Submitted to: Acta Horticulturae
Publication Type: Abstract Only
Publication Acceptance Date: 9/7/2015
Publication Date: N/A
Technical Abstract: Biochar is the charred organic matter that remains after pyrolysis of biomass or manure. Biochars from different feedstock yield different properties as a result of their differing particle sizes at the time of pyrolysis, inherent ash content of the feedstock, pyrolysis conditions, and storage conditions after processing. The influence of biochar in mineral soil systems has been studied and reviewed extensively. The body of research in soilless substrates is far less complete than that for mineral soils; however, the collection of research thus far seem to indicate that same potential benefits in soilless substrates including additions of some nutrients, reduction in leaching of nitrates and phosphates, beneficial shifts in microbial populations, and improved physical properties. However, most of this work has limited applicability to production methods typical of floriculture crops in sphagnum peatmoss substrates. The objective of our research was to determine the physical, chemical, and biological effects of rice hull biochar on greenhouse substrates comprised primarily of sphagnum peatmoss. Additions of rice hull biochar up to 30% (by vol.) slightly increased substrate water holding capacity, decreased unavailable water, and increased substrate bulk density. However, these effects on physical properties are not likely to have an important influence on irrigation or other production practices. Rice hull biochar had no effect on substrate cation exchange capacity, but did increase substrate pH up to 1 point with 30% incorporation rate. The most important impact on substrate chemical properties from rice hull biochar was an increase in plant available phosphorus. Rice hull biochar exposed to higher-temperature pyrolysis regimes provided greater mass of phosphorus. Rice hull biochar had no measurable effect on geranium (Pelargonium xhortorum ‘Maverick Red’) susceptibility to pythium (Pythium ultimum).