Biocontainer water requirements

Despite the introduction of different types of biocontainers, limited research has been published regarding specific characteristics of biocontainers compared to traditional plastic containers. One particular area of importance is the amount of water that is needed to produce a commercial crop. Many biocontainers have water permeable walls, which cause the growing substrate to dry faster than in traditional plastic containers.

Research was conducted to determine the amount of water required and the length of time between irrigations to produce a marketable geranium crop. Water loss through the container walls was also determined (Table 1).
 

For the water use study, all containers were filled with a peat-based substrate. Plants were irrigated with 15-5-15 fertilizer at 200 parts per million nitrogen when the substrate surface was dry. At each irrigation, plants were placed on drainage trays, irrigated with 150 milliliters of water and the leachate was collected and measured. Geraniums were grown for eight weeks. Total water use and average irrigation interval are shown in Table 2.
 

The rice hull pot was the only 4-inch biocontainer that did not require more water than plastic containers to produce a marketable geranium. The rice hull pot also had the longest time interval between each irrigation. When the substrate volume was increased in the straw and paper containers, the amount of water required and the irrigation interval increased. These factors were not significantly different between the OP47 and the 5-inch plastic container control.


Measuring water loss
Containers tended to segregate into three groups based on water loss rates through the container walls (Table 3). Plastic, rice hull and OP47 containers had rates of water loss that were close to zero. Straw Pot, cocofiber, Fertil and peat containers had the highest rates of water loss. CowPots and paper containers had water loss rates that were between these two groups.