Winter High Tunnel Environments: Managing and …...Winter High Tunnel Environments: Managing and Monitoring Illinois Specialty Crop Conference Springfield, IL January 8, 2020 Liz

Winter High Tunnel Environments: Managing and Monitoring

Illinois Specialty Crop ConferenceSpringfield, IL

January 8, 2020Liz MaynardDept. of Horticulture and LA, Purdue [email protected]

mailto:[email protected]

E. Maynard, 2020Purdue University is an equal access/equal opportunity institution.

Purdue University is an equal access/equal opportunity institution.E. Maynard, 2020

• Solar radiation / light• Temperature• Relative humidity (RH)

The Environment


•Photosynthesis•PAR measured in µmol / m2 / second•DLI measured in mol / m2 / day

Light


0

5

10

15

20

25

30

9/24 10/20 11/15 12/11 1/6 2/1 2/27

Daily

Ligh

t Int

egra

l (m

ol/m

2/da

y)Daily light integral (DLI) in an unheated high tunnel in Northern Indiana in

fall and winter 2015 - 2016


Time of Year Influence on Light

0

5

10

15

20

25

30

35

40

September October November December January February March

DLI (

mol

/m2/

day)

Expected DLI in fall and winter for representative locations in Northern, Central, and Southern Indiana

Northern Central Southern

J F M A M J J A S O N D J

Hours of Daylight

10

12

14

DLI estimate from 1998-2012 solar radiation, Faust and Logan, 2018.


Orientation

High Tunnel Structure and Light

North South

NorthNorth

South

South

• Orientation• Shape• Covering• Shade

ShapeCovering


High Tunnel Covering


Photosynthetically Active Radiation in High Tunnels and Solar Radiation at Pinney Purdue Ag Center, July 7-13, 2018

Plastic removed on July 9

New plastic

installed on

July 12

ET MaynardSolar radiation data obtained from iclimate.org, 7-17-2017.


ET Maynard

Daily Light Integral in High Tunnels and Solar Radation at Pinney Purdue Ag Center, July 7-12, 2018

Solar radiation data obtained from iclimate.org; 7-17-2017. Two missing data points for 7/10 estimated based on PAR levels at HT 1.


• Consider single layer plastic• Remove snow/ice• Remove shade sources• Remove row covers during the

day• Supplemental light?

Managing Light


Managing Light


Shade from Row Covers


Shade From Row Covers

Row Cover Off Row Cover OnDaily Light

Integral (DLI)DLI Inside as % of

Daily Light Integral (DLI)

DLI Inside as % of

Date Outside Inside Outside Date Outside Inside Outside(mol/m2/day) (mol/m2/day)

12/01/16 4.2 2.9 69% 12/11/16 5.1 2.3 46%01/24/17 4.0 2.9 73% 01/28/17 3.9 1.9 48%02/11/17 13.1 10.2 78% 02/04/17 12.8 6.5 51%02/13/17 27.1 19.3 71% 02/09/17 27.5 13.2 48%03/24/17 37.1 24.7 67% 03/15/17 38.9 19.2 49%Average 72% 48%

Row cover 0.55 oz./sq. yd. spun-bonded polyester


• Plant growth• Optimum• Base• Average daily temp and

growing degree days • Low temperature injury• High temperature injury• Influences on seed dormancy,

flowering, bolting• Soil temperature

Temperature


Energy Flow and Storage

Energy exchange between a greenhouse and the surroundings, showing the sun as the main source of energy. (Adapted by M. O’Donnell from Figure 4-1, Aldrich and Bartok, 1989)

Infra-red thermal radiation from atmosphere

Infra-red thermal radiation from surfaces

Air exchange through vents

TranspirationEvaporation

Infra-red thermal radiation from plants

Reflected sunlight

Reflected sunlight

Sun


Energy Flow and Storage

Heat loss from a greenhouse. (Adapted by M. O’Donnell from Figure 4-2, Aldrich and Bartok, 1989)

Radiation to cold sky

Infiltration (cold air)

Exfiltration (warm air)

Convection

Conduction into ground

Conduction to air

Cold outside air

Perimeter conduction

Convection

Cold sky

Mean Temp

Solar Radiation and DLI

19

Average Temperature and Daily Light

RR_min_air-tempWITHOUTHEATED-vs-date-overlayRR_daily-radiation-and-DLI-graph 63

Min. Daily Air Temp Outside and In – Determines what will survive

Daily Solar Radiation and Light

Outside

Minimum temperature determineswhat will survive

Under row cover 5-10°F warmer than above, 10–20°F warmer than outside

Daily Minimum Air Temperature Outside and in High Tunnel (unheated) and Low Tunnel,RR, 2015-2016

RR_ave_soil-temp-vs-date-overlaySepMarRR_daily-radiation-and-DLI-graph

Daily Solar Radiation and Light

69

Air temp and solar radiation in Feb. Data from CB, 2016

Air Temperature and Solar Radiation for a Week in February 2016

Air temp in tunnels increases quickly when the sun comes out.

Air under row cover in tunnel

Air above row cover in tunnel

Air outside

64

Air temp and SR in Feb, 1 day Data from CB, 2016

Temperature Increases Quickly When the Sun Comes Out!

Air under row cover in tunnel

Air above row cover in tunnel

Air outside

Data from Clay Bottom, 2016 65


•Maximize light• Increase heat sinks• Dark mulch• Raised beds•Moist soil

•Reduce losses• Double layer poly, IR poly• Sealing gaps• Insulation•Windbreaks• Row covers

Temperature: Keeping it Warm


• Spun-bonded polyester• Light, medium, heavy weight

Row Covers to Trap Heat Near Crop


•Plant water relations• Leaf size and thickness, physiological disorders•Disease

Relative Humidity


Time of Year Influence on Light, cont.

20

30

40

50

60

70

80

°F

Air Temperature, Unheated

50

60

70

80

90

100

110R

H %

Relative Humidity, Unheated

Relative humidity was near 100% at night and decreased as the tunnel warmed up during the day.

In early afternoon, relative humidity dropped quickly and so did temperature; the tunnel was vented to let in cooler outside air, which was also drier. If a row cover was present it may have been removed also.

Relative humidity and air temperature in unheated high tunnel in northern Indiana on Feb. 17, 2016.

12 AM 4:48 AM 9:36 AM 2:24 PM 7:12 PM 12 AM


• Vent• Automation very helpful

• Remove row covers during day• Manage drainage

Relative Humidity

A Draft Framework for Thinking About Environmental Management

Time of Year Mode DangerSept. – Oct. growth, acclimating overheating

Nov. slow growth cold injury

Dec.-Jan storage, surviving, veryslow growth

cold injury, disease

Feb. – Mar. slow to faster growth cold injury, overheating, unwanted bolting

April growth overheating, unwanted bolting

60

Managing the Environment – Standard Daily/Seasonal Practices

• Watch forecast. Not just daily, but leading up to harvest to anticipate ideal windows for harvest. Monitor internal temperatures (if you have sensors)

• Anticipate venting and row cover removal in late morning and closing/covering in afternoon for temperature and RH management. Uncover to reduce RH, and increase solar radiation gain to soil. Vent to reduce RH, limit high temp.

• Multiple layers of row cover may be needed incrementally as temperatures drop.

• Do NOT remove covers early after freezing nights or you risk damaging plant tissue.

75

Managing the Environment – Standard Daily/Seasonal Practices• Some growers leave peak vents slightly vented at all times. Little air

exchange will occur if no side wall or lower vents are open. Management is

then reduced to side wall venting and row covers.

• Remove snow or ice to limit structural stress

• Emergency heater for extreme low temp situations?

• Insulate end walls, and north walls?

• Row covers not typically used in minimally heated tunnels. Low temp

threshold set at ~28 F (depends on crops and your fortitude)

• Make close observations by crop, variety, weather conditions, mgmt., and

keep records.

• In fall keep tunnel vented to “harden” off or “acclimatize” the plants to low

temps until absolutely necessary to close. Don’t baby your plants!

76

Minimally Heated TunnelsBenefits

–Less hardy crops survive for more diverse mix in mid-winter–Faster growth means higher yield–No need for row covers

Heating systems–Air - unit heaters are common–Soil - hydronic, air-to-air, electric

Temperature Management–What temperature? 28? 33? 40?–Manage for average daily temperature instead of minimum?–Flexible based on sunny/cloudy weather?

Average temp: 22.6, 38, 37.5., 37.9. Total of hourly differences in temp vs unheated: 370, 358, 367.

USDA Virtual Grower – software for calculating greenhouse heating costs

77


• Use trustworthy sensors• Place sensors properly• Record regularly and reliably• Review records periodically• Recordkeeping options• By hand• Data logger

Monitoring Environment


• Thermometers, thermocouples, thermistors• Max/min thermometers and sensors• Remote data access• Internet data access• Placement• At crop level (just above)• At standard height• Watch out for shade, drafts• Protected from direct sun• Protected from heat buildup• In root zone: 2-4 inches

Temperature


Radiation Shields

Holden et al., 2013. www.fs.fed.us/rm/ubs_other/rmrs_2013_holden_z001.pdfwww.youtube.com/watch?v=LkVmJRsw5vs

http://www.fs.fed.us/rm/ubs_other/rmrs_2013_holden_z001.pdf

http://www.youtube.com/watch?v=LkVmJRsw5vs


• Hygrometer• Sensors often combined with

temperature• Observe condensation

Relative Humidity


• PAR Sensor• for plants, preferred to photometer or

pyranometer• Instantaneous measurement• Daily Light Integral (DLI)• Placement• Just above crop• Avoid shade• Level

Light

Logger and solar panel at EP

Solar Radiation and Air Temp. Sensors at RR

Light (PAR) Air Temp., and Soil

Moisture Sensors at CB

78

Example output Tinyurl.com/ppacht1Tinyurl.com/ppacht2


tinyurl.com/ppacht1tinyurl.com/ppacht2

Output from Hobo datalogger and sensors

(sensors not currently in correct position)


Watchdog dataloggers with sensors

www.specmeters.com

The system we use is downloaded manually by connecting to computer. Proprietary software displays graphs and does some summary reports.Newer products include can include wireless data transfer.

Can view readout manually.

Button logger can monitor over period of time but not convenient to check information on a regular basis.

http://wirelesstag.net/

Wireless Sensor Tags - Info

Wireless Sensor Tag - Specs

http://wirelesstag.net/


Wireless Sensor Tags - Output

Row cover on hoops

No row cover No row cover

Row cover on hoops

No row cover

Row cover on hoops

3-Sensor Temperature and Humidity Smart Home Environment System with My AcuRite

https://www.acurite.com/shop-all.html?&sensor_measurements=111

Accurite

https://www.acurite.com/environment-system-with-temperature-and-humidity-01059.html

https://www.acurite.com/multi-sensor-thermometer-with-3-temperature-sensors.html

• Acurite www.acurite.com• Davis Instruments www.davisnet.com• Extech www.extech.com• Hobo onsetcomp.com• Lascarelectronics www.lascarelectronics.com• Meter metergroup.com• Monarch monarchinstrument.com• Spectrum Technologies, Inc. specmeters.com• Wireless Tag wirelesstag.net

Some Suppliers of Environmental Monitoring Equipment

Thislistisnotmeanttobeall-inclusive.Inclusiononthelistdoesnotindicateendorsementnordoesexclusionindicatelackofendorsement.


• Sunlight drives heat, soil is main heat sink• Vent and use row covers to manage temperature and RH• Learn the danger points (hot and cold) for your crops and conditions• Monitoring equipment available at reasonable cost, but line of sight

is a factor for wireless connections• Know what you want out of monitoring before investing money and

time• Stay informed about new materials, research on heating methods,

supplemental light

Managing and Monitoring Environment in Winter High Tunnels


Michael O’Donnell, Purdue UniversityNathan Fingerle, River Ridge Farms

Ben Hartman, Clay Bottom FarmDavid Robb, Eden Prairie Farm

Thank you!Collaborators and Funding

This project was supported by a NCR SARE Partnership Grant through sub-award H004403722 to Purdue University from USDA Award 2014-38640-22156 to the University of Minnesota. The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of the USDA or the U.S. Government.

James FarmerAnalena Bruce Indiana University, BloomingtonThis project was supported by the U.S. Department of Agriculture's (USDA) Agricultural Marketing Service through grant (SCBG-15-002). Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the USDA.

Erin A. Bluhm

Israel S. Calsoyas

Purdue University, HLA

HO-297 at edustore.purdue.edu

Horticulture & Landscape Architectureag.purdue.edu/hlaManaging the

Environment in High Tunnels for Cool

Season Vegetable Production HO-297-W

mdc.itap.purdue.edu/item.asp?Item_Number=HO-297-W

https://mdc.itap.purdue.edu/item.asp?Item_Number=HO-297-W

Documents

Winter High Tunnel Environments: Managing and …...Winter High Tunnel Environments: Managing and Monitoring Illinois Specialty Crop Conference Springfield, IL January 8, 2020 Liz