Post on 19-Oct-2020
Hughie Jones1, 2, T. Andrew Black2, Rachhpal S. Jassal2, Zoran Nesic2, Mark Stephen Johnson2, 3, Sean Smukler4, 5
1 Alexis Nakota Sioux Nation1 Biometeorology and Soil Physics Group, Faculty of Land and Food Systems, University of British Columbia, Vancouver, Canada
2 Institute for Resources, Environment and Sustainability, University of British Columbia, Vancouver, Canada3 Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, Canada
4 Sustainable Agricultural Landscapes Lab, Faculty of Land and Food Systems, University of British Columbia, Vancouver, Canada5 Centre for Sustainable Food Systems, University of British Columbia
The microclimate of plastic mulches and low tunnels
Certified Organic Associations of BC Conference 2019February 22 - 24, 2019
Biometeorology and Soil Physics Group
Biometeorology studies how climate impacts the well-being of plants and animals.
Biometeorologists seek to understand the impact of climate on the balance of inputs and outputs in agricultural, forest and aquatic ecosystems.
• Radiation Balance• Carbon balance • Water balance
1. How do plastic film mulches impact radiation balance and soil heating or cooling?
2. How do low tunnels impact radiation balance, crop microclimate and productivity?
Plastic mulches andlow tunnels
3000
2300
1600 (mm)
900
200
AnnualPrecipitation
Cropthorne Farm
Mackin Creek Farm
UBC Farm
3 organic farms
Study sites
Sites: Experimentaltimeline
3 certified organic farms
Mackin Creek Farm (Near Soda Creek, BC) Owner: Robert Borsato and Catherine Allen 2016 - Lettuce and Spinach mix2017 - Broccoli
UBC Farm (Vancouver, BC)2015 - Experiment #1 (Plastic film mulches)2016 - Experiment #2 (Vegetated-free low tunnels)2017 - Experiment #3 (Vegetated low tunnels)
Cropthorne Farm (Westham Island near Ladner, BC)Owner: Lydia Ryall2015 - Melons2016 - Zucchinni
UBC Farm Plastic film mulches
Mulches are protective covers placed on the soil surface.
Like mineral and organic mulches, plastic mulch has the potential to alter:
• Soil erosion• Weed growth• Soil temperature (Ts)• Soil moisture (changes in soil evaporation, protection from rainfall)• Greenhouse gas emissions• Crop productivity
But, unlike “thick” mineral or organic mulches, plastic film mulches arethin allowing them to have unique radiative properties!
Plastic films in agriculture
Three radiation bands can be manipulated
using plastic films
Longwave (Far IR, L)
PAR/visible
Shortwave (i.e., Solar, S)
We can determine the film radiative characteristics:
• Reflectivity
• Transmissivity
• Absorptivity
Wavelength (nm)500 3000 10000
Sd Ld
Su Lu
Radiation balance
Net radiation (Rn) is the sum of incoming and outgoing radiation at the surface.
Rn = (Sd + Ld) - (Su + Lu)
Net radiometer
Incoming shortwave
Outgoing shortwave
Incoming longwave
Outgoing longwave
Net = (inputs) - (outputs)
Plastic film mulches
BE2 RD C BEP
S4 WB TMX IRT100
GN BW
Plastic film mulches
Plastic mulch
abbreviation
Shortwave
Reflectivity Transmissivity Absorptivity
BW 0.05 0.00 0.94
TMX 0.05 0.82 0.14
WB 0.45 0.00 0.55
C (bare soil) 0.17 0 0.93
Black
Clear
White
Plastic film mulches radiative properties
Plastic film mulches
July 23, 2015 July 24, 2015
UBC Farm: Low tunnels
Plastic cover
name
Plastic cover
abbreviation
Shortwave
(Sunlight)
transmissivity
Longwave
(Thermal)
transmissivity
Perforated
polyethylenePOLYperf High High
Polyethylene POLY High Medium
Thermax TMX HighLow
(glass-like)
Control No cover - -
Low tunnels
POLYperf
POLY
UBC Farm
TMXNLT
UBC Farm
Unvegetated low tunnels
Mulch temperature (Tm)
Cover temperature (Tc)
Radiation balance of low tunnels: Daytime
~75% of heating “Wind effect”
Sd Ld
Ldin Ldw
Lu
Sdin
Su “Thermal effect” (i.e., Ldw)~25% of heating
Will improve daytime heating efficiency
Radiation balance of low tunnels: Nighttime
“Wind effect” = ~75% of heating
Ld
Ld in Ldw
Lu “Thermal effect” (i.e., Ldw)~25% of heating
Will improve nighttime heating efficiency
August 1, 2017
UBC Farm: Low tunnel air temperature
August 2, 2017
OnlineTool !
Crop productivity
Cropthorne Farm, Ladner
Photo credit: Melissa Quantz
Cropthorne Farm, May 12 2016
Nikki Lax
n = 18
POLYp
NLT
Zucchini productivity
~20% increase in yield
Mackin Creek Farm
Early broccoli productivity
Month (2016 and 2017)
NLT
POLY
Pepper measurements
1. #of peppers2. Pepper fruit mass3. Pepper height4. LAI
UBC Farm: Padrón pepper productivity
NLTpp
Padrón pepper microclimate and productivity
Increased late growing seasonproductivity
CO2 depletion
June 27, 2017
June 27, 2017
July 31, 2017
July 31, 2017
• When an air gap exists between soil and mulch Tsblack < Tsclear
• When an air gap does not exists between soil and mulch Tsblack > Tsclear
• Highly reflective plastic mulches (i.e., white) can cool soils during the midday.
• A low tunnel cover with a low thermal transmissivity can increase air temperature during the daytime and nighttime.
• Low tunnels can increase crop productivity, but the mechanisms that increases air temperature may have negative trade-offs (e.g. low CO2 and high H2O concentrations).
Conclusions
Acknowledgements
BC Farm Adaptation and Innovator Program
Brian Wang, Summer Research Assistant
Nikki Lax, Summer Research Assistant
Nick Grant, Biometeorology and Soil Physics Group
Thea Rodgers, Summer Research Assistant
Ernest Wu, Summer Research Assistant
Robert Borsato & Catherine Allen, Mackin Creek Organic Farm
Lydia Ryall, Cropthorne Organic Farm
Rickey Yada, Dean, Land and Food Systems, UBC
David Kitts, Assoc. Dean, Land and Food Systems, UBC
Amy Frye, Former Director, CSFS, UBC Farm
Tim Carter, UBC Organic Farm
Michael Millar, UBC Organic Farm
Melina Biron, UBC Greenhouse Manager
Nicholas Coops, Faculty of Forestry, UBC
Chris Osborne, Osborne Seed Company
Jacob Slosberg, Osborne Seed Company
Eric Menard, Dubois Agrinnovation
AT Films
William Dam Seeds Ltd.
Allen Dobb, Climate Action Initiative
Samantha Charlton, Climate Action Initiative
Emily MacNair, Climate Action Initiative
Alexis Nakota Sioux Nation
Thea Rodger
Questions?
hughie.jones@alumni.ubc.caErnest Wu
Nikki Lax
Brian Wang
CO2
Photosynthesis: Flux of carbon dioxide (CO2) to make sugars.
H20Evapotranspiration: Flux of water (H2O) from forest to atmosphere.
Atmosphere
Forest
Use of plastic films in agriculture
Annual production (Mt yr-1)
Global 6.5
China 1.25 (20 Mha to 50 Mha)
Europe 0.7 (0.75 Mha)
N. America 0.2 (0.22 Mha)
Other major users are: Japan, Korea, Spain
The “Plastic Sea”
Southern Spain
Espi et al (2006)
https://asterweb.jpl.nasa.gov/gallery/images/almeira.jpg
Since the 1950’s global annual production of plastic has increased from1.3 to 322 Mt yr-1 in 2016, of which ~ 6.5 Mt yr-1 is consumed inagriculture.
Area covered by mulches Plastic mulches in China Okanagan Regional District
10,000,000 ha 290,000 ha
Need alternatives that are equally good!
June 27, 2017
July 31, 2017
We install sensors to continuously measure:
Climate
• Photosynthetically active radiation
• Air temperature
• Humidity
• Pressure
• Wind speed
• Precipitation (rainfall and snow)
• Soil temperature
• Soil water content
Ecosystem-scale gas exchange/flux
• H2O flux (E, evapotranspiration)
Hybrid poplar water balance study (AB and MB)
Water Balance
(Jobbagy et al. 2004)
P ≈ E
P - Precipitation (mm)E - Evapotranspiration (mm)
E > P
E < P
Low tunnel air temperature model
Plastic mulch andlow tunnel project
How do plastic film mulches and low tunnel impact crop microclimate and productivity?
We install sensors to continuously measure:
Climate
• Photosynthetically active radiation
• Air temperature
• Humidity
• Pressure
• Wind speed
• Precipitation (rainfall and snow)
• Soil temperature
• Soil water content
Ecosystem-scale gas exchange
• Evapotranspiration
Fast-growing hybrid poplar water balance study (AB and MB)
St. Albert AB 2010 (2nd yr of growth)
2013 (5th yr)
St. Albert AB, 5th year of growth (2013)
522 mm
335 mmE
P
Low tunnels are temporary hoop-like enclosures that can be covered withvarious cover types. Very versatile and allow for quick managementdecisions.
Plastic covered enclosures have the potential to alter:
• Canopy transpiration and stomatal conductance (stomatal openness)• Vapor density• Turbulence• Air temperature in the crop canopy• Crop productivity
Low tunnels in agriculture