Indonesia has a land area of 191.09 million ha, consisting of 511 regencies/cities (BPS 2013), has a variety of land resource characteristics due to the diversity of climate, topography, par- ent material/lithology, and other environmen- tal bio-physical conditions. Therefore, for the development of agricultural commodities, an instrument that can be scientifically justified is needed. One of the instruments used is the land suitability approach, which is an assessment that provides information on potential and or land use as well as production expectations that may be obtained as well as environmentally friendly land uses (Sukarman et al. 2018). Land suitability is the suitability of a plot of land for a particular use (Ritung et al. 2011). Specifically, land suitability is the suitability of the physical characteristics of the environment, namely cli- mate, soil, topography, hydrology and or drain- age for farming or certain commodities that are productive, environmentally friendly and take into account the impacts of climate change.
Some of the new agricultural lands in Indonesia have applied the results of their land suitability assessment, but there are still many lands that have been used for a long time that have not used the principle of land suitability, especially
in mountainous areas with steep slopes.
Land suitability evaluation in Indonesia is currently evolving from land evaluation based on the framework of FAO (1976). Furthermore, this method was developed by the Center for Soil Research / Indonesian Center for of Agri- cultural Land Resources Research and Develop- ment adapted to the characteristics of the land and the growing requirements of various com- modities in Indonesia to select the types of com- modities that can be developed in an area. The commodity groups in question include wet land food crops (paddy rice), dry land food crops, lowland horticultural crops, highland horticul- tural crops, lowland plantation crops, highland plantation crops, and forestry plants. In the last land suitability assessment mentioned above, the inhibiting factors due to climate change have been considered. Thus, in the recommen- dations for land use, efforts to adapt to climate change can be made.
The land evaluation system that has devel- oped so far uses various approaches, including the parameter multiplication system, addition and matching system or matching between land quality/characteristics with plant growth requirements (Ritung et al. 2011). Several land evaluation systems that have been used and No. 61 of 2011, concerning the National Action Plan for Reducing Greenhouse Gas Emissions is one of the efforts to overcome this problem. This effort has been followed up by compiling a technical guidebook that describes the scientific basis for calculating greenhouse gas emissions in the business as usual (BAU) scenario and several emission reduction scenarios.
One of the consequences of land cover changes can cause green house gas emissions.
The emission factor for land cover change is the difference in the amount of carbon stock when land with one cover class changes to another cover. To obtain these emission factors, it is necessary to have reference data (default) for carbon stocks from all types of land cover. For each type of land cover, a representative reference figure is built from the results of research or national inventories in various locations which are then averaged. Depending on the availability of data, for land cover at the national level the reference carbon stock data comes from various locations representing dry and wet climates and from fertile and infertile lands. Accordingly, if data is available for the provincial level, representative data is used from various locations within the province (Agus et al. 2013).
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Figure 9.1. Examples of land use change from forest to agricultural land
have been developed in Indonesia include:
According to Ritung and Sukarman (2014) in land suitability assessment there are three main factors that must be considered, namely: crop requirements, management requirements and conservation requirements. The three main fac- tors are reflected in the quality and characteris- tics of the land.
Data source
Semi detailed soil map
In determining the suitability of land for ag- ricultural commodities, it is necessary to have basic data containing data on land/soil charac- teristics. The basic data are in the form of digital data and tabular data of land/soil resources re- sulting from land mapping. The most recent and Figure 9.2. Agricultural land that applies soil and water conservation principles and agricultural land that does not apply soil and water conservation principles
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Figure 9.3. Soil observation in wet and dry land
large-scale data is the result of semi-detailed soil mapping (scale 1: 50,000). The semi-detailed soil maps are presented in the form of Atlas of Semi-Detailed Soil Maps at a scale of 1:50,000 per district/city throughout Indonesia (Figure 9.3) and in the form of a data base (big data).
Currently the Map Atlas is available in 511 dis- tricts/cities throughout Indonesia. This map was created and correlated from 2016 to 2019, based on the existing data base at BBSDLP and addi- tional observations were made.
This land resource data is used to assess land suitability classes and sub-classes as well as rec- ommendations for their use. Thus, the character- istics of the soil and its environment are used as the basis for determining the recommendations for land use, so that when there is a change in land use, it will not cause environmental dam- age, nor the possibility of carbon emissions due to changes in land use.
Peatland map of Indonesia
Peatlands are part of swamp land, name- ly land that occupies a transitional position between land and water systems. This land
throughout the year or for long periods of the year is always waterlogged or inundated (BBSDLP 2019). According to Government Regu- lation No. 27 of 1991, swamp land is land that is naturally inundated with water that occurs con- tinuously or seasonally due to obstructed natu- ral drainage and has special physical, chemical and biological characteristics. Swamp land is di- vided into: (a) tidal swamp/coastal swamp, and (b) non-tidal swamp/inland swamp (Minister of Public Works Decree No. 64/PRT/1993).
Based on the Soil Taxonomy system (USDA, 2014), peat soils are called Histosols (histos = tissue), while in the National Soil Classification system (Dudal and Soepraptohardjo 1961) peat soils are called Organosols (soil composed of or- ganic matter). In the National Soil Classification (Subardja et al. 2016), peat soil or Organosol is soil that has an H horizon > 50 cm thick (if the organic matter consists of spaghnum or moss >
60 cm or has a bulk density of < 0.1 gr cm-3 ) from the soil surface, or cumulatively 50 cm within 80 cm of the top layer; The thickness of the H hori- zon may decrease if there are rock layers or rock fragments filled with organic matter in between.
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The Indonesian Center for of Agricultural Land Resources Research and Development (ICALRRD) as the guardian of peatland maps has carried out mapping of peatlands at a scale of 1:50,000 based on districts/cities since 2013.
Until 2019, mapping of peatlands at a scale of 1:50,000 has been carried out in 130 districts / cities identified as having peat, covering the is- lands of Sumatra, Kalimantan, Sulawesi and Pap- ua.
The peatland map that has been produced has been used as a reference in determining the use of the land, so that any change in peatland cover must pay attention to the characteristics of the land. It is hoped that by referring to the characteristics of the peat, if there is a change in land use it will not cause environmental prob- lems, especially the emission of greenhouse gas- es from peat.
Peatlands in Indonesia are used as forests, shrubs, plantations (oil palm, coconut, rubber), and food agriculture. Shrubs on peatlands are
unproductive land, in addition to increasing greenhouse gas emissions, it will also increase the risk of land fires, reduce biodiversity and re- duce watershed stability. The economic and so- cial benefits of bushland are very low, even neg- ative because of the high threat of fire hazard.
Based on the results of spatial calculations from updating the peat map using data from the latest research results, the total area of peat land on a 1:50,000 scale map in 4 main islands, namely Sumatra, Kalimantan, Sulawesi and Pap- ua is 13,430,517 ha, consisting of Sumatra Island covering an area of 5,850,561 ha, Kalimantan with an area of 4,543,362 ha, Sulawesi with an area of 24,783 ha and Papua covering an area of 3,011,811 ha (Table 1). The results of this peat mapping have been published in the Q1 glob- al indexed International Journal, Geoderma in 2021 (Anda et al. 2021).
Figure 9.4. Peatland Map of Indonesia Scale 1: 50.000
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Land suitability map
The 1:50,000 scale land suitability map is gen- erated from the 1:50,000 scale soil map through land evaluation activities. Land evaluation is done by matching (matching) between land quality/characteristics (Land quality/character- istics) with land use requirements. The result of this activity is information on the level of land suitability for a particular use as indicated by the land suitability class and limiting factors, as well as its area and distribution in an area. Further- more, based on the limiting factors found, rec- ommendations for land management are drawn up to increase the productivity of strategic agri- cultural commodities.
With the results of this land suitability assess- ment, it is hoped that every new land clearing for agricultural commodities follows the recom- mendations for land use based on the results of the land suitability assessment. By following these recommendations, it is hoped that chang- es in land use will not result in excessive carbon emissions. Even for lands that were originally in the form of shrubs which were converted into agricultural land (annual plants) which have high CO2 absorption capabilities, so as to reduce carbon emissions from the land.
The 1:50,000 scale land suitability map con- tains information with a fairly high accuracy, so it can be used to support agricultural devel- opment planning at the district/city level. Until 2019, an Atlas of land suitability maps and di- rections for agricultural commodities was pro- duced, as well as recommendations for land management in 511 regencies/cities through- out Indonesia. An example of an Atlas of Land Suitability Maps and Commodity Directions in two districts of DI Yogyakarta Province is pre- sented in Figure 9.6.
Land suitability maps at a scale of 1: 50,000 should be used as a guide when taking land use changes, for example when opening new agri- cultural land. With the guidelines, the impact of changes in land use will have very little effect on environmental changes related to the possibility of greenhouse gas emissions. Based on the re- ality in the field, it is not always in accordance with the recommendations for land use, so it is very possible that any change in this use will af- fect changes in plant biomass that cause green- house gas emissions.
Figure 9.5. Profile of peat soil and oil palm plantations on peat soils Land Use Change