Concept maps are a useful tool for evaluating student understanding of complex subject matter in the disciplines of agriculture science.  It is possible to measure student comprehension by comparing concept map scores before and after teaching the material.  Additionally, by comparing student comprehension with demographic information relevant to the subject matter, it is possible to weight comprehension based on previous knowledge and experience.  Therefore, the purpose of this study was to evaluate the effect of previous knowledge on learning techniques in two agronomy courses: AGRY 105 – Crop Production and AGRY 565 – Soil Classification, Genesis, and Survey.  More than 80 students from a total of three classes constructed pre and post-concept maps.  Students were given 20 minutes to complete a concept map before and after learning the course material.  Concept maps were scored based on valid relationships, hierarchical structure, interconnections, and use of examples for basic soil science. Concept map scores were correlated to student demographics and previous experiences related to soils.  There were visual trends across comprehension and learning experiences.  Concept maps could be a useful tool for measuring and visually displaying student comprehension of complex subject matter.