date simultaneous with corn or 3 weeks later and number of
rows of large seeded legumes one or two seeded between the corn rows. Corn grain yield was generally not affected by any intercrop treatment, although in 1993 some simultaneously seeded treatments resulted in decreased yields.
Soybean grain yield was decreased by most treatments, although some simultaneous seedings produced yields similar to soybean monocrops. Lupin grew poorly as an intercrop component, producing little or no grain. Corn harvest
index was not affected by any intercrop treatments. Seeding corn and large-seeded legumes simultaneously resulted in decreases in corn hundred seed weights by as much as 6.6 g compared with the monocropped corn. In 1993 a year
with normal precipitation levels, the hundred seed weight and number of seeds per soybean pod were decreased by intercropping, although the harvest index was not affected. In a high precipitation year 1994, the soybean harvest
index was decreased by intercropping, but not the seed components. The underseeded forages, annual ryegrass, perennial ryegrass and red clover, had no effect on yields or yield components of the other intercropped species.
© 2000 Elsevier Science B.V. All rights reserved.
Keywords: Corn; Forages; Intercropping; Silage; Soybean; Yield components
1. Introduction nations of certain crops result in increased compe-
tition among the components. This results in Intercropping is used in many parts of the world
reduced yields, which may make some crop species for the production of food and feed crops. In
unsuitable for intercropping. Increased competi- general, intercropping has been shown to be more
tion may be for water, nutrients, light or any productive than monocropping. However, combi-
combination of the three, ultimately leading to changes in crop productivity levels. Changes in
crop development can be examined by investigat-
Corresponding author. Tel.: +1-514-398-7851;
ing the manner in which yield components are
fax: +1-514-398-7897. E-mail address: dsmithagradm.lan.mcgill.ca D.L. Smith
affected by alterations in cropping pattern. For
1161-030100 - see front matter © 2000 Elsevier Science B.V. All rights reserved. PII: S 1 1 6 1 -0 3 0 1 9 9 0 0 05 1 - 9
104 K. Carruthers et al. European Journal of Agronomy 12 2000 103–115
example, the harvest index HI indicates the
2. Materials and methods
amount of plant biomass allocated to grain, thus 2.1. Experiment 1
providing an indication of the ability with which the plant partitions resources between vegetative
This experiment investigated the effects of inter- and reproductive structures Fukai and Trenbath,
cropping silage corn with large-seeded legumes 1993. The hundred seed weight HSW gives an
and forage crops on silage yield and quality. This indication of the ability of the plant to meet sink
field study was carried out in 1993 and 1994 at the demands during grain filling and can be increased
E. Lods Agronomy Research Centre, on the by the removal of various stresses, e.g. irrigation
Macdonald Campus
of McGill
University where water is limiting Claassen and Shaw, 1970;
Macdonald , and the L’Assomption field station Putnam et al. 1992.
of Agriculture
and Agri-Foods
Canada Intercrop systems may improve yield stability,
L’Assomption. The two sites are 80 km apart. allowing more consistent yields Willey, 1979;
The Macdonald experiment was performed on Horwith, 1985; Fukai and Trenbath, 1993, and
soils consisting of a mixture of Chateauguay clay efficient use of the resources, allowing reductions
fine loamy, mixed, nonacid, frigid, Gapludalf in costly inputs Keatings and Carberry, 1993;
1993 and St. Bernard clay fine loamy, mixed, Morris and Garrity, 1993ab.
nonacid, frigid, Eutrochrept 1994, whereas the Cereal–legume intercrops are among the most
L’Assomption study was performed on a Soulange frequently used and most productive Ofori and
loam fine
silty, mixed,
nonacid, frigid,
Stern, 1987a. Corn–soybean intercrops have been Humaquept. Prior to experimentation, soil tests
shown to be more productive than corn monocrops showed a pH of 6.6 for the L’Assomption site and
Ahmed and Rao, 1982; Putnam et al., 1985; 5.1 for the Macdonald site. Agricultural limestone
Marchiol et al., 1992. The soybean component at 6 t ha−1 was applied to raise the pH at the
adds valuable nitrogen to the soil Singh et al., Macdonald site. The soil was harrowed 7 days
1986, and improves overall protein content of the before
planting, after
which lime
and resulting silage Herbert et al., 1984; Martin et al.,
90 kg ha−1, 100 kg ha−1, and 140 kg ha−1 of N, P 1990. Further, this intercrop system reduces weed
and K respectively were broadcast and disked in growth Tripathi and Singh, 1983; Weil and
to produce a smooth seed bed. Corn monocrop McFadden, 1991; Carruthers et al., 1998, allowing
plots received an extra 90 kg ha−1 of nitrogen, reductions in herbicide use. Several reports on
hand broadcast 2 weeks after corn seeding, to give corn–soybean intercrops exist in the literature.
a total of 180 kg ha−1 in each of these plots However, other potential cereal–legume intercrop-
Martin et al., 1990. In 1992 the Macdonald site ping systems, such as corn–lupin, have not been
was fallow and the L’Assomption site was pasture. studied in detail. Further, there are very few
The experiment was established in a randomized reports
on corn
intercropping along
with complete block design with four blocks. Individual
underseeded forages. treatment plots measured 3×7 m
2 Table 1. Corn, Two experiments were carried out to investigate
large-seeded legumes, and forage monocrops were how intercropping corn with soybean or lupin
simultaneously seeded in mid May Table 2. The affected their yield components. The first experi-
corn hybrid was changed in 1994 to one that was ment examined the effect of interseeding one of
slightly shorter in stature to allow better growth the large-seeded legumes alone or in combination
of the other intercrop components. The annual with each of three forages annual ryegrass, Lolium
ryegrass was replaced by a mixture of perennial multiflorum Lam.; perennial ryegrass, Lolium per-
ryegrass and red clover in 1994. Corn was planted enne L.; red clover, Trifolium pratense L.. The
in four rows, 75 cm apart, in each plot with a John second experiment explored the effect of seeding
Deere seeder model Max Emerge2 2700 at the large-seeded legumes simultaneously with corn,
L’Assomption and a Gaspardo seeder SP 510, or 3 weeks after the corn and in one or two rows
Pordenone, Italy at Macdonald. The large-seeded legumes were seeded in eight rows spaced 37.5 cm
between each pair of corn rows.
105 K. Carruthers et al. European Journal of Agronomy 12 2000 103–115
Table 1 Treatments applied in experiment number 1 both 1993 and 1994
Treatment Cropping system
Description Corn
Monocrop Corn — herbicide control
Soybean Monocrop
Soybean-monocrop Lupin
Monocrop Lupin-monocrop
CS Intercrop
Corn+soybean CL
Intercrop Corn+lupin
CAnn mix Intercrop
Corn+annual ryegrass 1993 or mixture 1994 CPer
Intercrop Corn+perennial ryegrass
CRed Intercrop
Corn+red clover CSAnn
Intercrop Corn+soybean+annual ryegrass 1993 or mixture 1994
CSPer Intercrop
Corn+soybean+perennial ryegrass CSRed
Intercrop Corn+soybean+red clover
CLAnn mix Intercrop
Corn+lupin+annual ryegrass 1993 or mixture 1994 CLPer
Intercrop Corn+lupin+perennial ryegrass
CLRed Intercrop
Corn+lupin+red clover CWeed
Monocrop Corn — unweeded control
CHand Monocrop
Corn — hand-weeded control Table 2
Crop varieties and seeding densities for both experiments in 1993 and 1994 Crop
Cultivar Population
Monocrop Intercrop
Corn Zea mays L. Pioneer 3921 1993
80 000 plants ha−1 80 000 plants ha−1
Pioneer 3917 1994 80 000 plants ha−1
80 000 plants ha−1 Soybean Glycine max L.
Maple Glen 250 000 plants ha−1
Lupin Lupinus albus L. Amiga
250 000 plants ha−1 Annual ryegrass Lolium multiflorum Lam.
Marshall 1993 10 kg ha−1
Perennial ryegrass Lolium perenne L. Linn
13 kg ha−1 Red clover Trifolium pratense L.
Khunn 25 kg ha−1
Mixture of perennial ryegrass and red clover Linn and Khunn 6 kg ha−1+15 kg ha−1
apart in monoculture plots. In intercrop plots one Prior
to seeding
the large-seeded
legume monocrops in 1994 each plot received Dual
row of large-seeded legumes was seeded between each corn row, using a Planet Jr hand seeder
Metolachlor and
Lorox Linuron
[3-3, 4-dichlorophenyl -1-methoxy,1-methylurea]
at model 300A, Allen and Company, Philadelphia,
USA. All legumes soybean, lupin and red clover 2 l ha−1 and 2.1 l ha−1 respectively applied with
a bicycle-wheel plot sprayer. After two cultiva- were inoculated with their appropriate Brady
Rhizobium strains using commercial inoculants tions using a Rabewerk cultivator Rabewerk
Machinerie Agricole, St.-Cesaire, Canada 1993 or Lipha Tech, Wisconsin, USA prior to seeding.
Prior to seeding in 1993 and 1994, the corn mono- a rotary hoe cultivator Colpron, Montreal, Canada
1994 and 3 weeks after corn seeding, intercropped crop received a combination of Dual Metolachlor
[2-chloro-N-2-ethyl-6-methylphenyl -N-2-methoxy- forages were hand broadcast throughout the plots.
Forages were included to provide improved weed 1-methylethyl acetamide] and atrazine [6-chloro-
N-ethyl-N∞-1-methylethyl-1,3,5-triazine-2,4-dia- control and contribute organic matter to the soil.
Average monthly rainfalls and temperatures for each mine] at a rate of 1.9 l ha−1 and 1.0 l ha−1 respec-
tively applied with a bicycle and wheel plot sprayer. site-year are given in Table 3.
106 K. Carruthers et al. European Journal of Agronomy 12 2000 103–115
Table 3 Monthly precipitation and average temperatures recorded at the Macdonald and L’Assomption sites during the 1993 and 1994
growing seasons Year
Precipitation mm Temperature °C
May June
July August
September Total
May June
July August
September Macdonald
1993 79.1
74.8 94.6
57.2 119.2
424.9 13.3
17.6 21.4
20.5 13.9
1994 148
194 61.3
99.9 105.5
607.8 12.1
18.9 21.3
18 14.3
Average a
70.6 88.3
89.7 92.6
97.9 439.1
13.1 18.1
21.1 19.8
14.7 L’Assomption
1993 95.6
74.2 75.4
95.6 89.1
429.9 12.7
17.4 20.7
20.3 13.6
1994 93.8
285.9 b
122.8 67.8
121.6 691.9
11.8 19.3
21 19.2
14.7 Average
a 72.5
87 84.5
94.4 84.6
423 12.3
17.5 20.2
18.8 13.8
a 30 year averages. b Flooding occurred.
During the season, plant heights were measured determine pod number per plant and seed number
per pod. These values were averaged to provide at approximately 2 week intervals for the corn and
legume species. In October, hand harvesting of yield values on a per plot basis. All grain was
weighed in 100 seed groups to determine the HSW. corn and legumes was done in the middle rows of
the plots in order to avoid border effects. Corn The number of kernels per cob was determined by
dividing grain yield by the average weight per seed was harvested from the middle 2 m 1993 or 3.5 m
1994 of the two centre rows, the legumes from and then dividing by the number of cobs harvested.
Land equivalence ratio LER was calculated the middle 3 m 1993 or 3.5 m 1994 of the
centre two rows in intercrops or centre four rows according to method described by Mead 1986.
in monocrop. Grain was separated using a combine Wintersteiger America Inc., Lincoln, NE USA.
2.2. Experiment 2 Subsamples of the grain component were dried at
80°C for 24 h to determine yield. A total of 15 This experiment investigated the effects of the
number of rows and seeding date of the inter- large-seeded legume plants per plot were used to
Table 4 Treatments applied in experiment number 2 for 1993 and 1994
Treatment Cropping system
Description Corn
Monocrop Corn-herbicide control
Soybean Monocrop
Soybean-monocrop Lupin
Monocrop Lupin-monocrop
CS1S Intercrop
Corn+1 row of soybean simultaneously seeded CS2S
Intercrop Corn+2 rows of soybean simultaneously seeded
CS1D Intercrop
Corn+1 row of soybean delay seeded by 3 weeks CS2D
Intercrop Corn+2 rows of soybean delay seeded by 3 weeks
CL1S Intercrop
Corn+1 row of lupin simultaneously seeded CL2S
Intercrop Corn+2 rows of lupin simultaneously seeded
CL1D Intercrop
Corn+1 row of lupin delay seeded by 3 weeks CL2D
Intercrop Corn+2 rows of lupin delay seeded by 3 weeks
Cweed Monocrop
Corn — unweeded control Chand
Monocrop Corn — hand weeded control
107 K. Carruthers et al. European Journal of Agronomy 12 2000 103–115
cropped large-seeded legumes on silage yield com- using the logx+1 transformation prior to analy-
sis. LER was calculated according to method ponents. Seedbed preparation and seeding were
the same as for the previous experiment. The described by Mead 1986.
treatments applied in the experiment are detailed in Table 4. When legumes were seeded in two rows
in intercrop plots an intercrop density of 250 000
3. Results and discussion
