Disclosed are methods of enhancing growth of soybean plants, comprising treating soybean seed or the soybean plant that germinates from the seed with an effective amount of at least one chitooligosaccharide, wherein upon harvesting the soybean plant exhibits at least one of increased plant yield measured in terms of bushels/acre, increased root number, increased root length, increased root mass, increased root volume and increased leaf area, compared to untreated soybean plants or soybean plants harvested from untreated soybean seed.