Geography Internal Assessment - WordPress.com · Geography Internal Assessment Total word count – 2326 Introduction – 359 Methodology – 432 Quality and treatment of data –

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

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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


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


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


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


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


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.


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


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).


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


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.


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


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)


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


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


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


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.


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


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)


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.


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


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


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


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.


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


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?


27

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