Heavy (i.e., fine-textured) Soils

Soils having abundant 2:1 clay mineralogy (i.e., smectite and vermiculite), that are susceptible to shrink and swell episodes throughout the growing season, can experience extensive soil shrinkage that may cause separation of the PRS™-probes from the soil, resulting in poor contact between the ion-exchange membrane and soil. If the soil is dry enough to form desiccation cracks, what is the expected plant nutrient uptake under such conditions? However, if these soil physical dynamics cause the PRS™-probes to lose proper contact with the soil, then this obviously is a concern. Depending on the clay mineralogy of your soils and the proximity to the study sites, periodically checking the installation of the PRS™-probes after extended dry cycles is recommended. In extreme cases, it may be necessary to bring soil cores back to the lab where moisture levels can be easily monitored.