Evaluation of dairy biofiber processed by hydro-cyclone and in-vessel composting as an alternative to peat in containerized greenhouse production.

摘要

Dairy biofiber (DBF) is a processed dairy manure product that may have potential to become an alternative component to the use of sphagnum peat (peat) in the formulation of substrates used in containerized production. The objective of this research was to evaluate DBF as an alternative root substrate component for the use in general horticulture production. This was done by comparing physical properties, chemical properties and plant growth responses of DBF to those of peat. The root substrates containing DBF were blended with either perlite, bark or parboiled rice hulls (PBH) as an aggregate and peat as the remainder component. The total pore space, water-holding capacity, and the bulk density of 100% DBF root substrate were higher when compared to the 0% DBF control. However, the 0% DBF root substrate displayed greater air-filled pore space. Root substrates containing increasing concentrations of DBF displayed higher water-holding capacity in the laboratory and greenhouse. Days required to dry to 50% moisture content (w/w) and days to complete drying increased independently of the aggregate used (perlite, bark or PBH) for those root substrates containing DBF. The pH and EC values increased as the concentration of DBF in the root substrate increased. The 80% DBF replacement in a root substrate had a pH and EC of 8.1 and 3.5 dS·m-1, respectively. DBF cannot be used as a complete replacement for peat. Most of the macro and microelement concentrations increased as the percent DBF increased in the root substrate. Ammonium and sulfur concentrations decreased as the percent DBF increased. The macro and microelement concentrations were within the recommended ranges for greenhouse crop production. Elemental sulfur and iron sulfate were used as amendments to lower the pH and EC of DBF-containing root substrates over time in the greenhouse. However, none of these materials had an effect on the pH and EC of DBF- containing root substrates. Dairy biofiber was blended at 30% to 40% replacement of peat in a root substrate and this mixture displayed adequate pH and EC values for growing crops. The days to first flower, shoot height, shoot dry weight, and dry root weight of viva, impatiens and geraniums grown with increasing concentrations of DBF were similar to those grown with 0% DBF. Dairy biofiber does have the potential to become a standard alternative component to the use of peat in containerized production.