Lesley Judd

Former Graduate Student

Degree: Ph.D., 2016

Dissertation: Analyses of Consistently Made Biochar for Chemical and Physical Properties and Their Effects on Container Substrates

The use of biochar as a soil amendment has garnered much attention due to its potential in increasing plant growth, soil fertility, soil water holding capacity and carbon sequestration. However, the available literature on this topic suggests that biochar either has a negative, positive or neutral effect on plant growth in soils and greenhouse substrates. What does this mean and why is it happening? One of the major issues presented within the literature is the fact that biochar is a term given to any charred organic material, whether made from poultry litter or palm trees. Each feedstock will produce a different biochar product physically and chemically. The processes to produce biochar can also range from small dirt kilns to large industrial reactors. There is a need for certain processes of producing biochar to be examined for the capability to reliability produce quality biochar. All types of biochar should be characterized for their physical and chemical attributes. For the nursery and greenhouse industry, biochar has several potential uses that need further investigation. There is potential for biochar as an aggregate due to its potentially positive effect on shoot and root growth, and the possibility of reduced production time in plant propagation. Smaller particle sizes of biochar have potential use for raising pH in substrates and aiding in substrate pH buffering capacity due to its naturally high pH. To investigate these potentials, biochar will be produced at NC State using a top-lit updraft gasifier using pine wood chips and rice hulls as feedstocks. The biochar products will then be tested for chemical properties, including cation and anion exchange capacity, nutrient concentration and nutrient adsorption. The pH of biochar and its potential pH buffering capacity will also be determined. Biochar will also be tested for physical properties, including particle size distribution, internal and external surface area and water holding capacity. These further characterizations of biochar produced from pine wood chips and rice hulls will aid in investigating the potential uses of biochar in the nursery and greenhouse substrate industry.


Lesley A. Judd