Presentation on theme: "Abstract. A Comparison of Modern and Indigenous Agriculture: Monoculture Versus Polyculture Nanci Ross, Thomas Rosburg, Michael Stein Department of Biology,"— Presentation transcript:
Abstract. A Comparison of Modern and Indigenous Agriculture: Monoculture Versus Polyculture Nanci Ross, Thomas Rosburg, Michael Stein Department of Biology, Drake University, Des Moines, IA Objective Results References and Acknowledgements Methods. Conclusions Introduction/Background 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. 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. 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  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  An ample supply of water causes healthier corn and higher yields  An ample supply of water allows the beans to fix more nitrogen  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  Experimental findings point to higher corn yields using polyculture  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 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 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 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. 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 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. 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. 1. C ̧ akir, 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. 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 MAINTENANCE All pots were given 200 ml of water daily Temperature was kept at a standard 80 o Fahrenheit (27 o Celsius) Grow lights were kept on from 7:00 am to 7:00 pm 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 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 . 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 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.