A Comparison of Modern and Indigenous Agriculture: Monoculture Versus Polyculture
Nanci Ross, Thomas Rosburg, Michael Stein
Department of Biology, Drake University, Des Moines, IA
Abstract
Results
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DATA COLLECTION
Corn height was measured from the soil to the bottom of the top leaf
Corn diameter was measured just above the first set of adventitious roots
Beans were removed from the pod and massed for each treatment
Squash was removed from the stem, and the total fruit for each treatment was massed
 Average bean and squash masses per plant were added together for total food mass
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Average Corn Stalk Height Between Treatments
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5.80
Polyculture
Monoculture
Mass of Beans (g.)
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800
5.60
5.40
400
5.20
200
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0
4.80
Average Number of Male Flowers Per Corn Plant
Figure 3: Average Male Flower Production
The average male flowers produced on each tassel was
calculated for both treatments. The average flower count
for the polyculture treatment was 765.2, while the
average flower count for the monoculture treatment was
992.75. The polyculture treatment had also produced no
female flowers, while the monoculture treatment had 50%
of the plants produce female flowers.
p=0.289
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The results of this experiment were interesting, and often quite mixed. One thing that we
noticed was the stunted development of the corn. By the data collection date of 4/6/2011, over
sixty days had passed in the growing period, yet none of the corn plants in either treatment
produced a complete fruit. Both treatments had average heights of less than 1 meter for both
treatments (figure 1). This is less than half the height that a corn plant should reach. The
stunted development most likely stemmed from the fact that the plants were kept indoors in a
confined space, and relied on mainly artificial light for the beginning of the growth period. In
order to substitute fruit mass, the health of the plants in each treatment was instead measured
through height (figure 1), basal diameter (figure 2), and male flower count (figure 3). Through a
significant difference in the height of the stalks in each treatment, it was found that the
monoculture corn had significantly higher growth rates, most likely due to the heavy fertilizer
application at the beginning of the growing season.
When the beans were measured, they were placed into separate groupings based solely
on treatment, giving us only an average number and making it so that we could not run
statistical tests on the crop. However, when looking at the average mass production (figure 4), it
was noted that the monoculture bean treatment showed a pattern of producing more beans, in
both mass and number per plant, than the polyculture treatment. This result was supported by
similar findings in agricultural tests [5]. The drop in bean production may point to a visible
consequence of competition between the beans and the squash in the pots.
The squash findings were the opposite of the bean findings. While the squash was
separated into its treatments, it was possible to mass each fruit. A t-test showed that there was
no statistical difference between the masses of the fruits in either treatment. However, when the
mass was averaged per plant, it was found that the squash plants grown in polyculture
produced almost twice the amount of fruit on average that the plants in the monoculture
treatment produced (figure 5). This great advantage by the polyculture plants could point to a
benefit from the nitrogen produced by the beans, and a benefit from the loss of competition by a
second squash plant.
With the large difference between the masses of squash production well overcoming the
small difference between the masses of bean production, it was seen that the polyculture
treatment produced almost twice the total food per pot on average than the monoculture
treatment produced. While there is no way to run a statistical test, as this was a calculation
based on average values, there is a definite trend towards this conclusion.
Future Research
Average Mass of Beans Produced Per Plant in
Polyculture and Monoculture
To improve this study in the future, the primary goal would be to use an outdoor setting.
This would remove negative effects of competition, and would give the plants access to more
natural water and light cycles. This would hopefully produce healthier plants and more natural
crop production and results.
To run this study more effectively, all crop products should remain separated not only by
pot, but by plant as well. This would remove the need to run averages for the treatments, and
would allow the use of statistical tests to find real differences.
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40
Weight (g)
Polyculture
Monoculture
Figure 4: Average Bean Production
The average bean production (wet mass) per plant was
calculated for both treatments. The average production for
the polyculture treatment was 14.74 beans and 5.32g
produced per plant. The average production for the
monoculture treatment was 18.44 beans and 6.04g
produced per plant.
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Average Corn Basal Diameter Between Treatments
Figure 2: Average Corn Basal Diameter
The average basal diameter for the corn stalk was
measured for both treatments. The average diameter for
the polyculture treatment was 13.99 mm, while the
average diameter for the monoculture treatment was
14.67 mm. p=0.331
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Polyculture
Monoculture
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6.20
Polyculture
Monoculture
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MAINTENANCE
All pots were given 200 ml of water daily
Temperature was kept at a standard 80o Fahrenheit (27o Celsius)
Grow lights were kept on from 7:00 am to 7:00 pm
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Methods.
SETUP
The experimental setup consisted of 36 one gallon pots filled with a 60/40 mix of organic
potting soil and top soil.
Nine pots were dedicated to bean and squash polycultures
Nine pots were dedicated to bean monocultures
Nine pots were dedicated to squash monocultures
Four pots were dedicated to corn monocultures
To simulate modern monoculture, the plants were given heavy doses of fertilizer
Five pots were dedicated to corn, beans, and squash polycultures
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11.50
Production (g)
Polyculture was a very common agricultural system throughout the Americas
Regional varieties occurred over the US and Mesoamerica [3,4,5,6]
Northeastern “Three Sisters” polyculture is one of the most documented methods [4]
Contains a mixture of corn, beans, and squash [4,5]
Corn (Zea mays) was a major food crop and gives the beans a climbing pole [4,5]
Beans (Phaseolus vulgaris) are high in amino acids that compliment the corn, and contain
nodules for nitrogen fixation [4,5]
Squash (Cucurbita sp.) was high in proteins and energy and creates a living mulch to
keep the soil moist, shades out weeds, and offers protection against pests [4]
•An ample supply of water causes healthier corn and higher yields [1]
•An ample supply of water allows the beans to fix more nitrogen [2]
Experimental and historical evidence point to large yields with this method [4,5]
English and French colonists wrote about the enormous yields of the Iroquois people [4]
Experimental findings point to higher corn yields using polyculture [5]
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Figure 1: Average Corn Stalk Height
The average height for the corn stalk for both treatments
was measured. The average height for the polyculture
treatment was 81.79 cm, while the average height for the
monoculture treatment was 94.08 cm. p=0.043
Number of Male Flwers
Introduction/Background
Polyculture
Monoculture
Average Basal Diameter (mm)
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Objective
The objective of this experiment was to find out if a series of corn, beans, and
squash monocultures or a “Three Sisters” style polyculture method produced a
higher average total food mass.
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Average Stalk Height (cm)
Although monoculture cornfield is the standard method of farming for modern
agriculture, polyculture was a dominant system for indigenous cultures in the
New World. These systems were discussed widely in the personal writings of
missionaries and settlers, who marveled at the agricultural productivity of the
native people. The Three Sisters method, consisting of a close grouping of corn
(Zea mays), beans (Phaseolus vulgaris), and squash (Cucurbita sp.), was one
of the most common polyculture methods throughout North America. The
method is admired, as it produces a complete diet, and the mutualistic
relationships between the plants encourage higher yields. The purpose of this
experiment was to test for a difference in crop productivity and yield between a
corn monoculture and the Three Sisters setup. In this greenhouse study, pots
were planted with only corn and were treated at the beginning of the growing
season with synthetic fertilizer representing modern monoculture. This
treatment was compared with pots planted with corn, pole beans, and butternut
squash, a variation of the Three Sisters. To test productivity, the sizes and
flowering times of the corn were measured. The yield and weights of all fruits
produced by the plants was also collected. The monoculture treatment showed
trends of faster development in height and flowering times. However, the
polyculture method has the possibility to deliver higher combined yields and
produce more total food.
Conclusions
References and Acknowledgements
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Polyculture
Monoculture
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We would like to thank Drake University for allowing us extended use of the greenhouse space. We want
to acknowledge Dr. Keith Summerville for his advice and for supplying the digital calipers used in this
experiment.
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Average Squash Production Per Plant Between
Polyculture and Monoculture
Figure 5: Average Squash Production
The average squash production (wet mass) per plant was
calculated for both treatments. The average production
for the polyculture treatment was 0.55 fruits and 53.58g.
The average production for the monoculture treatment
was 0.22 fruits and 24.84g.
p=0.274
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Average Food Production Per Pot Between
Monoculture and Polyculture
Figure 6: Average Total Food Production
The total average food production (wet mass) per plot
was calculated for both treatments. The average
production for the polyculture treatment was 58.90g.
The average production for the monoculture treatment
was 30.88g.
1. Çakir, R. (2004). Effect of water stress at different development stages on vegetative and reproductive growth of corn. Field
Crops Research, 89: 1-16.
2. De Costa, W. A. J. M., Becher, M., & Schubert, S. (1997). Effects of water stress on nitrogen fixation of common bean
(phaseolus vulgaris L.). Journal of the National Science Council of Sri Lanka, 25: 83-94.
3. Hemenway, Toby. Gaia's Garden: A Guide to Home-Scale Permaculture. 2nd. White River Junction, VT: Chelsea Green
Publishing Company, 2009. Print.
4. Lewandowski, S. (1987). Diohe'ko, the three sisters in Seneca life: Implications for a native agriculture in the Finger
Lakes region of New York State. Agriculture and Human Values, 4: 76-93.
5. Mt.Pleasant, J., & Burt, R. F. (2010). Estimating productivity of traditional Iroquoian cropping systems from field experiments
and historical literature. Journal of Ethnobiology, 30: 52-79.
6. Tomcek, L. (2010) Heath Site (39LN15): Faunal and Floral Analysis of a Great Oasis Site. UW-L Journal of
Undergraduate Research, 13: 1-21
7. Yadegari, M., Asadi Rahmani, H., Noormohammadi, G., & Ayneband, A. (2010). Plant growth promoting Rhizobacteria
increase growth, yield and nitrogen fixation in Phaseolus vulgaris. Journal of Plant Nutrition, 33: 1733-1743.