Characterizing Biomass Accumulation and Nutrient Uptake In Situ over Time in Wisconsin Peppermint and Spearmint

Mint is a perennial crop in Wisconsin, which historically survives at least 5 to 8 years per rotation.  However, many Wisconsin mint oil producers are currently finding it difficult to keep a healthy stand for more than 3 years.  This is especially true of Scotch spearmint.  Although many factors contribute to this change, our research focus was to observe plant growth in a holistic manner since there is little understanding as to how the plant grows vegetatively and reproductively.  Our experiment collected data on biomass accumulation and major nutrient uptake in above ground (stems and leaves combined) and below ground portions of the mint plant (stolons).  Because stolons are characterized as the reproductive, overwintering portion of the plant, healthy and unhealthy stolons were separated for evaluation to determine potential overwintering effects and nutrient uptake.  The experiment was performed on both mineral and muck soils, on peppermint and Scotch spearmint.  Results included a clear shift in nutrient uptake over time between the vegetative and reproductive parts of the plant as compared between repeated procedures and soil types.