Characterizing the seasonal variation of temperature and moisture of containerized crops media

Most of containerized nursery crops are grown in soilless substrates. Pine bark based container substrates, common in the southeastern USA, are characterized by a rapid variation on media moisture and temperature. The objectives of this study were to characterize the seasonal variation of containerized crops' media temperature and moisture in three container sizes and to assess potential relationships among containers' media variables, e.g. temperature and moisture, and between the container and weather variables. An experiment was conducted at Monrovia Growers, Cairo, GA, from October 2004 to September 2007. Temperature and TDR (Trace Domain Reflectometry) moisture probes, connected to an automated data logger, were installed in three container sizes, including 18.9-, 26.5-, and 57.8-L. Black color containers until March 2006 and green thereafter were used. Containers were filled with a mixture of 80% pine bark and 20% compost. A micro irrigation system consisting of stakes was used. Irrigation was triggered once a day during the winter and twice to three times a day during the other seasons. Container conditions were recorded every 15 minutes and daily averages were calculated at midnight. Weather data were obtained from a nearby weather station of the Georgia Automated Environment Monitoring Network (AEMN. The information was retrieved hourly by a computer located at The University of Georgia Griffin Campus. Average daily media temperature and moisture and weather data were used for this study. All data sets were split into subsets consisting of the 2005, 2006, and 2007 seasons. A statistical analysis to determine differences for media temperature and moisture between seasons, pot sizes and color, and their interaction was performed. Significant differences for media temperature and moisture was found between seasons, container sizes, and their interaction. A significant correlation was also found between container media temperature and weather variables, whereas no correlation was found between media moisture and weather variables. Further research should focus on the 15-minute data sets to determine a more accurate association and relationships within and between media and weather variables.