Hydroponics 101

Krishna Nemali [email protected] (765) 494 8179 Topics :

• Production Systems • Substrate • Spacing • Varietal Selection • Germination • Nutrients • Temperature • Light • Winter Production Heating Supplemental Lighting Hydroponic Production Systems

Flood and Drain Tables Nutrient Film Technique Deep Water Culture

3-inches

12-inches Aeroponic Production Systems Aeroponic Towers Production Systems

Flood Table

Aeroponic Tower Production systems mostly differ in water use

Yield Water Use (grams per square feet) (liters per week per square feet) 160 2.5 140 2 120 100 1.5 80 60 1 40 0.5 20 0 0 Flood Table Nutrient Film Aeroponics Tower Flood Table Nutrient Film Aeroponics Tower Technique Technique Hydroponic Substrates

Peat Rockwool Peat substrates resulted in faster growth

Rock wool Peat Spacing (36 plants/m2)

1 m 6”

6”

1 m Spacing: Fixed NFT Benches 3 plants/ft2 or 32 plants/m2

6-inches 8-inches

Week 1 Week 2 Week 3 Week 4 Spacing: Sliding NFT Benches

1-inch 3-inch 6-inch 8-inch Week 1 Week 2 Week 3 Week 4 Lettuce Varietal Trial Germination

• Keep humidity high and plugs moist during germination • Use a dilute fertilizer solution (EC of 0.5 to 0.75 dS/m) • Light intensity can be low (100 to 150 µmol/m2/s) during the initial week • Preferred germination temp ~ 70 F or 21 C • Seedlings may need to be thinned, earlier preferred • Transplant seedlings prior to leaf overlap Nutrient requirement (combined data from 8 lettuce varieties and 2 production systems )

18 16 14 12 10 8 6 4 2 0 Yield ( grams per per plant) ( grams Yield 0 50 100 150 Nitrogen Concentration (ppm) Managing recycled fertilizer solution

* Control treatment received freshly prepared solution twice a week Negative effects of recycling appears after two weeks Negative effects can be reduced by discarding recycle solution after two weeks or using RO water Optimum greenhouse temperature

Air/solution at 60 °F Air/solution at 70 °F Light requirement Greenhouse production during winter

• Heating and supplemental lighting are required

• Energy costs for heating and supplemental lighting affect profits

• Productivity and energy efficiency should be increased for profits Greenhouse was maintained at cooler temperature to reduce heating costs Solution temperature was increased from 60 to 71°F

Maximize heating efficiency using root zone heating Greenhouse 60/50 F Heated Solution (70 F) Unheated Solution (60/50 F) Production system effects on root zone heating

Plant growth was better under flood tables than NFT when warm solution was supplied to roots

23

C) 22 °

21

20

19

18

17

16

Temperature ( Temperature 15 1 13 25 37 49 61 73 85 97 109 121 133 145 157 169 181 193 205 217 229 241 253 265 277 289 301 313 325 337 349 361 373 385 397 409 421 433 445 Time (hours from start) Air Reservoir solution NFT solution Flood table solution Lettuce growth is highly influenced by light spectrum

Full spectrum Red : Blue T8

Butterhead

Romaine

Red leaf

Green leaf Supplemental lighting at nighttime Increased productivity under Red (90%) : Blue (10%)

White R : B No SL Project Sponsors