ABSTRACT
The study of rhizosphere dynamics involves many disciplines, each requiring specialized research procedures. This chapter discusses the procedures used in quantifying the total amount of roots and their distribution in the growing medium. Microbes thrive in the nutrient-rich rhizosphere, using organic material exuded by the root as an energy source. Some microbes release nutrients and growth-regulating compounds used by the plant. The root environment changes as the rhizosphere is dried and depleted of nutrients through each day by plant extraction and is then re-wetted during the night by redistribution when transpiration is minimal. As root systems extract water from the soil, a water potential gradient develops around the root. The procedures for collecting the samples range from auguring with hand-operated tools to collecting intact cores with hydraulically operated equipment. Increasing labor costs have made excavation techniques uneconomical and have provided the incentive for developing the non-destructive tools.
