Biogas Production in the Western Cape

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
http://earthobservatory.nasa.gov/http://earthobservatory.nasa.gov/


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MODIS NDVI - derived dryland

production mapping

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Fieldwork - calibration of


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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.jpg


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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.jpg


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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.jpg


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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


Current season (2012)

vs 12 year mean at

Langgewens


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In-season monitoring


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

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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

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1000

1200

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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

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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

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Ton

DuisendHektare

KORING: OPPERVLAKTE, PRODUKSIE EN INVOERE

Oppervlakte (ha) Produksie (ton) Invoere (ton)


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2.00

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3.00

3.50

T/HA

JARE / YEARS

TOTALE GEMIDDELDE OPBRENGS VAN KORING / TOTAL AVERAGE YIELD OF WHEAT


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0%

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30%

40%

50%

60%

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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

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Documents

Biogas Production in the Western Cape