Phytoremediation in Agroforestry Remediation Workshop Files... · Phytoremediation in Agroforestry...
Transcript of Phytoremediation in Agroforestry Remediation Workshop Files... · Phytoremediation in Agroforestry...
Phytoremediation in Agroforestry
Damase Khasa
Centre for Forest Research and Institute for
Integrative and Systems Biology, Université
Laval, Québec Canada G1V OA6
Presented during the
Soil Remediation Workshop (With special presentation on
Nextgen sequencing), Pretoria, SA, 27 - 28 May 2014
By
Part I: Temperate /subtropical AF
systems
Part II: Potential use of Agroforestry
in phytoremediation
Outline of Presentation
AF is defined as a dynamic, ecologically based, natural
resources management system that, through the integration of
woody perennials on farms, ranches, and in other landscapes,
diversifies and increases production and promotes social,
economic, and environmental benefits for land users (Orlando
declaration, 02 July 2004).
Agroforestry practices help landowners to diversify products,
markets and farm income; improve soil and water quality;
sequester carbon, and reduce erosion, non-point source pollution
and damage due to flooding; and mitigate climate change.
Definition of AF
- Forest Farming Systems
- Windbreak Systems
- Silvopastoral Systems
- Integrated Riparian Management Systems
- Intercropping Systems
I. Temperate/subtropical Agroforestry Systems
Cultivation of blueberries in managed
forest
Quebec is the only one Canadian province experimenting this concept
Advantages:
• windbreaks
• Temperature buffer effect
• Reduction of soil erosion and flowers frost
Source: MRNF 2006
Pharmacoforestry: Cultivation of medicinal
plants
e.g., name "ginseng" is used to refer to both
American (Panax quinquefolius) and Asian or
Korean ginseng (Panax ginseng)
Herboforestry: Cultivation of ornemental, aromatic
and edible herbs
• (e.g., Ferns, Sweet Gale - Myrica Gale, Labrador
Tea, Ledum groenlandicum )
Benefits of Streambank Reforestation
- Control erosion
- Nutrient filtering
- Shading effects on streams /
modification of aquatic habitat
- Food for invertebrates
- Enhance stream denitrification
- Wood production
- Wildlife corridors
- Carbon sequestration (4-5
ODT ha y-1 biomass)
Forestry Control (without crop) AgroForestry (poplars with
soybean crop)
AFFC
OLD field with a LOW [P] content (Université Laval
research site)
8 m 8 m
Riparian buffer systems
Intercropping systems
Woodlot management/soil sanitation
short rotation woody crop (SRWC) fallow
systems
Part II: Potential use of Agroforestry in
phytoremediation
Riparian buffer Systems/Areas
•Riparian areas are parts of the landscape that are strongly influenced by water•Periodic flooding, erosion, sediment deposition, alterations by wildlife
•Agricultural operations, waste disposal, discharge of effluents, grazing, vegetation removal
Nitrogen and
Phosphorus
• N and P: two of the main nutrients
of environmental concern
• In surface water eutrophication
and groundwater
contamination
Lake Winnipeg
Types of Ag
BMPs
Mitigative
BMPs
Constructed wetlands and ponds
Cover crops
Tailwater treatment
Grassed waterways
Vegetative ditches
Vegetative filter strips (VFS)
Field borders / margins
Contour strips
Windbreaks / HedgerowsVegetative
buffers
Riparian buffers
Vegetative
waterways
Edge-of-field
buffers
Conservation tillage
Polyacrylamide (PAM)
Landguard
Smart sprayer technology
Preventative
BMPs
Integrated Pest Management (IPM)
Proper pesticide mixing and loading
Pesticide reformulation
Fertilizer/pesticide
application
management
Monitoring soil nutrient level
Source: Zhang 2009
Riparian buffer
Hillside contour
Hedgerow field-border
Vegetative filter strip
Windbreak
Grassed Waterway Vegetated ditch
Tailwater pond
PAM
Main functions: Slow runoff, Increase infiltration, Trap pollutants (Zhang 2009)
Figure 3. The traditional three zone riparian buffer.
Source: Reprinted, with permission, from Schultz et al. (2000). © ˜2000 by American Society of Agronomy
Riparian buffers
Multi-species vegetation established at the interface between
croplands and surface-water to remove sediments and chemical
pollutants in run-off and shallow water from agricultural land.
• Filtration zone for streams and lakes
• Effective in controlling run-off erosion
• Preserve biodiversity (wildlife & aquatic species)
• The success of riparian buffers for phytoremediation depends on
the species used
• Examples
1. Poplars and forage grasses in multi-species buffer zones phytoremediate
atrazine and phosphorus (Chang et al. 2005; Lin et al. 2008; Kovar and
Claassen, 2009).
2. Willow cultivars tend to promote some bacterial groups and early
ectomycorrhizal species (Pezizomycetes, Sphaerosporella brunnea) in
hydrocarbons (HC) contaminated soils (Bell, Hassan et al.2014).
3. Panicum virgatum L. a grass that is grown on riparian buffer systems has a
good potential to uptake, degrade and detoxify atrazine in the rhizosphere
(Lin et al., 2008).
4. Tree species in riparian buffer zones in Peninsular Malaysia produced a
large amount of woody biomass and substantially removed sediments in
channels leading into headwater streams (Gomi et al. 2006).
5. Bamboo ( Bambusa vulgaris), a non-timber forest product valued in
handicraft, is grown in tropical riparian zones.
Riparian buffers
Riparian buffers
The phytoremediation property of vegetative grasses involves many
processes (Lin et al. 2005; Dosskey et al. 2010) :
–Soil microbial activities for herbicide degradation
–Denitrification of groundwater
–Phytostabilisation, phytoextraction, rhizodegradation
–Nutrient uptake by fast-growing species.
Short-rotation woody crop woodlot
system or soil sanitation fallow
Utilization of fast-growing trees with metal-extraction potential
including poplars, eucalypts, bamboos and N-fixing trees to
remediate contaminated soils.
• Ameliorate degraded soils
• Extract and accumulate contaminants (only at low level)
• Can create soil water deficit
• Examples
Short-rotation woody crop
system
1. Poplars and eucalypts
• Poplar-based agroforestry systems are common in India (Das and
Chatuverdi, 2005).
• Eucalypts are used as fast-growing shade trees in coffee
plantations in the tropics (Schaller et al. 2003).
• Eucalyptus spp. and Populus spp. that are cultivated at close
spacing for rotations of 10 years or less can be used in
phytoremediation (Rockwood et al. 2004).
2. Bamboos (presentation by Mr. Jan Van Zyl)
3. N-fixing trees such Acacias, Casuarinas, Leuacaenas
Alley cropping/intercropping
systems
1. Fast-growing nitrogen-fixing species
• Acacia angustissima, Acacia mangium, Inga edulis and Albizia sp.
are used in alley cropping in the tropics.
• Have potential for heavy-metal extraction and accumulation.
• However, less is known on the phytoremediation potential of alley
cropping.
• More work needs to be done to to identify systems that have a
large potential for phytoremediation, while providing local people
with food and other benefits.
Hydraulic lift
Plant roots can redistribute water from wet zones deeper in the soil, to
dry soil zones close to the surface in dry regions, a process known as
hydraulic lift (Richards and Caldwell 1987).
Deep roots absorb water when transpiration is high during the day,
and re-distribute the absorbed water to the rhizosphere in drier layers
when plant transpiration is low (at night). Figure.
Hydraulic lift
Phenomenon used in agroforestry for water redistribution between woody
species and crops, and to assist in phytoremediation of contaminated soils.
Rewetting the rhizosphere in the shallow soil layers :
–Keeps microbes active for biodegradation of organic chemicals in soils.
–keeps fine roots wet, which facilitates the absorption of pollutants by
roots.
–Enhances the release of chemicals, thereby facilitating their acquisition
by hyperaccumulators (or metallophytes) (Liste and White 2008).
Hydraulic lift
Examples :
–Acacia tortilis (Ludwig et al. 2003; Dhillon et al. 2008), Eucalyptus (Bafeel 2008;
Caldwell et al.1998; Hamada et al. 2003), Dalbergia sissoo, Melia azedarach,
Morus alba, poplars, Szygium cumini and Terminalia arjuna (Dhillon et
al. 2008) have been found to phytoremediate contaminated soils that
benefit from hydraulic lift.
Next steps
• Much more research is needed to understand the phytoremediation
potential of agroforestry systems especially in mining areas to secure food
security for local people
• For example:
*design agroforestry systems that minimize competition for water
while favoring hydraulic lift.
*assessment of decontamination potential of agroforestry tree and
shrub species for polluted soils.
*include phytoremediation potential in the criteria of tree selection
for introduction in agricultural landscapes
*more work should be done on the phytoremediation properties of
the association between agroforestry species and microsymbionts
on contaminated soils by either organic or inorganic compounds
AF at Université Laval
Unique in Canada !
Since 1997, formal M.Sc (48
credits including internship in tropical
or temperate AF (unique in Canada)
PhD sur mesure also possible
Within and between collaborations
(U. Moncton, U. Guelph, U.
Saskatchewan, U. Alberta, PFRA)
MOUs (CATIE, WAC, CIFOR)