1
What impact does shifting cultivation have
on the quality of soils in Mae Ai region
Thailand?
(Evans, 2016)
Geography Internal Assessment
Total word count – 2326
Introduction – 359
Methodology – 432
Quality and treatment of data – 1159
Conclusion – 95
Evaluation – 281
ALL RIGHTS BELONG TO OWNERTAKEN FROM WWW.INTERNALASSESSMENTS.WORDPRESS.COM
2
Table of Contents
Introduction ................................................................................. 5
Fieldwork question ...................................................................... 5
Geographical context.................................................................. 5 Situation ................................................................................................ 5
Climate ................................................................................................. 7
Background information ....................................................................... 7
Link to syllabus .......................................................................... 7
Hypothesis ................................................................................ 7
Null hypothesis ...................................................................................... 7
Prediction and Theory ................................................................ 7
Methodology ............................................................................. 10
Sites ......................................................................................... 10
Herb cover ................................................................................ 12
Infiltration rate .......................................................................... 12
Soil sample ............................................................................... 13
Soil texture ............................................................................... 13
Soil moisture ............................................................................ 14
Distribution of particle size ........................................................ 15
Tree survey grid ....................................................................... 16
Justification .............................................................................. 16
Secondary data rationale.......................................................... 17
Risk assessment ...................................................................... 17
Justification of methodology .................................................... 17
Quality and treatment of data ................................................... 18
Vegetation cover ...................................................................... 18
Infiltration rate .......................................................................... 21
Soil moisture ............................................................................ 22
Soil Particle size ....................................................................... 23
Chi square test ......................................................................... 14
Conclusion ................................................................................. 25
Evaluation ................................................................................. 25
Limitations and improvements .................................................. 25
Modification to research question ............................................. 26
Bibliography .............................................................................. 27
ALL RIGHTS BELONG TO OWNERTAKEN FROM WWW.INTERNALASSESSMENTS.WORDPRESS.COM
3
Table of Figures Figure 1 – The world map.............................................................. 5
Figure 2 – Map of Thailand showing its situation ........................... 6
Figure 3 – Map of Chiang Mai ....................................................... 6
Figure 4 – Gersmehl’s model ........................................................ 8
Figure 5 – Shifting cultivation cycle ............................................... 9
Figure 6 – Map of shifting cultivation site ..................................... 10
Figure 7 – Site of Forest .............................................................. 11
Figure 8 – Photograph showing how herb cover was taken ......... 12
Figure 9 – Photograph showing how infiltration rate was taken ... 12
Figure10 – Photograph showing how soil sample was taken ....... 13
Figure 11 – Photograph showing how soil texture was taken ...... 13
Figure 12 – Flowchart showing steps of finding soil texture ......... 14
Figure 13 – Photograph showing how soil moisture was found ... 14
Figure 14 – Photograph showing how particle size was found .... 15
Figure 15 – Soil texture diagram................................................. 15
Figure 16 – Photograph showing how tree survey was taken ...... 16
Figure 17 – Photograph showing obstruction with transect line ... 19
Figure 18 – Photograph showing possible man-made path ......... 19
ALL RIGHTS BELONG TO OWNERTAKEN FROM WWW.INTERNALASSESSMENTS.WORDPRESS.COM
4
Content of tables and graphs
Graph 1 – Scatter graph showing tree coverage ......................... 18
Table 2 – Showing herb and scrub cover of agricultural land ...... 20
Table 3 – Showing herb and shrub cover forest .......................... 20
Graph 4 – Bar graph comparing the infiltration rate ..................... 21
Graph 5 – Pie chart showing soil moisture in forest ..................... 22
Graph 6 – Radar graph showing soil particle and size ................. 23
Table 7 – Table showing the chi square test for the soils ............ 24
Table 8 – Critical values table ..................................................... 24
ALL RIGHTS BELONG TO OWNERTAKEN FROM WWW.INTERNALASSESSMENTS.WORDPRESS.COM
5
Fieldwork Question
What impact does shifting cultivation have on the quality of soils in Mae Ai region
Thailand?
Geographical Context
Situation
Figure 1 – The World Map
Adapted from (Mapsofworld, 2010)
Chiang Mai has latitude of 18°47'N and
longitude of 98°59'E (Mapsofworld.com, 2016)
Introduction
359 words
Tropical climate as it is near
equator
ALL RIGHTS BELONG TO OWNERTAKEN FROM WWW.INTERNALASSESSMENTS.WORDPRESS.COM
6
Figure 2 – Map of Thailand showing its situation
Adapted from (Mapsofworld.com, 2014)
Figure 3 – Map of Chiang Mai
Adapted from (Chaikaew,
Tripathi and Souris, 2009)
Area of fieldwork
Capital of Thailand
Mae Ai, area of forest
and shifting cultivation
ALL RIGHTS BELONG TO OWNERTAKEN FROM WWW.INTERNALASSESSMENTS.WORDPRESS.COM
7
Climate
Chiang Mai has a dry season starting mid-March until June, rainy season from July to
October and a cool season from November to February. (WorldWeatherOnline, 2012)
Background information
In Chiang Mai, Thailand, many ethnic groups depend on shifting cultivation for their
food and livelihood. Most of the ethnic groups, who practise shifting cultivation,
usually do it on the hills around the valley and are called Hill Tribes (1stopchiangmai,
2004). Shifting cultivation has been practised in the northern part of Thailand for
many years, however since the 1950s; Thailand reached stage 2 of the demographic
transition model. The population growth due to the large natural increase as well as
migration of people from Myanmar and ethic refugees from china has put large
pressure on the land.
Link to syllabus
This investigation links with syllabus “Core: Patterns in Environmental Quality and
Sustainability –Soil and change: Explain the causes of soil degradation. Discuss the
environmental and socio-economic consequences of this process, together with
management strategies.” (IBO, 2009)
Hypothesis
Shifting cultivation diminishes soil quality.
Null Hypothesis (H0)
There is no correlation between shifting cultivation and soil quality.
Prediction and Theory
To determine soil quality we would look at many different aspects of the soil such as
the moisture, type of soil, soil infiltration rate and temperature.
The soil infiltration rate is defined as the speed of water that enters the soil. Different
types of soil composition would affect the infiltration rate, to find the soil composition
we look at the particle sizes.
ALL RIGHTS BELONG TO OWNERTAKEN FROM WWW.INTERNALASSESSMENTS.WORDPRESS.COM
8
Figure 4 – Gersmehl’s model
Figure 4 shows that there is a natural nutrient cycle that happens in the forest, but
due to the nutrient that is in the crops harvested, there would be less released as the
litter decomposes.
The Universal Soil Loss Equation is a way of estimating the average annual soil
erosion.
The Universal Soil Loss Equation relates with our field study as we measured both
the land cover (trees, herb and shrub) and conservation practises (shifting cultivation)
Nutrients recycled through
dead organic matter
Some biomass loss due
to harvesting as crops
A – Predicted soil loss
R – Rainfall factor
K – Soil erodibility factor
LS – Topographic factor
C – Land cover factor
P – Conservation practices
ALL RIGHTS BELONG TO OWNERTAKEN FROM WWW.INTERNALASSESSMENTS.WORDPRESS.COM
9
Figure 5 – Shifting cultivation cycle
Adapted from J.Singh
This diagram shows the stages of shifting cultivation, showing that it’s a sustainable
form of agriculture. The sites we visited were in stage 1 (forest) and stage 5
(Abandonment and regrowth).
ALL RIGHTS BELONG TO OWNERTAKEN FROM WWW.INTERNALASSESSMENTS.WORDPRESS.COM
10
Sites
Figure 6 – map of shifting cultivation site
(Google maps, 2015)
This particular site was chosen as it is in the 5th stage of the shifting cultivation cycle,
allowing us to see the effects of shifting cultivation on the soil quality. It is also a site
that was used by the hill tribes.
Site of shifting cultivation, longitude
20.08138N and latitude 99.46833E
(Chang, 2016)
Methodology 432 words
Stage 5 of shifting cultivation
– Abandonment and
regrowth
Biomass from rice farming
ALL RIGHTS BELONG TO OWNERTAKEN FROM WWW.INTERNALASSESSMENTS.WORDPRESS.COM
11
Figure 7 – Site of Forest
(Google maps, 2015)
We chose this site as it is the 1st stage of shifting cultivation cycle, which provides us
with the comparison of soil quality before and after shifting cultivation.
(Evans, 2016)
Dead leaves from trees.
Large scrub cover .
Site of Forest, longitude 20.03544N and
latitude 99.16593E
More trees in canopy
layer.
Stage 1 – Site
selection/Primary forest.
ALL RIGHTS BELONG TO OWNERTAKEN FROM WWW.INTERNALASSESSMENTS.WORDPRESS.COM
12
Herb Cover
Figure 8 – photograph showing how herb cover was taken
(Wee, 2016)
Infiltration rate
Figure 9 – photograph showing how infiltration rate was taken
(Chew, 2016)
1. Set up a 20m transect
line
2. Place 50cmx50cm quadrat
every 5 metres
3. Calculate percentage
cover
2. Wooden hammer used to
hammer Infiltrometer in ground.
3. 1 litre of water added to
Infiltrometer.
4. Stopwatch used to time
how long water infiltrates
ground.
1. Infiltrometer is place at 0m,
10m and 20m.
Herb
s
* removed the dead leaves first before testing
infiltration
ALL RIGHTS BELONG TO OWNERTAKEN FROM WWW.INTERNALASSESSMENTS.WORDPRESS.COM
13
Soil Samples
Figure 10 – photograph showing how soil samples were taken
(Evans, 2016)
Soil texture
Figure 11 – Photograph showing how soil texture was found
1. Samples collected at
0m, 10m and 20m with
soil auger
2. Sample added to jar
Human obstruction (Metal
pipe)
1. Soil sample from all 3 groups
added together
2. Water added and steps
followed in flowchart in figure
12
(Mai, 2016)
ALL RIGHTS BELONG TO OWNERTAKEN FROM WWW.INTERNALASSESSMENTS.WORDPRESS.COM
14
Figure 12 – Flowchart showing steps of finding soil texture
(Whiting, 2016)
Soil Moisture
Figure 13 – Photograph showing how soil moisture was found
1. 100g of soil sample is place
on a tray
2. Tray placed in oven for
many hours to dry
3. Difference in before and after
mass used to determine moisture
ALL RIGHTS BELONG TO OWNERTAKEN FROM WWW.INTERNALASSESSMENTS.WORDPRESS.COM
15
Distribution of particle size
Figure 14 – Photograph showing how particle size was found
(Mai, 2016)
Figure 15 – Soil texture diagram
1. Using the particle size we
found the percentage of each
soil type.
2. Followed the diagram to find
soil texture.
(SoilSensor, 2011)
1. Dry soil sample placed in
sieves of different sizes
2. Sieve is shook to
distribute different particle
sizes
3. Each sieve container is
emptied and weighed
Forest sample
Agriculture sample
ALL RIGHTS BELONG TO OWNERTAKEN FROM WWW.INTERNALASSESSMENTS.WORDPRESS.COM
16
Tree survey grid
Figure 16 – Photograph showing how tree survey was taken
(Evans, 2016)
Justification of apparatus
Apparatus Justification
Tape measure A simple and accurate way of measuring.
Quadrant Effective way to measure percentage cover. Easy to carry around.
Sieves Accurate and easy way to separate particle size
Infiltrometer Covers a large area and can easily see if water has fully infiltrated the ground
Soil auger Collect a large quantity of soil as it goes deep, thus it allows us to get the more moist soil at the bottom.
Weighing scale Easy and accurate way of measuring mass.
5 metres
20 meters
1. We stood next to each
other with 1 metre interval
2. We then walked up 20
meters and recorded any
trees
Only trees above 1.5m were
counted
ALL RIGHTS BELONG TO OWNERTAKEN FROM WWW.INTERNALASSESSMENTS.WORDPRESS.COM
17
Secondary data rationale
When selecting my secondary data, I looked for the most reliable and relevant
sources from relevant geography textbooks and journals. I made sure that the
information linked to the syllabus.
Risk assessment
Safety precautions:
Wear appropriate footwear (proper grip), reduces chance of falling as
fieldwork is on a hill.
Applying sunblock and wearing hat to avoid sunburns.
Bringing at least 2 litres of water to prevent dehydration as temperatures
reach up to 40oC.
Applying insect repellent to avoid mosquito bites.
When working in forest, wear long sleeves and pants from protection from
thorns.
Justifications of methodology
Group sizes:
We were all in groups of 5, as it would allow us all to come to an agreeable answer if
there were any inquiries about our results, e.g. herb coverage.
Vegetation cover:
By recording vegetation cover, it would allow us to see how having vegetation will
affect the overall soil quality and link it to the other results such as infiltration and
moisture.
Infiltration Rate:
Infiltration is important as the soil composition relies greatly on whether there is a
great amount of surface runoff, which affects soil quality.
Moisture and soil composition:
The samples of soil were taken beside where the infiltration rate was taken as it
would allow us to see how infiltration has an effect on moisture. By taking samples
next to where infiltration rate was measured, it also allowed us to get the soil
composition that close to what was tested for infiltration. Also using the Soil Texture
diagram instead of the flowchart is more reliable and accurate due to the lower
chance of human error.
ALL RIGHTS BELONG TO OWNERTAKEN FROM WWW.INTERNALASSESSMENTS.WORDPRESS.COM
18
Vegetation cover
Graph 1 – Scatter graph showing the tree coverage
Graph 1 shows the tree coverage in the forested area, the forested area had a large
number of trees compared to the agriculture area which had no trees due to slash
and burn. With the large amount of tree coverage there would be a natural cycle of
nutrients from the fallen leaves and other biomass compared to the agricultural area.
The amount of tree coverage would also affect the infiltration rate, soil moisture and
soil texture.
The vegetation cover is a factor in the universal soil loss equation as the trees would
intercept the rainfall reducing the impact on the ground.
Trees also play a part in the Gersmehl’s model, without trees there would not be a
natural nutrient cycle, harming the soil quality as there would not be any humus in the
top layer of the soil.
The two circled points might be possible errors as those two are the only locations
with multiple trees in a row, possible causes are that smaller plants were mistaken as
trees.
Quality and treatment of data 1130 words
0
2
4
6
8
10
12
14
16
18
20
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Me
tre
Metres
Tree coverage
Tree
Possible errors/anomaly
Absence of
trees, explained
in figure 18
ALL RIGHTS BELONG TO OWNERTAKEN FROM WWW.INTERNALASSESSMENTS.WORDPRESS.COM
19
Figure 17 – photograph showing obstruction with transect line
(Evans, 2016)
Figure 18 – photograph showing possible man-made path
Transect line blocked by
shrubs, making it not straight
Path leading into forest
Absence of shrubs and herbs
Possible
explanation to
anomaly in tree grid
When noting down
tree, some might be
noted twice
(Evans, 2016)
ALL RIGHTS BELONG TO OWNERTAKEN FROM WWW.INTERNALASSESSMENTS.WORDPRESS.COM
20
Table 2 – showing herb and shrub cover of Agricultural land
Distance (M)
0 5 10 15 20
Herb layer (%)
4 0 2 2 0
Shrub layer (%)
2 - 3 - 1
Table 3 - Showing herb cover of Forest
Distance (M)
0 5 10 15 20
Herb layer (%)
7 2 5 2 5
Shrub layer (%)
27 - 28 4
Table 2 and 3 shows the difference in shrub and herb cover between both sites.
There is generally more coverage in the forest than the agricultural site. The shrub
and herb coverage is important in the quality of the soil as it would affect the
infiltration rate as the roots create channels that allow water to pass through, the
dead leaves from the herbs and shrubs also add to the humus in the soil. The roots
also help to anchor the soil together, thus preventing surface runoff.
There are more shrub and herb coverage in the forest than the agricultural land
because in the forest there are animals such as birds that carry the seeds of the
different plants and transport it around, also in the agricultural land it has a few herbs
as it is in the early stages of regrowth, thus there would be small amounts of plants
starting to grow back.
The anomaly in the shrub layer of the forest at the 20m mark (highlighted in yellow) is
due to there being a tree in the area that was being sampled; this made it harder to
estimate the shrub coverage within the 2m x 2m area.
The shrub and herb coverage plays a part in the universal soil loss equation as well
as the Gersmehl’s mode as it affects both the surface run off and nutrients cycle.
ALL RIGHTS BELONG TO OWNERTAKEN FROM WWW.INTERNALASSESSMENTS.WORDPRESS.COM
21
Infiltration rate and temperature
Graph 4 – Bar graph comparing the average infiltration rate and temperature
between the two sites
Graph 4 shows the difference in infiltration rate between the two sites, the graph tells
us that there is a higher infiltration rate in the forest. The reason there is a greater
infiltration rate in the forest is due to the number of trees in the area. The number of
trees would affect the infiltration rate due to the roots of the trees creating networks
called macro pores (Aubertin, 1971); this allows the water to flow through the soil
easily.
The infiltration rate would have a great effect on the soil texture and moisture as if
there is poor infiltration rate there would be large amounts of surface runoff which
would cause the nutrients of the soil to be washed away, lowering the soil quality.
For sample point 2, the infiltration rate for the agriculture site is fairly low; this could
be due to the human obstruction (metal pipe) as seen in figure 10 above.
Also, for the first sample point there is an anomaly as the infiltration rate is higher for
the agricultural site; this could have been because of not clearing the leaves properly
before doing the infiltration rate or it could also be due to the fact that the gradient for
the agriculture site was greater than forest because the hills are where most of the
shifting cultivation takes place.
The temperature for the forest is overall cooler than the agriculture site; this is
because of the lack of vegetation cover in the agriculture site which blocks direct
sunlight from shining onto the ground
29oC 27oC
26oC
33oC
35oC
36oC
0
0.1
0.2
0.3
0.4
0.5
0.6
1 2 3
Infi
ltra
tio
n r
ate
(l/
min
)
Sample points
Inflitration rates between the two areas
Forested area
Shifting Cultivation
Anomaly
ALL RIGHTS BELONG TO OWNERTAKEN FROM WWW.INTERNALASSESSMENTS.WORDPRESS.COM
22
Soil Moisture
Graph 5 – Pie chart showing soil moisture in forest
Graph 5 shows that there is a 10% difference in soil moisture between the forest and
agriculture sites. This links back to infiltration rate and tree coverage, due to the
greater infiltration rate in the forest, there is more moisture in the soil. The lack of tree
coverage would also mean that there would be more direct sunlight on the soil
evaporating the water quicker.
Due to the lack of rain and it being the “hottest it has ever been in 12 years”
(Massingham, 2016) would affect the overall soil moisture. There had not been any
rain in the month of March and only 3mm of rain in April before we took our samples,
with temperatures reaching up to 41oC (accuweather, 2016).
Moisture of the soil plays a crucial part in the quality of the soil as it helps to store
water for plants in times of drought, which there was when we took our samples. This
is the most important factor for the agricultural area as the crops grown there were
rice. The moisture is also essential to the transport of nutrients to the plants, helping
them grow.
Agriculture sample Forest sample
ALL RIGHTS BELONG TO OWNERTAKEN FROM WWW.INTERNALASSESSMENTS.WORDPRESS.COM
23
Soil particle size
Graph 6 – Radar graph showing soil particle size distribution of both sites
Graph 6 shows the different sizes of soil particles which allows us to find the soils
texture. From the graph we can see that the soil sample form the forest is mostly
made from silt (46%) and agriculture site is mostly sand (55.9%)
By following the soil texture diagram shown in figure 15, we know that the soil texture
is loam. This shows that the soil quality in the forest is of high quality as loam is rich
in nutrients, has great ability to retain moisture and humus which are all essentially in
maintaining plant growth (Brown, 2003).
Whereas the soil texture from the agricultural site is sandy loam. This comparison
shows a clear difference in soil quality which helps to prove our hypothesis. It shows
that the soil quality has diminished when the land was used for agriculture. Sandy
loam soils are unable to hold a significant amount of water and therefore require
large amounts of irrigation, therefore the irrigation used would contribute to
diminishing the soil quality further as more soil is washed away.
The crops that were grown on the agricultural land was rice, this would explain why
the soil quality diminished as rice requires a lot of water, contributing to surface runoff.
The soil texture helps to explain why there is a difference in the moisture levels as
loam can retain its moisture compared to sandy loam which can’t.
0.00%
5.00%
10.00%
15.00%
20.00%
25.00%
30.00%10
20
30
40
6080
100
250
250+
Soil particle size distribution
Agriculture
Forest
ALL RIGHTS BELONG TO OWNERTAKEN FROM WWW.INTERNALASSESSMENTS.WORDPRESS.COM
24
Chi Square Test
Table 7 – table showing the chi square test for the soils.
Chi Square Test Observed (arcsine) (Agriculture)
Expected (arcsine) (Forest)
( )
Size of Sieve
10 21.6 6.80 32.2
20 31.7 19.6 7.47
30 22.5 24.7 0.196
40 18.1 21.0 0.400
60 19.8 27.1 1.97
80 14.2 20.6 1.99
100 10.8 15.6 1.48
250 18.1 21.0 0.400
250+ 10.9 11.7 0.0547
∑ 46.2
Table 8 – Critical values
The chi square test in tables 7 and 8 tell us the chances of our hypothesis being
wrong, with our value being 46.2, it shows that out hypothesis has less than 0.1%
chance of being wrong, therefore we reject our null hypothesis and accept the
hypothesis of shifting cultivation diminishes soil quality.
Also using arcsine instead of percentage gives the values more theoretical freedom
to vary as if it was percentage, the values would be just limited to 0 to 100.
ALL RIGHTS BELONG TO OWNERTAKEN FROM WWW.INTERNALASSESSMENTS.WORDPRESS.COM
25
In conclusion, the results suggest that the hypothesis is true, shifting cultivation
diminishes soil quality.
The conclusion is supported by the results of the investigation where it shows there is
a clear difference between the soil quality of the shifting cultivation site and the forest
as we can see that the composition of soil between the agricultural site (sandy loam)
and primary forest site (loam) are different, along with the infiltration rate and
moisture. The chi square test allows us to reject the null hypothesis as it has less
than 0.1% chance of being correct.
Evaluation 281 words
Limitations and improvements
Type of survey
Possible errors Limitations Improvements
Tree survey grid
- Everyone might have a different opinion on what a “tree” is. - The transect line might not have been straight as seen in figure 17
-The results would be subjective.
- Before taking survey have a proper discussion on what a tree is.
- Have multiple people
look at the “tree”
Scrub and herb cover
-Percentage coverage is based on estimation.
-Can have large errors.
-Have multiple people estimate the percentage and come to an agreement.
Infiltration rate -Infiltrometer not properly hammered in ground.
-Infiltration timing is wrong.
- Make sure that the Infiltrometer is hammered far down enough.
Soil moisture -Small leaves might be left in the tray.
- There would not be an accurate reading of moisture.
- Try to remove as much dead leaves/organic matter if possible.
Particle size -When emptying the sieves, the small particles would be affected by the air from the fan/air conditioner. -Not able to empty the sieve fully
- The mass percentage is not accurate.
-Before weighing the different soil particles, turn off all fans/air conditioners. -Use a brush and properly bush off all the soil.
Conclusion 95 words
ALL RIGHTS BELONG TO OWNERTAKEN FROM WWW.INTERNALASSESSMENTS.WORDPRESS.COM
26
Modification of research questions
This research question allowed us to complete our investigation and come to a
suitable conclusion of soil quality decreases when land is used for shifting cultivation;
however it did not take into account of the overextended period of shifting cultivation.
Since shifting cultivation is seen to be a sustainable form of farming, there might be
another factor that is affecting the soil quality, such as the type of crops grown
Therefore the new research question would be:
How does the type of crop affect the soil quality of the land?
ALL RIGHTS BELONG TO OWNERTAKEN FROM WWW.INTERNALASSESSMENTS.WORDPRESS.COM
27
Bibliography Agriculturesnetwork.org. (2013). 1.3.1 Importance of soil moisture — AgriCultures
Network. [online] Available at:
http://www.agriculturesnetwork.org/resources/learning/mod2-online/learning-block-
1/1.3/1.3.1 [Accessed 16 May 2016].
Aubertin, Gerald M. (1971). Nature and extent of macropores in forest soils and their
influence on subsurface water movement. Res. Pap. NE-192. Upper Darby, PA: U.S.
Department of Agriculture, Forest Service, Northeastern Forest Experiment Station.
33 p.
BOND, W. and COLLIS-GEORGE, N. (1981). PONDED INFILTRATION INTO
SIMPLE SOIL SYSTEMS. Soil Science, 131(6), pp.327-333.
Brian Massingham
Chaikaew, N., Tripathi, N. and Souris, M. (2009). Exploring spatial patterns and
hotspots of diarrhea in Chiang Mai, Thailand. International Journal of Health
Geographics, 8(1), p.36.
Cherie, N. (2012). Geography: Shifting cultivation. [online]
Thestudyofearth.blogspot.sg. Available at:
http://thestudyofearth.blogspot.sg/2012/03/shifting-cultivation.html [Accessed 23 Apr.
2016].
David Whiting, C. (2016). Estimating Soil Texture: Sand, Silt or Clayey. [online]
Ext.colostate.edu. Available at:
http://www.ext.colostate.edu/mg/Gardennotes/214.html [Accessed 6 May 2016]
Doran, J. and Jones, A. (1996). Methods for assessing soil quality. Madison, Wis.,
USA: Soil Science Society of America.
Ibgeog2009.wikispaces.com. (2009). IB Geography 2009 Wiki -
Environmental_Quality_Sustainability_Patterns. [online] Available at:
http://ibgeog2009.wikispaces.com/Environmental_Quality_Sustainability_Patterns
[Accessed 6 May 2016].
IBO 2009. Geography Guide First examinations 2011, International Baccalaureate.
International Work Group for Indigenous Affairs (IWGIA). (2014). Shifting Cultivation,
Livelihood and Food Security New and Old Challenges for Indigenous Peoples in
Asia. [online] Available at: http://www.iwgia.org/publications/search-
pubs?publication_id=694 [Accessed 23 Apr. 2016].
Kellogg, C. (1962). The Soil under Shifting Cultivation. Agronomy Journal, 54(3),
p.279.
Mapsofworld.com. (2014). Physical Map of Thailand. [online] Available at:
http://www.mapsofworld.com/physical-map/thailand.html [Accessed 23 Apr. 2016].
ALL RIGHTS BELONG TO OWNERTAKEN FROM WWW.INTERNALASSESSMENTS.WORDPRESS.COM
28
Emapsworld.com. (n.d.). Thailand Location Map | Location Map of Thailand. [online]
Available at: http://www.emapsworld.com/thailand-location-map.html [Accessed 23
Apr. 2016].
Mapsofworld.com. (2016). Thailand Latitude and Longitude Map. [online] Available at:
http://www.mapsofworld.com/lat_long/thailand-lat-long.html [Accessed 6 May 2016].
R. B. Brown (2003). "Soil Texture". Fact Sheet SL-29. University of Florida, Institute
of Food and Agricultural Sciences.
Schittich C (2001). Building Simply. Birkhäuser Architecture. pp. 38–42.
Shanstrom, N. (2014). Tree Roots Improve Soil Infiltration Rates | DeepRoot Blog.
[online] Deeproot.com. Available at: http://www.deeproot.com/blog/blog-entries/how-
trees-affect-soil-infiltration-rates [Accessed 16 May 2016].
Soilmoisturemeasurement.co.uk. (n.d.). Soil Moisture Measurement | Why do we
need to know the soil moisture content of soil?. [online] Available at:
http://www.soilmoisturemeasurement.co.uk/news/why-do-we-need-to-know-the-soil-
moisture-content-of-soil/ [Accessed 16 May 2016].
Soilsensor.com. (2011). SoilSensor.com: Soil Types. [online] Available at:
http://www.soilsensor.com/soiltypes.aspx [Accessed 16 May 2016].
Water.usgs.gov. (2012). Infiltration - The Water Cycle, from USGS Water-Science
School. [online] Available at: http://water.usgs.gov/edu/watercycleinfiltration.html
[Accessed 16 May 2016].
ALL RIGHTS BELONG TO OWNERTAKEN FROM WWW.INTERNALASSESSMENTS.WORDPRESS.COM