Student Laboratory Exercise to Understand Air and Water Relations in Container Substrates

in HortScience
Authors:
E. Jay Holcomb1Dept. of Horticulture, The Pennsylvania State Univ., University Park, PA 16802

Search for other papers by E. Jay Holcomb in
ASHS
Google Scholar
PubMed
Close
,
Robert Berghage2Dept. of Horticultural Sciences, North Carolina State Univ., Raleigh, NC 27695

Search for other papers by Robert Berghage in
ASHS
Google Scholar
PubMed
Close
, and
William Fonteno2Dept. of Horticultural Sciences, North Carolina State Univ., Raleigh, NC 27695

Search for other papers by William Fonteno in
ASHS
Google Scholar
PubMed
Close

The concepts of container water-holding capacity and air-filled porosity are important yet complicated for students interested in containerized crop production; however, both of these concepts can be observed and understood more completely if students develop a moisture retention curve. Our objectives were to describe an easy-to-construct and economical apparatus for creating a moisture retention curve and then to compare this curve with one generated by standard methods. The student method (column method) is constructed from plastic pipe cut into 5-cm sections. The sections of pipe are individually packed with a substrate then stacked and taped together, resulting in a 60-cm column of the substrate. The column is saturated and allowed to drain for 24 h. Then, the column is taken apart and the water content of each section determined gravimetrically. The water content of each section is graphed against height so that the result is a moisture retention curve. Data are presented to show the curve developed from the column method is similar to the curve developed by standard soil moisture tension method. The moisture retention curve can provide a better understanding of water and air holding capacities of substrates.

  • Collapse
  • Expand