FACTORS AFFECTING THE SWELLING CAPACITY OF PEAT-BASED SUBSTRATES

Peat is frequently sold in a compressed form in order to reduce both volume and transport costs. The ability of peat to regain its initial volume (swelling capacity) after compression is an important feature of this organic medium and can have a dramatic effect on the final volume. Sometimes the natural swelling does not reach the volume expected. This can generate commercial controversy between the producer and the final user. Unfortunately, precise information regarding this matter is not so easy to gather. In order to understand which factors play a role on peat swelling capacity, some analytical trials have been carried out. The following factors have been studied: the degree of peat decomposition, the volume of water added the initial peat humidity, the peat particle fractions and finally the time interval between water application and volume measurement. Results show a significant effect arising from nearly all of the studied factors with the exception of the time interval between the application of water and the measurement of the volume. Practical applications could assist both substrate producers and growers to optimize the use of peat based substrates and also prevent conflicts from arising.