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8/11/2019 Biogas Production in the Western Cape
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Overview
Western Cape agricultural character
What crops do we produce?
The wheat story
Measuring, modelling & monitoringproductivity
Biofuels vs food
Sustainability issues
CapeFarmMapper
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Winter RainfallWestern Cape
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Land UseWestern Cape
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Dryland vs Irrigated
It is unlikely that any mainstream biofuel will be
feasibly produced under irrigation, so this
discussion is mainly based on dryland
production.
The main dryland crop in the Western Cape is
wheat, mostly grown in various rotation
systems.
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Dryland Yield Potential
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Previous wheat areas (pre-1990s)
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Seasonal Rainfall > 300mm
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Climate trends study
Temperature increasing
Windrun decreasing
Evaporation decreasing (A-Pan)
Rainfall no clear trends
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Study on Observed Climate
ChangeTrends
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Temperature trends
Tmax
Tmin
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We have a history of variability.
1825-1829 predominance of reports of drought and
desiccation
1830-1833 flood and good rain reports predominated
1834-1843 drought reports predominate
1844-1848 wetter years
18491851 drought reports predominate
1852-1860 wetter years, particularly in the eastern parts
1872-1878
drought reports predominant 1881-1885 predominance of dry conditions
This variability in the WCape is likely to continue!!
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Our climate differs vastly from the
rest of SA
& thus our biofuels strategy will also differ vastly!
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We have a generally low rainfall.
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And mostly unfavourable soils
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Our dryland production zones
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Crop modelling
Analyses all the parameters of soil, rainfall,
temperature, radiation, and crop together to
determine crop growth & yield at a daily time
step
Can change input parameters to test multiple
scenarios
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Crop modelling &
Vulnerability analysis
Future daily climate
Scenarios (8GCMs)
Observed
daily climateHFA Data
Wheat Homogeneous Zones
Climate change scenariosSource downscaled data
Downscaled daily data (9 GCMs)
(C02 levels 20462065)
Reformat to APSIM
Test
Primary Impacts
Yield/growing season
Climatedata
Cropmodel
Soildata
GCM Data
(Select emissions scenario)
Spatial
Where? Systems?
How much? How is it performing?
Climate Daily observed climate (clean!)
Soils
Highly detailed representative soil/sper zone
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Western Cape
What crops do we produce?
Where are they produced?
We recently undertook a detailed crop census
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Africa Geospatial Forum 2013 Cape Town 20
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Limitations of ground survey
Time-consuming & intensive
Limited to (public) road access
Huge areas inaccessible from roads
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Land use mapping in the old days
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Land use mapping now
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Main crops grown in the Western Cape
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Top crops by areaRank Top Commodities Area (Ha)
1 Lucerne 398 819,6
2 Wheat 312 476,13 Planted Pastures Perennial 237 407,1
4 Small Grain Grazing 190 324,6
5 Natural grazing 109 095,1
6 Wine Grapes 108 040,9
7 Fallow 89 129,0
8 Canola 71 864,5
9 Barley 70 237,8
10 Planted Pastures 52 630,5
11 Lupine 38 468,1
12 Rooibos 35 978,1
13 Weeds 32 735,0
14 Apples 21 030,2
15 Table Grapes 12 683,5
16 Pears 11 086,3
17 Stubble 9 745,2
18 Triticale 9 289,6
19 Peaches 7 783,8
20 Oranges 7 621,4
21 Potatoes 6 705,1
22 Olives 6 164,0
23 Plums 5 762,6
24 Onions 4 719,1
25 Oats 4 210,3
C b i d l
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Crops by estimated value
per local municipality
B i l i d i h
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But agriculture is dynamicchanges
continually
Can use satellite imagery to monitor annual or
in-season changes
Coarser scale satellite imagery usually available
for free
Allows us to monitor crop & veld condition andchanges
50Africa Geospatial Forum 2013 Cape Town
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D l d h t t ti i th
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Dryland wheat rotation crops in the
Western Cape
Wheat
Barley
Lucerne/Medics/Clover
Lupins Canola
Wheat is proving to be most profitable when grownin a rotation system with minimum tillage toincrease soil carbon
Fieldwork - calibration of spatial models
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Fieldwork calibration of spatial models
& satellite imagery
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Harvesting trials yield data
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Harvesting trials yield data
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The concept of NDVI
One of various vegetation indices used to
assess plant growth, vigour and biomass from
multispectral satellite imagery
Vegetation:
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Vegetation:
Pigment in Plant Leaves (Chlorophyll)strongly absorbs visible light (0.4 to0.7 m)
Cell Structure however stronglyreflects Near-IR (0.7 1.1 m)
Thanks to Robin Weeks
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(courtesy http://earthobservatory.nasa.gov)
NDVI
MODIS NDVI derived dryland
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MODIS NDVI - derived dryland
production mapping
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Fieldwork - calibration of
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Africa Geospatial Forum 2013 Cape Town 60
Fieldwork calibration ofour NDVI drought maps
Satellite Image for NDVI
http://rapidfire.sci.gsfc.nasa.gov/subsets/?project=fas&subset=FAS_SouthAfrica2.2011051.terra.721.500m.jpghttp://rapidfire.sci.gsfc.nasa.gov/subsets/?project=fas&subset=FAS_SouthAfrica2.2011051.terra.721.500m.jpg8/11/2019 Biogas Production in the Western Cape
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Satellite Image for NDVI
Summer
Satellite image for NDVI
http://rapidfire.sci.gsfc.nasa.gov/subsets/?project=fas&subset=FAS_SouthAfrica2.2011051.terra.721.500m.jpghttp://rapidfire.sci.gsfc.nasa.gov/subsets/?project=fas&subset=FAS_SouthAfrica2.2011051.terra.721.500m.jpghttp://rapidfire.sci.gsfc.nasa.gov/subsets/?project=fas&subset=FAS_SouthAfrica2.2011051.terra.721.500m.jpghttp://rapidfire.sci.gsfc.nasa.gov/subsets/?project=fas&subset=FAS_SouthAfrica2.2010231.terra.721.500m.jpghttp://rapidfire.sci.gsfc.nasa.gov/subsets/?project=fas&subset=FAS_SouthAfrica2.2010231.terra.721.500m.jpg8/11/2019 Biogas Production in the Western Cape
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Satellite image for NDVIWinter
Th t f NDVI ( t )
http://rapidfire.sci.gsfc.nasa.gov/subsets/?project=fas&subset=FAS_SouthAfrica2.2010231.terra.721.500m.jpghttp://rapidfire.sci.gsfc.nasa.gov/subsets/?project=fas&subset=FAS_SouthAfrica2.2010231.terra.721.500m.jpghttp://rapidfire.sci.gsfc.nasa.gov/subsets/?project=fas&subset=FAS_SouthAfrica2.2010231.terra.721.500m.jpg8/11/2019 Biogas Production in the Western Cape
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The concept of NDVI (cont.)NDVI images are processed for every 10 or 16 days using
Maximum Value Compositing to minimise atmospheric effects
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In-season monitoring using pixel
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In season monitoring using pixel
values of NDVI
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Current season (2012)
vs 12 year mean at
Langgewens
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In-season monitoring
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2003 drought season
vs 12 year mean at
Eendekuil
SA & Western Cape dryland wheat
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SA & Western Cape dryland wheat
production
The impact of deregulation, circa 1996:
Wheat production (t/ha) and area
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0
500
1000
1500
2000
2500
3000
3500
4000
500
700
900
1100
1300
1500
1700
1900
2100
2300
Thousand
ton
Thousandha
South Africa wheat area planted South Africa wheat production Linear (South Africa wheat production)
Wheat production (t/ha) and area
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400
600
800
1000
1200
1400
1600
DUISEND
HA/T
HOUSAND
HA
JARE/YEARS
TOTALE OPPERVLAKTE ONDER KORING/TOTAL AREA PLANTED TO WHEAT
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0.0
500.0
1000.0
1500.0
2000.0
2500.0
3000.0
Thousandtons
Production Year
Production of wheat in South Africa
Noordwes/North West
Gauteng
Limpopo
Mpumalanga
Kwazulu-Natal
Vrystaat/Free State
Oos-Kaap/E. Cape
Noord-Kaap/N. Cape
Wes-Kaap/W. Cape
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0.0
500.0
1000.0
1500.0
2000.0
2500.0
3000.0
0.0
200.0
400.0
600.0
800.0
1000.0
1200.0
1400.0
1600.0
Ton
DuisendHektare
KORING: OPPERVLAKTE, PRODUKSIE EN INVOERE
Oppervlakte (ha) Produksie (ton) Invoere (ton)
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1.00
1.50
2.00
2.50
3.00
3.50
T/HA
JARE / YEARS
TOTALE GEMIDDELDE OPBRENGS VAN KORING / TOTAL AVERAGE YIELD OF WHEAT
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0%
10%
20%
30%
40%
50%
60%
0
200
400
600
800
1000
1200
1400
1600
2006/07 2007/08 2008/09 2009/10 2010/11*
%
Duisen
dton
Wheat: Percentage imports of RSA consumptionInvoere / Imports % invoere t.o.v RSA verbruik/ % imported of RSA consumption
So many old wheat fields were abandoned.
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y
M i l l d
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Marginal land
Land owners select land use according to optimalreturns
Marginal land will remain as such unless energy cropscan be produced at a lower real cost on marginal land
than on productive landsubsidies? Wheatunpopular transport differential imposed on
WCape wheat farmers
Barleyuncertain market
Canolalimited market, some potential
Triticalean alternative to wheat, fair potential
S ti l f ibilit d lli
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Spatial feasibility modelling
S ti l f ibilit d lli ( t)
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Spatial feasibility modelling (cont)
M i l l d il & t i bilit
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Marginal land - soils & sustainability
Western cape soils generally shallow andnutritionally poor (low organic C)
Conservation agriculture essential for
sustainabilityjudiciously applied canameliorate soils
Biofuels must not mine soils so residues
should be retaineda hidden cost of 2ndgenbiofuels?
Current thinking on biofuel options for
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g p
the Western Cape
Triticalebio-ethanol Canolabiodiesel
Straw/residues should be retained in soil
Rotate grain/oilseed with legumefor soilamelioration and animal fodder component
Trials to be implemented from 2015 to test theperformance of biofuels in the rotation
Economics??
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Biofuels vs food debateas it may
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y
apply to the Western Cape
Much more wheat/food could be produced in
the Western Capebut cheaper to import
than to farm marginal land.
(We are food secure as a result of favourable balanceof payments. So far)
Yet the Western Cape is now the main wheatproducing region in SA
Biofuels vs food debateas it may
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Perhaps the argument should be that by
sustainableproduction of biofuels we can
ensure that the land resource retains (and
even improves) its latent capacity to revert to
food production if ever necessary
With government supportbiofuels may
improve rural economy/jobs
apply to the Western Cape (cont)
Conclusion
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Conclusion
We have looked at:
What we have currently in terms of agricultural crops
How we measure and monitor our crops
The tenuous resources (climate and soil) which
support our dryland cropping, and climatic trends
The decline in wheat area and resulting (so-called)
marginal land
Some possible biofuels development pathwaysinthe dryland (wheat, etc.) rotation context
Cape Farm Mapperwww.elsenburg.com/gis/apps/cfm
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Cape Farm Mapper
Agricultural SpatialInformation Viewer
Farm finder/SG Codefinder
Overlaysclimate etc.
Will soon include 2013
crop survey
Basic mapping/area
calculation
Integrated data perfarm portion
Import/Export
95
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