An Evaluation of the Productivity of the Native American 'Three Sisters' Agriculture System in Northern Wisconsin

Abstract

Traditional agriculture systems were once common practice among Native Americans, who produced crops without the addition of synthetic fertilizers and pesticides. Incorporation of Native American cropping practices may be an effective strategy in the development of modern sustainable and organic gardens. Reintroduction of these garden systems into Native American communities may also help increase nutrition and preserve cultural traditions. The Three Sisters garden combines corn, beans and squash, three vegetables that appear to symbiotically benefit each other, thus reducing the need for fertilizers, herbicides, pesticides, irrigation and weeding. Although there are several accounts of the benefits of the Three Sisters approach in popular gardening literature, no scientific studies documenting the effectiveness of the system were found in published, peer-reviewed literature at the time of this study. Through meetings and discussions with members of the Bad River and Red Cliff tribal communities of Lake Superior Ojibwe in Northern Wisconsin held during the summer and fall of 2005, the interests and needs of the these communities were assessed. During this time, the communities expressed a desire to implement sustainable agricultural systems, particularly reinstatement of the Three Sisters. Before promoting the system, however, there was a need to further investigate its potential productivity. This study took place at the Northern Great Lakes Visitor Center and at the Bad River community gardens in Ashland County, WI during the 2006-cropping season. The Three Sisters system was compared to monoculture plantations of corn, bean and squash in terms of soil temperatures, gravimetric soil moisture content, weed cover, pest and disease damage, adverse weather damage and crop yields (yield per plant and calories per acre). The heirloom crops used were analyzed for nutritional data and compared to conventional varieties. Soil samples were collected from each plot before planting and again the following spring, and changes in total soil nitrogen levels were determined. Benefits of the Three Sisters system included increased soil drainage, a reduction in raccoon damage, and a higher yield in calories per acre. Increased soil temperatures in early stages of crop development and decreased soil temperatures in later stages of growth were also observed in Three Sisters treatments. Weed cover in Three Sisters treatments was lower than in monoculture corn and bean treatments, but this difference was only significant for monoculture beans at the Bad River site. More damage to corn plants resulting from adverse weather was observed in monoculture treatments than in Three Sisters treatments; however this difference was not statistically significant. The heirloom crops used (rattlesnake pole bean and Hopi orange squash) were higher in certain nutrients than conventional varieties. No significant difference in the number of cucumber beetles on squash plants and damage caused by corn smut and corn earworm on corn plants was noted between monoculture and Three Sisters treatments. Yield per plant was not significantly greater in Three Sisters treatments than in monoculture treatments. There was also no significant difference in changes in total soil nitrogen between treatments from 2006-2007.