Anaerobically Digested Dairy Fiber in Soilless Potting Media for Herbaceous Perennials

Abstract

Sphagnum peat moss has been a primary component of soilless potting media for decades; however, concerns over the sustainability of harvesting peat have fostered a search for renewable media components. Anaerobically digested dairy fiber (ADDF), a by-product of methane production, shows promise as an alternative to peat. Herbaceous nursery crops including "Jack Frost" brunnera (Brunnera macrophylla I.M. Johnst), "Moonbeam" coreopsis (Coreopsis verticillata L.), "Whoopsa-Daisy" Shasta daisy (Leucanthemum × superbum Bergmans ex J.W. Ingram), "Kobold Original" liatris (Liatris spicata (L.) Willd.) and "David" phlox (Phlox paniculata L.) were grown in media containing bark-peat-perlite or bark-ADDF-perlite in a 4:2:1 proportion. All leachate was collected from pots to evaluate cumulative nitrogen and phosphate leaching. Brunnera grew to a similar size and quality in both mixes, although brunnera in the bark-ADDF-perlite mix had slightly chlorotic leaf margins. Coreopsis grew to a similar size and quality in both mixes but was slightly etiolated and chlorotic in bark-ADDF-perlite. Shasta daisy grown in bark-ADDF-perlite were larger than those grown in bark-peat-perlite. Both mixes produced similar growth and quality liatris and phlox. More ammonium, nitrate and phosphate were recovered from leachate from bark-ADDFperlite than from bark-ADDF-perlite.

Approaches for adding value to anaerobically digested dairy fiber

“…Properly treated, typically by composting or AD, organic wastes have the potential to substitute for peat and bark as components of the growth substrates in containerized plant production systems [37,46,47,48]. Specific to AD fiber, there is a small but growing body of research showing that AD fiber has the potential to meet the requirements for a component of high-quality growth substrates [49,50,51,52,53,54,55]. To produce container crops according to schedule, greenhouse and nursery growers must have reliable source of high quality growth substrates that are consistent over time and that have appropriate physical and chemical properties for their crops [34,46,56,57].…”

“…Root growth of plants in the experimental substrates was similar to the controls in both irrigation systems. In two recent works, Lamont and Elliot [54,55] Although not anaerobically digested, screened solids from a 1600-cow Florida dairy were processed through a horizontal drum digester or composter to produce a dairy manure peat-substitute marketed as cowpeat [61]). In experiments with foliage plants, Li et al [62]) replaced peat with cowpeat at 10 % increments from 10 to 60 % in 9 the propagation substrate for germinating Asparagus densiflorus seeds and for rooting cuttings of Epipremnum aureum, Philodendron scandens ssp.…”

Nutrient Recovery from Anaerobically Digested Dairy Manure Using Dissolved Air Flotation (DAF)

“…Anaerobic digestion is an increasingly common practice for producing renewable energy from manure, , but has little effect on P content and thus the byproductdigestatesuffers the same management constraints as raw manure . Emerging nutrient recovery technologies could address this issue by concentrating the nutrients in the digestate into forms that are easier to transport. , Primary solid–liquid separation is already commonly coupled with anaerobic digestion to recover coarse solids from the digestate, ,, which can be recycled on-farm as bedding, and also have potential commercial value as a renewable alternative to peat moss or a mushroom cultivation substrate . However, coarse solids separated via screw press typically contain less than a third of the digestate P and N, resulting in a subsequent liquid fraction retaining the majority of nutrients. , Numerous advanced nutrient recovery technologies have exhibited the potential to further partition P contained in the liquid digestate, − but have not been widely adopted due to unfavorable economics when solely considering the market value of recovered P products .…”

“…17 Emerging nutrient recovery technologies could address this issue by concentrating the nutrients in the digestate into forms that are easier to transport. 17,18 Primary solid−liquid separation is already commonly coupled with anaerobic digestion to recover coarse solids from the digestate, 16,19,20 which can be recycled on-farm as bedding, and also have potential commercial value as a renewable alternative to peat moss 21 or a mushroom cultivation substrate. 22 However, coarse solids separated via screw press typically contain less than a third of the digestate P and N, resulting in a subsequent liquid fraction retaining the majority of nutrients.…”