Optimizing Substrate Moisture Measurements In Containerized Nurseries: Insights On Spatial and Temporal Variability

Substrate moisture dynamics were continuously measured in a container grown nursery environment using a system of moisture sensors connected to a wireless data logger network.  We examined spatial and temporal variation in volumetric water content (VWC, m³ • m^-3) among containers in ten tree species. Despite equal irrigation, variation in VWC occurred within (standard deviations averaged 13 - 25% of mean VWC) and among (p <0.05 for 61 of 118 days) species.  Moreover, seasonal differences in within species variation were evident in nine of the ten species. Based on the observed spatial and temporal variation in substrate VWC, we recommend species specific substrate moisture sensor deployment.  We report substrate moisture sensor quantities that adequately estimate the mean substrate VWC of each species population within ± 5% VWC.  Given the economic value of water and its control on biomass production, we conclude that nursery managers can maintain optimal substrate moisture with minimal sensor deployment.