Aquaponics Plant Side: Substrates, Biomass, Pest Management, and Lighting Options D. Allen Pattillo Aquaculture Extension Specialist Iowa State University  Nutrient management/ effluent  90% Less water mitigation consumption  Plants grow 2x as fast  Soil pathogens eliminated  Year round production possible  Plants can be grown  75% smaller footprint at desired height  Less space required per plant  No weeding!!!!  Vertical production allows more efficient use of space  Prolonged individual plant life Hydroponic Unit • Where the plants are grown • Must maintain moisture and high oxygen concentrations for plant roots • Options: • Floating raft • Flood and drain • Nutrient film technique • Towers • Aeroponics Cucumbers in a slab production system System design Drainage- Collection channels Drainage- Perforated plastic Drainage- Slope towards Drain or Drain Pipe Irrigation

• The irrigation for a hydroponic bag/bucket system is relatively simple: • Filter • Acid injector (if needed) • Fertilizer proportioners • Aquaponics slightly more complicated • Inflowing water must be clairified • Delivery tubes must be oversized to prevent clogging from bacteria Emitters for Hydroponics • Use oversized pipes to reduce the effects of biofouling • dissolved organic matter promote the growth of filamentous bacteria • restricts flow within pipes • Spaghetti tubes will likely clog • Tilapia in drain lines reduce biofouling by grazing on bacteria • Pipes downstream from solids removal are less likely to clog • Lower water temperatures reduce biofouling Slab Substrates

• There are two primary substrates used in slab or bag culture

1) Rockwool

2) Coconut coir

3) Perlite (to a lesser extent) (discussed later on under bucket culture) Rock wool

fa.wikipedia.org Rockwool Propagation Cells Rockwool Blocks Rockwool Slabs Advantages of Rockwool

• Less chance for disease to spread (in open systems) • Disease may occur in aquaponics because water is recycled as opposed to drain-to-waste

• Uniform application of nutrient solution to plants (fed individually with drippers)

• Lightweight material is easy to handle

• Easy to heat substrate

• Pasteurized easily for reuse (3 to 4 yrs) Advantages of Rockwool

• Rapid crop turnaround, minimal labor

• Good aeration of root zone

• Less risk of crop failure from irrigation failure (compared to NFT)

• Little lag/setback from transplanting • Root system is not disturbed

• Less capital investment (compared to NFT) Disadvantages of Rockwool

• Relatively expensive • If not locally manufactured (most places)

-, - • Undesirable ions (CO3 , Na ) can accumulate if irrigation water quality is poor • Use higher-quality water (i.e. reverse osmosis) in this case Rockwool alternative? • One of the challenges associated with rockwool is the disposal • Questions about sustainability

• Growers were looking for an alternative

• The development of coconut coir provided a new alternative Coir

sanctuarysoil.com Inhabitat.com

efundies.com www.vgrove.com Coconut Coir • Coconut coir is the ground husk from coconut palms • Large producers include Philippines, Indonesia, India, Brazil, Sri Lanka, and Thailand

• Coconut husk can be ground to different sizes

• For lose mixes it can be mixed with other substrate components • Perlite, vermiculite, peat moss, etc.

• For bag culture 100% coconut is used Preparing Coconut Coir • Coir bags come in a compressed form

• Irrigate or soak bags to decompress the coir and increase the volume of the bag • 24-hr of irrigation (drip) is sufficient

• Sometimes coir may need to be soaked to leach out excess sodium • This is usually needed with the loss coir, not slabs Coconut Coir Production Scheme

• The production scheme for coconut coir bags is the same as rockwool

Plugs

Blocks

Slabs Advantages of Coconut Coir

• Closed system can conserve water and nutrients

• High air-holding capacity

• Capillarity is good, permitting better dry down cycles

• Dry spots do not occur from because coir rewets easily

• Different particle sizes allow for blends for specific uses Advantages of Coconut Coir

• Root growth is strong due to high air to water ratio

• Coir slabs can be pasteurized and used for more than one season

• 100% organic material eliminates any disposal issue

• Coir can be inoculated with beneficial organisms to reduce Pythium infections Disadvantages of Coconut Coir

• If in a closed system, the potential for pathogens can be high

• Coir needs to be prepared adequately to reduce sodium levels

• Coir may contain potassium, so fertilizer regimes may need to be adjusted to account for this addition Dutch or BATO buckets Dutch/BATO Buckets

• This is another type of hydroponic system where the substrate plays a large role in the production of plants

• There are several similarities to the bag/slab growing

• The primary difference is in the type of substrate Dutch/BATO buckets BATO buckets

Black White (cool-season) (warm-season) Dutch bucket System design • From the water source to the drip emitters system design for Dutch buckets is the same as rockwool slabs

• Buckets are then filled with substrate and plants are placed in the bucket • 3- to 4-inch wide rockwool blocks or coconut blocks Bucket design

• The design of a bucket is simple:

• Drip emitters for delivering nutrient solution

• A siphoning elbow drains excess nutrient solution from the bucket

• The elbow drains excess leachate into a PVC pipe Overview

Siphoning elbow

PVC pipe for drainage Irrigation

• Irrigation for Dutch buckets is similar to that of slabs/bags

• Individual emitters are placed at each plant in the bucket

• Excess solution is drained out of the bucket, but a small reservoir remains at the bottom Perlite

www.fabsreptiles.co.uk Hydroton • Organic solids may tend to clog aggregates such as pea gravel, sand and perlite • Creates anaerobic conditions (low DO) • Kills plant roots • Kills beneficial bacteria • Can be mitigated by adding worms to aggregate substrate to process organics Column culture Column culture

VertiGrow is a proprietary column culture system. Interlocking styrofoam containers are stacked on top of one another Column Culture • Column culture can be similar to bag/bucket culture

• Nutrient solution is delivered through emitters to the growing substrate in the containers

• Drippers may need to be placed throughout the column to avoid nutrient build up or a nutrient gradient Raft system at Cornell Controlled Environment Agriculture Facility Raft or raceway system Raft or raceway system Here

Plant Harvest Different spacing for nursery channels or different crops Nutrient film technique- NFT Troughs are initially spaced out Calculating a slope

% slope = (rise/run) × 100 % slope = (∆h/d) × 100 The flow rate of NFT solution is important

The flow of solution should be maintained between 1 and 2 liters per minute Harvesting is easy! Spiral NFT systems (not commonly used in production) Ridged channels on the bottom of troughs

This can help keep water from channeling from one side to the other Nursery channels may be used to save on space

Young plants at a high density to save on space

Nursery channel

Finishing channel Time to transplant!

Generally, crops are ready to be transplanted into NFT or raft systems when there are at least two true leaves (or two pairs of true leaves) and when the roots have penetrated the base of the cube Substrates for propagation • For the raft and NFT system there are several types of substrate used to propagate plants: • Rockwool • Phenolic foam (“Oasis®”) • Stabilized peat substrates

• The substrates for rafts and NFT play a much smaller role in production compared to slab/bag systems Rockwool Phenolic foam

aquaponicsideasonline.com Stabilized soilless peat substrates

hydrogarden.com Stabilized coconut coir substrates

growerssupply.com Water • The quality of the water used is important • Maintain micronutrient availability

• The pH and alkalinity are the first things to check • Target pH of 5.8 to 6.2 in germination (this varies with crops) • pH of the aquaponics system should be 6.5 - 7

• What to look for (problems): • Sodium (Na+), Chloride (Cl-) and chloride (Cl), fluoride (Fl-), and iron Mineral Nutrition • Mineral nutrients are dissolved and provided with irrigation in hydroponics • “Nutrient solution” • Provided from broken down feed and feces in aquaponics

• Nutrients are constantly applied to crops • Clear water is rarely, if ever, used

• Fertilizers come in one of three types for straight Hydroponics: 1) Complete (one bag) 2) Complete (two bag, “A” and “B” tank) 3) Individual salts (custom formulation) Light • For hydroponic production, we are primarily concerned with photosynthetic light

• The growth (biomass accumulation) of plants is primarily affected by light

“A 1% increase in light is a 1% increase in yield” Light • In order to maximize growth of herbs, supplemental light is useful

• High-pressure sodium (HPS) lamps are useful for increasing the DLI in a greenhouse

• LEDs are a potential for use in production • Research on the effects of light quality on flavor is needed! Increasing light increases shoot growth

12

11

10

9

8 Shoot fresh weight (g) weight Shootfresh

7

6 100 150 200 250 300 350 400 450 500 550 600 Light intensity (umol) Temperature

• Temperature affects the rate of plant growth • Not necessarily the size!

• This is important for the timing of your crops

• Growing plants outside of optimal ranges can delay production Air temperature (°F) 46 50 54 58 62 66 70 74 78 82 86 Parsley Chives Dill Mint Oregano Cilantro Rosemary Sage Basil O2

• Oxygen in the nutrient solution is very important • Especially for the water-based systems!

• In order to maintain good levels of dissolved oxygen, aeration is needed

• Saturation is around 8%-10% Aquaponics vs. Hydroponics

“Balanced” Aquaponic Production Strategies

Plant Issues Observed Low Dissolved Oxygen Aeration • ADD AERATION WHENEVER POSSIBLE! • Aids in oxygenation and off-gassing of unwanted toxins • Helps fish, plants, and bacteria perform critical biological processes

• Aeration options • Diffuser stones • Venturi action • Packed columns • Waterfall action Nutrient Deficiencies Yellowing, reduced growth rates, and reduced flavor quality can be caused by nutrient imbalances • Plants require 13 nutrients for growth, and fish feed supplies 10 nutrients in adequate quantities. • Iron • Chelated Iron (EDTA) • Calcium • Agricultural Limestone

• Calcium Carbonate (CaCO3) • Hydrated Lime

• Calcium Hydroxide (Ca(OH)2)

• Calcium Chloride (CaCl2) • Potassium • Muriate of Potash • Potassium chloride (KCl) • Potassium Hydroxide (KOH)

Pest Management Issues • Pesticides must not be used to control insects and plant diseases because many are toxic to fish and none have been approved for use in food fish culture. • Therapeutants for treating fish parasites and diseases may harm beneficial bacteria and vegetables may absorb and concentrate them. Lighted Insect Traps Sticky Traps Diatomaceous Earth

Insect Screening Parasitic Wasp Lady Bug Praying Mantis Bacillus thuringiensis (Bt)

Essential Plant Oils Implications of Plant Culture Method for Plant Growth in Aquaponics Types of Growout Basil Standard1,2 Pea Gravel Floating Raft Rockwool Requirements Nutrient Concentration (mg/L) + Ammonia (NH4 ) 2.2 0.0 - 4.97 0.128 - 2.04 0.088 – 0.856

Nitrate (NO3) 0.4-82.2 20.2 – 24.2 35 - 111 25.3 - 110

Nitrite (NO2) 0.7 0.08 – 7.54 0.0-2.14 0.084 – 1.42

Alkalinity (CO3) 113.2 42 - 96 43 - 240 26 - 93 Calcium (Ca) 10.7-82.1 491 – 726* 150 – 780* 452 – 727* Phosphorus (P) 0.4–15.3 0.807 – 4.97 1.68 – 40.1 1.05 – 6.05 Iron (Fe) 0.13–4.3 0.04 – 0.536 0.145 - 0.688 0.21 – 0.509 pH 7.1 - 7.4 6.53 - 8.12 5.43 – 7.9 6.39 – 8.04 Dissolved Oxygen (DO) 4.0 - 5.0 3.29 – 8.15 2.55 – 8.01 5.0 - 8.2 Temperature (°C) 29 - 31 19.4 – 27.6 21.2 – 28.8 17.4 - 26.9

* Total Hardness measured 1 – Rakocy, J., Shultz, R.C., Bailey, D.S. and Thoman, E.S. 2004. AQUAPONIC PRODUCTION OF TILAPIA AND BASIL: COMPARING A BATCH AND STAGGERED CROPPING SYSTEM. Acta Hort. (ISHS) 648:63-69 2 – Rakocy, J. 2011. Aquaponics Q and A. Nelson and Pade, Inc. Plant Growout

Lettuce Basil Days to 46 78 Maturation Density 26 26 (plants/m2) Retail Price ($/kg) $10.96 $79.02 Produce In March of 2012… Average Individual Lettuce Produce Weight

400

a 300

a 271.1 a

200 218.3 210.1

100 b

Lettuce Produce Weight (g) Weight Produce Lettuce

62.5

0 Floating Raft Soil Pea Gravel Rockwool Conclusions • Which substrate is best?... • Well…what’s your goal? Largest plants Best environment for fish Least water consumption Which earns the most money? Iowa Retail Prices as of 2/20/2013

Tilapia Lettuce Basil (fillets) Retail Price $10.96 $79.02 $15.36 ($/kg) Average Tilapia Production Value =

Average Total Weight per Tank (kg) 5.95 Fillet Yield (kg) (35% dressout) 2.08 Retail Value Per Tank ($15.36/kg) $31.99 Production Value ($/m3) $202.48 Lettuce Production Value Average tray Retail Production #/ Biomass Treatment Produce area Value Value tray (kg/m^2) Weight (g) (m^2) ($/kg) ($/m^2) Floating 218.3 8 0.6 2.91 $10.96 $31.90 Raft Soil 62.5 8 0.6 0.83 $10.96 $9.13 Pea 271.1 8 0.6 3.61 $10.96 $39.62 Gravel Rockwool 210.1 8 0.6 2.80 $10.96 $30.70 Supplemental Lighting • Necessary for winter months and indoor culture • Efficiency is critical to economic viability • Light spectrum and photoperiod affects fruiting of plants • Options: • High Pressure Sodium • Florescent • Halogen • Light Emitting Diodes (LED) LED vs. HPS

HPS Lighting •High Pressure Sodium Lamps • 400 watts

•Photoperiod • 16L : 8 D LED Lighting •Light Emitting Diodes • 1,000 watt HPS equivalent •Photoperiod • 16L : 8 D

LED Wet Basil LED HPS Wet Basil Value ($/m2/yr) $745 $405 Net Benefit ($) $434.89 $47.63

Questions?