9/19/2014. Alternative Media Components and their Potential Advantages and Limitations. Why do we need new components?

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Nathan McDaniel
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Properties of growing media and their constituents that pertain to quality.

stability nutrient content viable propagules consistency of water capacity organic

Michael Evans, University of Arkansas air capacity bulk density wettability * G.

life cultivation technique plant requirements price Far fewer options for alternatives

Most common component still used and most effective in most situation is peat.

Coconut Coir Coir with minimal fiber is typically best for plugs and cuttings.

1 Alternative Media Components and their Potential Advantages and Limitations Why do we need new components? Always on the look out for something better and cheaper! Properties of growing media and their constituents that pertain to quality. * PHYSICAL CHEMICAL BIOLOGICAL ECONOMIC structure ph weeds, seeds and availability stability nutrient content viable propagules consistency of water capacity organic matter pathogens quality Todd Cavins, Ball Horticultural Co. Michael Evans, University of Arkansas air capacity bulk density wettability * G. Schmilewski, 2008 noxious substances buffering capacity pests microbial activity storage life cultivation technique plant requirements price Far fewer options for alternatives with plugs and cuttings. Smaller substrate volume. More sensitive cuttings and seedlings. Most common component still used and most effective in most situation is peat. Type and grades of peat vary with respect to properties and best use. Coconut Coir Coir with minimal fiber is typically best for plugs and cuttings. Be careful of high E.C. and remember ph is different from Sphagnum peat. Coir typically holds more water and has less air space than a typical sphagnum peat. Coir may be disease suppressive. 1

coir; autoclaved seed treatment peat; autoclaved peat;

coir; autoclaved peat; unautoclaved peat; autoclaved coir;

Cork Vermiculite is often used as a top coating substrate for

Various issues have promoted a desire for alternative top

Ground cork is a by-product from the production of various

Placed in polycarbonate-glazed greenhouse at temperature set

2 coir; autoclaved seed treatment peat; autoclaved peat; unautoclaved coir; unautoclaved Phytotophthora nicotiana coir; autoclaved peat; unautoclaved peat; autoclaved coir; unautoclaved Phytotophthora capsici seed treatment Ground Cork Vermiculite is often used as a top coating substrate for plug production. Various issues have promoted a desire for alternative top coating materials. Ground cork is a by-product from the production of various cork-based products. Placed in polycarbonate-glazed greenhouse at temperature set points of 19 C and 22 C. Cork may be ground and screened to produce several sizes. Frequent misting used to maintain moist top coat. Plugs fertilized with 50 ppm N after first true leaves began to develop. 2

3 Physical Properties Physical Properties ** *** *** Orbital Cardinal Red Geranium Orbital Cardinal Red Geranium Orbital Cardinal Red Geranium Score Deep Red Geranium 3

4 Dazzler Lilac Splash Impatiens Rutgers Select Tomato Better Belle Pepper Ground Parboiled Fresh Rice Hulls Physical properties depends on grind size. Some grind sizes have physical properties very similar to sphagnum peat. 4

Differences in chemical properties from sphagnum peat but at 30-40% of substrate are within acceptable ranges.

Physical properties vary with degree of composting.

1 Peat Chemical properties varying with degree of composting and composting method.

5 Differences in chemical properties from sphagnum peat but at 30-40% of substrate are within acceptable ranges. Composted Rice Hulls Hull has been broken down to produce a small particle size. Dark brown to black in color. Physical properties vary with degree of composting. Composted Hulls Total pores 85% 85% Air-filled pores 18% 15% Water-holding 67% 69% Bulk density Peat Chemical properties varying with degree of composting and composting method. composting method amount and source of N pile age Typical ph of 5.4 to 5.7 and E.C. of 0.5 to 0.7 mmho/cm. Macro- and microelements usually within acceptable ranges and not problematic so long as acceptable ph maintained. Important to know source. Test new batches of material. 5

Biochars Oxidized (burned) organic matter under low oxygen conditions.

feedstock and the process greatly impact the products properties.

Various types have been used successfully in trials and a mix component.

1 Miscanthus 9.3 1.7 Cotton gin 7.1 4.6 Rice hull 7.2 0.2 Pine shavings 4.6 0.

and overhead irrigation. Variability and consistency can be a problem.

6 Biochars Oxidized (burned) organic matter under low oxygen conditions. Process using various methods including torification (torrefacation), pyrolysis and gasification. Processes varying in temperature and time and impact properties Biochars The feedstock and the process greatly impact the products properties. Therefore, highly variable in physical and chemical properties. Various types have been used successfully in trials and a mix component. Biochars Biochars Feed stock ph E.C. (ms/cm) Poultry litter Poplar Miscanthus Cotton gin Rice hull Pine shavings Vinca (L) and Geranium (R) in biochar-containing mixes fertilized with 200 ppm N and overhead irrigation. Variability and consistency can be a problem. Chemical properties of some can be a problem. Do not tend to absorb water very well. Probably very limited use in substrates for plugs and cuttings. Rooting Cubes Numerous types including Oasis foam, rockwool and peat-based materials. 6

Push out of seedlings can be a problem in some types of cubes.

Worm Casting & Vermicompost The practice of using worms to degrade organic materials Vermicompost =

0 EC: 5+ ms/cm (SME) Bulk Density: 10 15 lbs/ft 3 Worm Casting & Vermicompost Worm Casting &

variable Vermicompost is not acceptable to be used as the major component in a mix (Mota et al.

aeration decreases (Bachman & Metzger, 2007) Levels greater than 15% provide high levels of P limiting

7 Push out of seedlings can be a problem in some types of cubes. Especially problematic with spinach, lettuce and some other types of greens. Worm Casting & Vermicompost The practice of using worms to degrade organic materials Vermicompost = poop plus the bedding, etc. Worm Castings = just poop (finished) ph: EC: 5+ ms/cm (SME) Bulk Density: lbs/ft 3 Worm Casting & Vermicompost Worm Casting & Vermicompost The feed and bedding used can be highly variable, so the end product can be highly variable Vermicompost is not acceptable to be used as the major component in a mix (Mota et al., 2007) As vermicompost is increased, bulk density increases, water holding capacity increases, and aeration decreases (Bachman & Metzger, 2007) Levels greater than 15% provide high levels of P limiting Target volume of vermicompost: 10% (volume) Minimal impact on EC and ph Still provides some level of nutrient and biological activity Moisture retention mycorrhizal activity and potentially causing plant stretch. (Miller et al, 1997) 7

Greenwaste Compost Greenwaste Compost Vital Earth, Ashbourne, UK Vital

yard waste Ideally grass, leaves and limbs Caution! What else?

0 + ms/cm (SME) Bulk Density: 25-31 lbs/ft 3 Greenwaste Compost Good

ph Some are good suppliers some are not Stability and N-draw down

8 Greenwaste Compost Greenwaste Compost Vital Earth, Ashbourne, UK Vital Earth, Ashbourne, UK Greenwaste Compost Greenwaste Compost Vital Earth, Ashbourne, UK Vital Earth, Ashbourne, UK Greenwaste Compost Composted yard waste Ideally grass, leaves and limbs Caution! What else? Herbicides, CCA wood, plastic, coat hangers ph: EC: ms/cm (SME) Bulk Density: lbs/ft 3 Greenwaste Compost Good microbial activity Good CEC Heavy Shipping, aeration Micronutrients and ph Some are good suppliers some are not Stability and N-draw down Limited substitution 8

9 Wood Fiber Wood Fibers Two thermo-screw presses shred wood chips under pressure using steam Can be impregnated with nutrients ph: EC: ms/cm (SME) Bulk Density: lbs/ft 3 Wood Fibers blended with Peat* Wood Fibres Good physical properties Sustainable Prevents shrinkage Bill Carlile, Bord Na Mona Now readily available in the U.S. $$$ for manufacturing equipment N draw down Splinters * G. Schmilewski, 2008 Available for Growing-on mixes Silicon is a beneficial plant nutrient Thicker, stronger stems Increased drought tolerance Resistance to insects and diseases Dense, more compact plants Increased tolerance to ph drift S. Kamenidou,

10 Typical Silicon Results Brussels Sprouts Brussels Sprouts Brussels Sprouts Brussels sprouts plugs produced in Resilience mix developed earlier than those grown in the standard mix. Brussels sprouts rooted better in Resilience mix than in standard mix. Pepper Tomcat Week 23: 7 weeks after sowing Tomato Bobcat Peppers rooted better in Resilience mix than in standard mix. 10

Tomato Bobcat Tomato Bobcat Tomato plugs

Sunflower rooting was about the same in both

after sowing after sowing Miscanthus rooted

11 Tomato Bobcat Tomato Bobcat Tomato plugs produced in Resilience mix developed earlier than those grown in the standard mix. Tomatoes rooted better in Resilience mix than in standard mix. Sunflower Sunny Smile Zinnia Magellan Cherry Sunflower rooting was about the same in both mixes. Zinnias rooted better in Resilience mix than in standard mix. Miscanthus Ornamental Grass Week 25: 9 weeks after sowing Miscanthus Ornamental Grass Week 25: 9 weeks after sowing Miscanthus rooted better in Resilience mix than in standard mix. 11

Ground Cedar Ground Cedar Historically we have said Cedar (Juniperus virginiana) is allelopathic. Likely not Kansas State and Auburn Universities say otherwise.

Freedom Red poinsettias 8 weeks after transplant into bark-based substrates with 0% and 30% bark replaced with cedar. Table 3.

12 Ground Cedar Ground Cedar Historically we have said Cedar (Juniperus virginiana) is allelopathic. Likely not Kansas State and Auburn Universities say otherwise. Nursery and finished greenhouse focus not plugs Ground Cedar Cedar will work! Figure 1. Freedom Red poinsettias 8 weeks after transplant into bark-based substrates with 0% and 30% bark replaced with cedar. Table 3. Physical properties of bark mixes with distilled cedar chips replacing bark or perlite components. Treatment Total Porosity (%) Container Capacity (%) Air Space (%) Dry Bulk Density (g/cc) Control 10 BR 20 BR 30 BR 94.2% 75.2% 19.0% % 61.5% 21.9% % 8.2% 31.9% % 10.3% 31.4% 0.10 Table 4. Physical properties of peat mixes with distilled cedar chips replacing perlite. Figure 3. Pinto Red geraniums 5 weeks after transplant into peat-based substrates with 0% and 35% perlite replaced with cedar. Treatment Control 5 PR 15 PR 25 PR 35 PR Total Porosity Container Dry Bulk Density Air Space (%) (%) Capacity (%) (g/cc) 86.4% 60.2% 26.2% % 51.3% 36.5% % 12.7% 23.6% % 7.6% 32.2% % 10.5% 32.5% 0.10 Lots of others Little Info or Limitations Composted Manure Nut shells/hulls Straws Kenaf Bagasse Grape Marc Plastic foams Todd Cavins Ball Horticultural Company tcavins@ballhort Michael Evans University of Arkansas mrevans@uark.edu 12

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