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Geographia Technica, Vol. 17, Issue, 2, pp 208 to 219
MAPPING OF
SUBAK AREA
BOUNDARIES AND SOIL FERTILITY
FOR AGRICULTURAL LAND CONSERVATION
Ida Bagus Putu BHAYUNAGIRI
1
*and Moh SAIFULLOH 2
DOI: 10.21163/GT_2022.172.17
ABSTRACT:
Soil fertility is the most crucial aspect of the sustainability of agricultural land productivity. As an
agricultural country, Indonesia is closely related to agricultural activities and soil fertility. This
scientific paper analyzed the boundary of subak, soil fertility condition, which will later be used as a
guide for agriculture land conservation. Subak is a traditional Balinese farmer organization that aims
to manage water irrigation and rice cropping patterns in paddy fields. Boundary subak agricultural land
is determined by participatory mapping method, involving farmers. Soil fertility data were analyzed
through field and laboratory surveys. The condition of the limiting factors for soil fertility in each
mapping unit is then used as the basis for managing and conserving agricultural land. The result showed
that area of subak in agriculture land is 2,177.33 ha divided into 65 Subaks. Soil fertility status in each
Subak is grouped into two soil fertility statuses (medium and high). Therefore, it is necessary to carry
out integrated soil conservation, such as returning plant residues into the soil periodically and adding
organic matter and fertilizers containing P and K elements in single fertilizers and compound fertilizers.
Adding P and K compound fertilizers is needed to support optimal land productivity and increase the
CEC value of the soil. Types of organic matter can be applied to the soil by returning crop residues,
manure, and composting.
Key-words: GIS, Conservation, Mapping, Soil Fertility, Subak, Bali-Indonesia.
1. INTRODUCTION
Subak is a traditional Balinese farmer organization that primarily aims to manage water irrigation
and rice cropping patterns in paddy fields (Sumiyati et al., 2017; W. Windia et al., 2018). Subak is a
traditional organization that is already known abroad. As an organization that deals with conventional
irrigation systems, Subak also has a unique attraction for tourists, namely terraced rice fields,
generally composed of terraced rice fields or terraces resembling unsized steps; this view presents
tourists with both local and local. Furthermore, foreign countries visit Bali (Suasih et al., 2018).
United Nations Education, Scientific, and Cultural Organization (UNESCO), on June 12, 2012,
designated Subak as a world cultural heritage in the cultural landscape category.
One of the challenges currently facing Subak is the shrinking of irrigated paddy fields due to
conversion to non-agricultural activities. In the last five years, rice fields in Bali have decreased by
more than 1000 ha/year (Windia & Wiguna, 2013). Land conversion occurs in many urban areas
because it is triggered by land prices that continue to soar, so farmers in urban areas are very tempted
by very high price offers. The land-use change is thought to be due to the low productivity of
agricultural land, one of which occurred in Subak in Sawan District, Buleleng Regency, Bali-
Indonesia Province.
In agriculture, especially in plant cultivation, soil conditions and their management are essential
factors determining whether the growth and yield of plants to be cultivated are optimal. This is
because the soil is a production factor that acts as a growing medium for plants, a supplier of nutrients,
and a water supply indispensable for plant growth (Subedi, 2018). Therefore, the ability of the soil to
support plant growth will be determined by the state of soil fertility. As far as fertility is concerned,
soil productivity can be improved and enhanced by specific technological inputs.
1
*Land Resources Laboratory, Faculty of Agriculture Udayana University, 80234 Denpasar, Indonesia,
Corresponding author*, bhayunagiri@unud.ac.id
2 Spatial Data Infrastructure Development Center Udayana University, 80234 Denpasar, Indonesia,
moh9saifulloh@gmail.com
209
Soil fertility is the ability of the ground to provide balanced amounts of nutrients for plant growth
and production. Planting crops can cause the loss of essential nutrients in the soil because, during
harvesting, essential nutrients are transported out of the land, mainly if they are cultivated
continuously (Kome et al., 2019; Bayu, 2020; Prabakaran et al., 2021). Thus, soil fertility will
decrease until it reaches a state where the addition of nutrients through fertilization is necessary to
obtain profitable agricultural products.
The boundaries of the subak agricultural area are not currently available spatially. The data is
essential, especially in the management of subak agricultural land, irrigation arrangements, and the
distribution of fertilizer subsidies by the government so that they are right on target and in the right
location. Subak land mapping and quantification of soil properties were carried out using a
Geographic Information System (GIS). Previous researchers used GIS technology to map landslide
hazards (Diara et al., 2022; Trigunasih & Saifulloh (a), 2022), monitor changes in vegetation index
and urban air quality (Sunarta & Saifulloh, 2022), as well as spatial analysis of relationships between
flooding and soil infiltration in urban areas (Trigunasih & Saifulloh (b), 2022). We use GIS to analyze
and map the spatial distribution of agricultural subaks, and soil properties, which are used as the basis
for future subak land conservation.
Evaluation of fertility status to assess and monitor soil fertility is essential to identify deficiencies
or obstacles in terms of nutrients possessed by the land. One way that is often used to assess the soil's
fertility is through soil analysis or soil testing. Soil analysis or testing is a relatively more objective
approach to determining soil fertility status. Assessment of soil fertility status is essential because if
no fertilization action is under the soil's needs over time and land use, then soil fertility will decrease.
This research was conducted to know the spatial distribution of Subak land, analyze soil fertility
status, and provide recommendations for land conservation based on soil fertility properties.
2. STUDY AREA
The case study of this research is administratively located in Sawan District, Buleleng Regency,
Bali, Indonesia. Geographically, Sawan Regency is located at 8° 5' 14" - 8° 14' 45" South Latitude
and 115° 6' 55' - 115° 11' 1" East Longitude (Fig. 1). This is because it has varied topography and
slopes. Subak agriculture stretches widely from the upstream area with an altitude of > 2000 m asl to
the northern coastal area with an altitude of < 5 m asl. The slope of the slope also varies, from flat (0-
8%) to very steep (> 45%). Rainfall in the upstream area reaches > 2500 mm/yr, while in coastal
areas, it ranges from 1000-1500 mm/yr.
Fig.1. The research location is viewed from a low scale (left, a and b),
the research location appears to be on a larger scale (right).
Ida Bagus Putu BHAYUNAGIRI and Moh SAIFULLOH / MAPPING OF SUBAK AREA BOUNDARIES … 210
The subak area in this study focuses on wetlands ie rice fields. Based on field observations, the
period of the rice cropping pattern on the land is 2 times a year, depending on the conditions of the
availability of rainwater and irrigation. This condition is assumed to affect the chemical variability
and soil fertility of subak agricultural land. On steep slopes to steep, it was easily leaching nutrients
due to being washed away by rainwater in the upstream to downstream areas.
3. DATA AND METHODS
3.1. Tools and Materials
The materials used to analyze soil samples in the laboratory are chemical substances as reagents
for soil analysis. The materials used for analysis in the laboratory include HCl 25%, NH4OAc pH 7
1N, 80% alcohol, 50% NaOH, concentrated H2SO4, liquid paraffin, concentrated H3PO4, K2Cr2O7,
FeSO4 1N, DPA, Whatman 42 filter paper, an indicator of methyl red and aqua dust. The maps are
the image of the research area from Google Earth in 2020, a slope map, a land map, subak map. The
tools needed in this research are: tools in the laboratory include an oven, pH meter, Erlenmeyer,
pipette, burette, Kjeldahl flask, and Kjeldahl distillation device. The tools needed in the field include
a Belgian drill, dagger, meter, plastic bag, label paper, Garmin Montana 6.80 Hand GPS and
stationery.
3.2. Methods and stages of research
This research was conducted using survey methods and soil test methods which were analyzed at
the Laboratory of Soil and Environmental Sciences, Faculty of Agriculture, Udayana University. The
chemical properties of the soil determined were Cation Exchange Capacity (CEC) and Base
Saturation (NH4OAc Extraction pH 7 1N), total P2O5 and total K2O content (25% HCl), C-Organic
content (Walkley and Black, 1934), pH (H2O 1: 2.5), then the levels are determined based on the
criteria for soil chemical properties (PPT, 1995). Determination of soil fertility status using technical
instructions for evaluation of soil fertility-Indonesia (PPT, 1995). The criteria for assessing soil
chemical properties are presented in Table 1.
Table 1.
Criteria of several chemical properties of the soil.
Criteria
Very Low
Low
Moderate
High
Very High
C Organic (%)
< 1.00
1.01-2.00
2.01-3.00
3.01-5.0
>5.00
P2O5 Bray I (ppm)
< 10
10-15
16-25
26-35
>35
P2O5 (ppm), Olsen,
1954
< 10
10-25
26-45
46-60
>60
K2O (me/100 g)
< 0.1
0.1-0.2
0.3-0.5
0.6-1.0
>10
Base Saturation (%)
< 20
20-35
36-50
51-70
>70
CEC (me/100 g)
< 5
5-16
17-24
25-40
>40
pH
4.5-5.5
Sour
5.6-6.5
Bit Sour
6.6-7.5
Netral
7.6-8.5
Bit Base
>8.5
Alkaline/base
The stages of the research started with delineating the mapping unit, field survey, and soil analysis
in the laboratory. Delineation of mapping units based on land map overlays, slope maps, and subak
maps. Determination of subak boundaries is done by participatory mapping, involving farmer groups
who own the land. Farmers have a main role in this activity, while researchers are GIS operators who
direct the mapping of the boundaries of the subak area. From the results of overlaying several maps,
a map of the mapping unit can be obtained, which is used as an observation unit in soil sampling.
Making a unit mapping using a QGIS 3.22 LTR applications. The spatial distribution of mapping
units is presented in the next sub-chapter. Field surveys are carried out by checking the correctness of
the boundaries of the mapping unit, then adjusting to the conditions in the field. Furthermore, soil
211
samples were taken with a depth of 0-30 cm in the mapping unit following the irrigation canal from
upstream, middle, and downstream with a purposive sampling method and then composited. A
Belgian drill and GPS assisted this soil sampling for geo-tagging the location.
Soil analysis in the laboratory was carried out after taking soil samples in the field. The chemical
properties of the soil analyzed included pH, CEC, Base Saturation, K-total, P-total, and C-organic.
The results of soil analysis are used to assess soil fertility status. After obtaining soil chemical
properties data, tabulated using the QGIS 3.22 LTR application by entering soil chemical properties
data into a table to make it easier to view soil chemical properties data and determine soil fertility
status. Evaluation of fertility status is determined based on the chemical properties of the soil, which
is matched with the criteria for soil fertility status (PPT, 1995). Determination of land conservation
based on soil fertility status and limiting factors on low and medium soil fertility. After obtaining the
results of laboratory analysis, a determination is made by classifying the status of soil fertility
according to the criteria for assessing chemical properties (Sardiana et al., 2017; Siregar et al., 2021).
4. RESULTS AND DISCUSSIONS
4.1. Mapping of Subak Land
Subak is a community organization that regulates the irrigation system used in rice cultivation
in Bali, Indonesia. Subak generally has a temple called Pura Uluncarik or Pura Bedugul, specially
built by landowners and farmers. According to Balinese beliefs, the temple is dedicated to Dewi Sri,
the goddess of prosperity and fertility. This irrigation system is managed by a traditional leader
(Pekaseh), a farmer in Bali. The subak system has become one of the characteristics of Balinese
society. This irrigation system develops under the influence of solid Hindu religious values . It forms
a pearl of local wisdom, which allows farming communities in Bali to be in harmony with nature to
obtain optimal yields (Windia & Wiguna, 2013). Based on the participatory mapping, the area of
Subak land in Sawan District is 2,177.33 ha, which is divided into 65 Subaks. Subak with an area of
75-100 ha, there are 4 Subaks, including the Landahan Kerobokan, Guliang and Babakan Jagarag.
Subak above 100 ha there is only one Subak, namely Kloncing with an area of 102.24 ha. The graph
of the difference in the area of Subak from the mapping is presented in Fig. 2.
Fig. 2. The graph of the difference in the area from the mapping of Subak.
25.29
35.00
50.92
96.61 75.95 49.75 9.26
60.48
56.00 23.34
35.00 16.71
12.00
12.34
74.00 7.53
21.43
35.08 4.25
65.09 36.19
56.38 9.28
22.31 6.18
10.18
16.36
16.48
79.16 16.00
17.27
102.24 44.83
38.67 8.00
75.00
76.00 51.63
43.43 5.07
57.01 32.54 16.22
11.70
22.74
66.67 24.84 11.62
9.50
10.91
5.86
30.33
65.48 9.68
11.30
33.02 19.03
27.26 8.91
15.17
22.09
30.69
29.75
50.32
58.00
-
20.00
40.00
60.00
80.00
100.00
120.00
Area (ha)
Subak in Sukasada District, Buleleng, Bali-Indonesia
Ida Bagus Putu BHAYUNAGIRI and Moh SAIFULLOH / MAPPING OF SUBAK AREA BOUNDARIES … 212
The boundaries of the subak area are determined based on irrigation canals and natural boundaries,
namely rivers. Subak does not follow administrative boundaries because the subak area existed before
the government set administrative boundaries, such as villages or sub-districts (Aryastana et al., 2020;
Norken et al., 2016; Trigunasih & Saifulloh (c), 2022). Based on Fig. 3, the Tukad Sungsit (river) is
a barrier between the Subak Beji area and Subak Dangin Yeh, which is spatially located on the north
coast of Bali Province.
Fig. 3. Spatial distribution of Subak area as seen from the Bing World Imagery Satellite.
This research focuses on Subak rice fields (wetlands). Spatially, 65 Subaks in Sawan District
are presented in Fig. 4. The northern coastal area contains Subak Labak, Beji, Dangin yeh Guliang,
and Yangai with flat slopes (0-8%). The southern part has steep slopes (25-45% spatially), Subak
Bingin, Bangesawan, and Galungan. The previous mapping of the Subak boundary was carried out
by (Lanya & Manalu, 2021; Lanya et al., 2017; Lanya & Subadiyasa, 2016).
Protection of Subak land is essential to control land conversion into built-up land. The
conversion of Subak land is not only detrimental to farmers. It is also detrimental to the tourism sector
because Subak in Bali is not only for agricultural activities but also for a destination for tourist
attraction (Budiasa et al., 2015; Norken et al., 2016; Sunarta et al., 2019; Sunarta et al., 2021), so
Subak land resources need to be preserved. One of the sustainable Subaks in Bali namely Subak
Jatiluwih.
213
Fig. 4. Spatial distribution of the Subak land.
Subak Jatiluwih, located in Penebel District, Tabanan Regency (8°22'6.68"S, 115° 8'12.64"E), has
become one of the role models in the management of Subak rice fields in Bali (Fig. 5). Apart from
being an agricultural activity, the Subak land is a mainstay tourist destination in Bali, which domestic
and foreign tourists know. The Subak area is located on a steep slope, but water availability for each
rice field is still met. This condition is due to managing irrigation water with one inlet and one outlet
system, which the Subak organization has managed. Even though it is on a steep slope, Subak
Jatiluwih is safe from erosion and landslides. This condition is due to the terracing system on sloping
land. Terraces can minimize runoff due to high rainfall, retain coarse material from upstream areas
and minimize sedimentation.
The traditional Subak land conservation efforts can be duplicated in other areas by considering
each region's local wisdom. This research reviews conservation actions through agricultural land
management based on soil fertility conditions. Effective management is right on target and in the right
location to be effective and efficient. With the findings in this study, practitioners in agriculture carry
out land management (especially in terms of chemistry) with different chemical compositions of
fertilizers. Based on the soil fertility conditions that have been analyzed in each land unit.
Ida Bagus Putu BHAYUNAGIRI and Moh SAIFULLOH / MAPPING OF SUBAK AREA BOUNDARIES … 214
Fig. 5. Map of Subak Jatiluwih rice fields (left) sourced from the Tabanan Regency Agriculture Service,
Natural panorama of Subak Jatiluwih terraces (right), sourced from https://www.klook.com.
4.2. Land Unit Mapping
Land units (LU) are delineated based on the slope and soil type. The soil types in the research
location include brown regosol, gray brown regosol, and yellowish-brown latosol (Fig. 6a). The
slopes at the study site ranged from 0-8%, 8-15%, 15-25%, and 25-45% (Fig. 6b). As well as the
green map, which shows the spatial distribution of Subak land in Sawan District (Fig. 6c). Based on
the overlay, the land unit (Fig. 6d) can be obtained, which is used as a working map in soil sampling
and a basis for determining Subak land management through soil fertility analysis. The land unit is
the basis for the researchers' consideration in analyzing soil fertility data because the soil sample
represents the condition of the soil properties in the field. The soil formation is influenced by parent
material, slope, climate, and others (Jáuregui et al., 2018; Minasny et al., 2008; Phillips, 2017). The
basis for taking soil samples using Land units has also been carried out by previous researchers
(Sardiana et al., 2017; Beisel et al., 2018).
Fig 6. Thematic map of soil types (a), slope (b), Subak area (c),
land units and soil sampling location on field (d).
215
4.3. Mapping of Soil Fertility
The chemical properties of the soil in this study consisted of CEC, base saturation, organic matter,
total P, total K, and pH as supporting data on soil fertility status (Table 2). Table 2.
The results of the analysis of soil chemical properties through the Laboratory and Adjustment to Soil Fertility.
LU
CEC
(me/100 g)
Base
Saturation
(%)
C-
Organic
(%)
P2O5
(mg/100g)
K2O
(mg/100 g)
pH H2O
Soil
Fertility
I
22.62 (M)
99.04 (VH)
4.03 (H)
50.79 (H)
143.31(VH)
6.64 (N)
Moderate
II
27.42 (H)
95.99 (VH)
3.68 (H)
37.01 (M)
202.93 (VH)
6.50 (N)
High
III
26.47 (H)
93.33 (VH)
3.70 (H)
50.99 (H)
142.28 (VH)
6.66 (N)
High
IV
26.38 (H)
96.55 (VH)
3.81 (H)
91.11 (VH)
47.98 (H)
6.55 (N)
High
V
19.32 (M)
93.33 (VH)
3.60 (H)
49.32 (H)
107.38 (VH)
6.30 (BS)
Moderate
VI
27.49 (H)
91.05 (VH)
3.75 (H)
36.91 (M)
118.47 (VH)
6.60 (N)
High
VII
28.77 (H)
93.75 (VH)
6.79 (VH)
21.83 (M)
13.48 (L)
6.58 (N)
Moderate
Data Source: Laboratory Analysis, 2021:(L)Low, (M)Medium, (H)High, (VH)Very High,
(N)Neutral, (BS)Base.
CEC is one of the chemical properties of the soil that is closely related to the availability of
nutrients for plants and is an indicator of soil fertility. The higher the CEC of the soil, the greater the
ability of the soil to absorb and exchange nutrients. Based on the soil analysis results, the soil's CEC
value at the research site, according to the assessment criteria used, is classified as high to moderate
(Fig. 7a). The higher the pH value of the soil, the higher the CEC value of the soil. On the other hand,
hydrolysis does not occur at low pH values, so the soil's CEC value is low (Nadeau & Sullivan, 2015).
Based on the analysis results of the base saturation value in each land units at the research location,
the observed criteria are classified as very high (Fig. 7b). Base saturation is related to releasing these
cations into the soil solution. The higher the cation saturation, the easier it is to release the cation into
the soil solution. In other words, the more readily available the cation is to plants (Utomo et al., 2016).
The high value of base saturation at the research site reflects that there are still many basic cations in
the soil.
Based on the results of the C-Organic analysis of the soil in each land unit in the research location,
it was classified as high to very high criteria (Fig. 7c). Giving organic matter into the soil not only
adds nutrients to plants but also creates conditions suitable for plant growth and can improve water
holding capacity, facilitate root penetration, improve aeration, increase soil pH, CEC, and nutrient
uptake (Meimaroglou & Mouzakis, 2019; Wei et al., 2020). One of the primary sources of soil organic
matter is plant debris that is returned to the soil. Adding organic matter into the soil will liberate the
elements it contains, such as N, P, K, Ca, Mg, and so on, and increase its availability for plants
(Antonkiewicz et al., 2019). Soil organic matter plays a vital role in exchanging cations and, at the
same time, providing nutrients for plants. Soils with high organic matter have a higher CEC than soils
with low organic matter (Wei et al., 2020). Organic matter can increase the adsorption capacity and
cation exchange capacity. This can happen because the weathering of organic matter will produce
humus (organic colloid), a source of negative soil charge, so it has a surface that can hold nutrients
and water.
Based on the P-Total value of the soil in each land unit, it is classified as medium, high to very
high criteria (Fig. 7d). The availability of P in the soil is closely related to soil acidity (soil pH).
According to (Basha, 2020; Sirsat et al., 2017), most soils with a maximum total P-value can be found
at a neutral pH range between 6.0 – 7.0, so the availability of P will decrease if the pH is below 6.0
or above 7.0. According to (Montaño et al., 2021; Papangelou & Mathijs, 2021), the form of
equilibrium is in the form of fixation or dissolution with other nutrients. P in soil is found in various
compounds, most of which are unavailable to plants. Most of the fertilizer applied to the soil cannot
Ida Bagus Putu BHAYUNAGIRI and Moh SAIFULLOH / MAPPING OF SUBAK AREA BOUNDARIES … 216
be utilized by plants because it has reacted with cations, so the efficiency of P fertilization is generally
low to very low.
Based on the results of the K-Total analysis of the soil in each land unit in the research location,
it was included in the criteria of very high, high to low (Fig. 7e). The high value of soil CEC can
affect the soil solution to be able to release potassium and can reduce the potential for leaching of
potassium in the soil (Nakhli et al., 2017). The K-Total value of the soil at the research site, which is
included in the very high, high, and low criteria, is because the CEC value at the research location is
classified as high to moderate. A high soil CEC value can increase the soil's ability to hold K nutrients
so that the soil solution is slow to release K nutrients and reduce leaching potential. The straw, the
rest of the harvest, is also the primary source of K and Si (Silicate). About 80% of plants' nutrient K
is contained in the straw. Therefore, returning crop residues to the soil can slow down the
impoverishment of K and Si nutrients. Returning crop residues to paddy fields has the potential as K
fertilizer, either in fresh form, composted, or burned. According to (Si et al., 2018), in addition to
replacing K fertilizer at a specific dose, straw also plays an essential role in improving the productivity
of paddy fields, increasing fertilization efficiency, and ensuring production stability.
Fig 7. Spatial distribution of the CEC map (a), Base Saturation (b), Soil Organic Mater (c), Phosphor (d),
Potassium (e) and Soil fertility status (f).
217
The limiting factors for soil fertility status (Fig. 7f) found at the research sites were CEC which
was classified as moderate, P-Total, which was classified as moderate, and K-Total, which was
classified as low. Therefore, it is necessary to carry out integrated soil management, such as regularly
returning crop residues to the soil and adding organic matter and fertilizers containing P and K
elements in the form of single fertilizers and compound fertilizers. Adding P and K compound
fertilizers is needed to support optimal land productivity and increase the soil's CEC value. According
(Chenu et al., 2019; Scotti et al., 2015). Types of organic matter can be applied to the soil by returning
crop residues, providing manure, and compost. In addition to maintaining the content of organic
matter in the soil, adding organic matter can also increase P nutrients in the soil.
5. CONCLUSIONS
The area of Subak land in Sawan District is 2,177.33 ha, divided into 65 Subaks. This research is
one of the efforts to manage Subak land to survive sustainably. The conservation through soil fertility
management on Subak land. The limiting factors for fertility status found at the research sites were
CEC which was classified as moderate, P-Total, which was classified as moderate, and K-Total,
which was classified as low. Therefore, it is necessary to carry out integrated soil conservation, such
as regularly returning crop residues to the soil and adding organic matter and fertilizers containing P
and K elements in the form of single fertilizers and compound fertilizers. Adding P and K compound
fertilizers is needed to support optimal land productivity and increase the soil's CEC value. Types of
organic matter can be applied to the soil by returning crop residues, providing manure, and compost.
In addition to maintaining the content of organic matter in the soil, adding organic matter can also
increase P nutrients in the soil.
R E F E R E N C E S
Antonkiewicz, J., Kuc, A., Witkowicz, R., & Tabak, M. (2019). Effect of Municipal Sewage Sludge on Soil
Chemical Properties and Chemical Composition of Spring Wheat. Ecological Chemistry and Engineering S,
26 (3), 583-595.
Arenas-Montaño, V., Fenton, O., Moore, B., & Healy, M. G. (2021). Evaluation of the fertiliser replacement
value of phosphorus-saturated filter media. In Journal of Cleaner Production, 291(125943), 1-18.
Aryastana, P., Yujana, C. A., & Ardantha, I. M. (2020). Irrigation Water Management by Using Remote Sensing
and GIS Technology to Maintain the Sustainability of Tourism Potential in Bali. Journal of Infrastructure &
Facility Asset Management, 2(1), 63-72.
Basha, S. J. (2020). Management of phosphorus and potassium in bidi tobacco (Nicotiana tabacum L.) under
rainfed conditions. Annals Of Plant And Soil Research. 22(4), 420-424.
Bayu, T. (2020). Review on contribution of integrated soil fertility management for climate change mitigation
and agricultural sustainability. Cogent Environmental Science, 6(1), 1823631, 1-21.
Beisel, N. S., Callaham, J. B., Sng, N. J., Taylor, D. J., Paul, A. L., & Ferl, R. J. (2018). Utilization of single-
image normalized difference vegetation index (SI-NDVI) for early plant stress detection. Applications in
Plant Sciences, 6(10), 1-10.
Budiasa, I. W., Setiawan, B. I., Kato, H., Sekino, N., & Kubota, J. (2015). The role of the Subak system and
tourism on land use changes within the Saba watershed, Northern Bali, Indonesia. Journal of the International
Society for Southeast Asian Agricultural Sciences, 21(2), 31-47.
Chenu, C., Angers, D. A., Barré, P., Derrien, D., Arrouays, D., & Balesdent, J. (2019). Increasing organic stocks
in agricultural soils: Knowledge gaps and potential innovations. Soil and Tillage Research, 188.
https://doi.org/10.1016/j.still.2018.04.011
de Lourdes Figueroa Jáuregui, M., Menez, M. R. M., Solorio, C. A. O., & Reynoso, D. F. (2018). Influence of
factors of soil formation in the properties of soils in Mixteca, Oaxaca, México. Terra Latinoamericana, 36(3),
287-299.
Ida Bagus Putu BHAYUNAGIRI and Moh SAIFULLOH / MAPPING OF SUBAK AREA BOUNDARIES … 218
Diara, I. W., Suyarto, R., & Saifulloh, M. (2022). Spatial Distribution Of Landslide Susceptibility In New Road
Construction Mengwitani-Singaraja, Bali-Indonesia: Based On Geospatial Data. Geomate Journal, 23(96),
95-103.
Norken IN, Suputra IK, & Arsana IGNK. (2016). Challenges to the Conservation of Subak System as World
Cultural Heritage in Bali. Journal of Agricultural Science and Technology B, 6(4), 1-9.
Kome, G. K., Enang, R. K., Tabi, F. O., & Yerima, B. P. K. (2019). Influence of Clay Minerals on Some Soil
Fertility Attributes: A Review. Open Journal of Soil Science, 09(09), 155-188.
Lanya, I., & Manalu, T. J. (2021). Remote sensing and GIS application for mapping data base of sustainable
agriculture land in Denpasar City. IOP Conference Series: Earth and Environmental Science, 648(1), 1-11.
Lanya, Indayati, & Netera Subadiyasa, N. (2016). Role of Remote Sensing and Geographyc Information System
Mapping for Protected Areas Land Rice Field Subak, Buffer Zones, and Area Conversion (Case Studies in
Gianyar Regency, Bali Province). IOP Conference Series: Earth and Environmental Science, 47(1). 1-11.
Lanya, Indayati, Subadiyasa, N. N., & Hutauruk, J. (2017). Subak Land Information System Based On Remote
Sensing And Geographic Information System In Denpasar City. Geoplanning: Journal of Geomatics and
Planning, 4(2). 1-12.
Liu, C., Qin, Y. S., & Zhao, X. L. (2020). Long-term effect of fertilization on accumulation and availability of
heavy metal in a calcareous paddy soil. Journal of Agro-Environment Science, 39(7), 1494-1502.
Meimaroglou, N., & Mouzakis, C. (2019). Cation Exchange Capacity (CEC), texture, consistency and organic
matter in soil assessment for earth construction: The case of earth mortars. Construction and Building
Materials, 221, 27-39.
Minasny, B., McBratney, A. B., & Salvador-Blanes, S. (2008). Quantitative models for pedogenesis - A review.
In Geoderma, 144, 140–157.
Nadeau, M. B., & Sullivan, T. P. (2015). Relationships between Plant Biodiversity and Soil Fertility in a Mature
Tropical Forest, Costa Rica. International Journal of Forestry Research, 2015, 1–13.
Nakhli, S. A. A., Delkash, M., Bakhshayesh, B. E., & Kazemian, H. (2017). Application of Zeolites for
Sustainable Agriculture: a Review on Water and Nutrient Retention. Water, Air, and Soil Pollution, 228(12),
1-34.
Nicoleta, M., Mihail, D., Carmen, S., & Traian, C. (2018). The influence of n and p fertilization on some chemical
characteristics of the soil. International Multidisciplinary Scientific Geo Conference Surveying Geology and
Mining Ecology Management, SGEM, 18(3.2), 575-582.
Olsen, S. R. (1954). Estimation of available phosphorus in soils by extraction with sodium bicarbonate (No. 939).
US Department of Agriculture.
Papangelou, A., & Mathijs, E. (2021). Assessing agro-food system circularity using nutrient flows and budgets.
Journal of Environmental Management, 288, 1-22.
Phillips, J. D. 2017. Soil Complexity and Pedogenesis. In Soil Science. 182 (4), 117-127.
Prabakaran, G., Vaithiyanathan, D., & Ganesan, M. (2021). Soil fertility review using fuzzy logic. In Journal of
Engineering Research (Kuwait), 9, 192-202.
PPT (1995). Guidelines for analysing soil chemical properties in Indonesia. Soil Research Center Department,
Bogor-Indonesia. http://balittanah.litbang.pertanian.go.id/ind/
Sardiana, I. K., Susila, D., Supadma, A. A., & Saifulloh, M. (2017). Soil Fertility Evaluation and Land
Management of Dryland Farming at Tegallalang Sub-District, Gianyar Regency, Bali, Indonesia. IOP
Conference Series: Earth and Environmental Science, 98(1), 1-11.
Scotti, R., Bonanomi, G., Scelza, R., Zoina, A., & Rao, M. A. (2015). Organic amendments as sustainable tool
to recovery fertility in intensive agricultural systems. In Journal of Soil Science and Plant Nutrition. 15(2).
333-352.
Si, L., Xie, Y., Ma, Q., & Wu, L. (2018). The short-term effects of rice straw biochar, nitrogen and phosphorus
fertilizer on rice yield and soil properties in a cold waterlogged paddy field. Sustainability (Switzerland),
10(2), 1-17.
Siregar, E. G., Adi, I. G. P. R., & Supadma, A. . N. (2021). Mapping the Fertility Status of Rice Fields Based on
Geographic Information Systems in Subak Buaji and Subak Padanggalak, East Denpasar District. Jurnal
Agroteknologi Tropika, 10(1). 1-10.
Sirsat, M. S., Cernadas, E., Fernández-Delgado, M., & Khan, R. (2017). Classification of agricultural soil
parameters in India. Computers and Electronics in Agriculture, 135, 269-279.
Suasih, N. N. R., Darma, I. K., & Sara, I. M. (2018). The Role of Subak (Traditional Farmers Institution In Bali)
To Farmers Welfare After The Cultural Landscape of Subak Inscribed As A World Heritage. Russian Journal
of Agricultural and Socio-Economic Sciences, 75(3), 36-47.
Subedi, T. 2018. Analysis of plant nutrient elements of soil in Pokhara. Himalayan Biodiversity, 6, 58-62.
219
Sumiyati , Windia, I. W., & Tika, I. W. (2017). Operation and maintenance of subak irrigation network in
Tabanan Regency. Jurnal Kajian Bali (Journal of Bali Studies), 7(1).
Sunarta, I. N., Adikampana, I. M., & Nugroho, S. 2019. The Existence of Subak inside the Northern Kuta
Tourism Area, Bali. IOP Conference Series: Earth and Environmental Science, 313(1), 1-8.
Sunarta, I. Nyoman, Nugroho, S., & Adikampana, I. M. (2021). Spatial Transformation of Subak in Northern
Kuta Tourism Area, Bali: From Agricultural to Cultural-Service. South Asian Journal of Social Studies and
Economics, 9(1), 26-38.
Sunarta, I. N., & Saifulloh, M. (2022). Coastal Tourism: Impact For Built-Up Area Growth And Correlation To
Vegetation And Water Indices Derived From Sentinel-2 Remote Sensing Imagery. GeoJournal of Tourism
and Geosites, 41(2), 509-516.
Trigunasih, N.M., & Saifulloh. M. (a). (2022). Spatial Distribution of Landslide Potential and Soil Fertility: A
Case Study in Baturiti District, Tabanan, Bali, Indonesia. Journal of Hunan University Natural Sciences,
49(2).
Trigunasih, N. M., & Saifulloh, M. (b). (2022). The Investigating Water Infiltration Conditions Caused by
Annual Urban Flooding Using Integrated Remote Sensing and Geographic Information Systems. Journal of
Environmental Management and Tourism, 13(5), 1467-1480.
Trigunasih, N. M., & Saifulloh, M. (c). (2022). Correlation between soil nitrogen content and NDVI derived
from sentinel-2A satellite imagery. Jurnal Lahan Suboptimal: Journal of Suboptimal Lands, 11(2), 112-119.
Walkley, A., & Black, I. A. (1934). An examination of the Degtjareff method for determining soil organic matter,
and a proposed modification of the chromic acid titration method. Soil science, 37(1), 29-38.
Wei, H., Liu, Y., Xiang, H., Zhang, J., Li, S., & Yang, J. (2020). Soil ph responses to simulated acid rain leaching
in three agricultural soils. Sustainability (Switzerland), 12(1), -12.
Windia, I. W., & Wiguna, W. A. A. (2013). Subak world cultural heritage. Udayana University Press.
Windia, W., Suamba, I. K., Sumiyati, S., & Tika, W. (2018). Subak System for Environmental Development
Based on Tri Hita Karana. SOCA: Jurnal Sosial Ekonomi Pertanian. 118-132.
